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Queensland Dengue Management Plan (DMP)

2 Queensland Dengue Management Plan 2010 > 2015

Title

This plan shall be titled and known as the:Queensland Dengue Management Plan

Authorisation

The queensland Dengue Management Plan is issued under the authority of the Chief Health Officer and is a sub-plan to the queensland Joint Strategic Framework for Mosquito Management.

To meet the challenge of preventing or minimising dengue outbreaks in Queensland, Queensland Health in collaboration with local government and other key stakeholders have developed the Queensland Dengue Management Plan 2010-2015 (DMP). This plan serves to guide and coordinate efforts to manage dengue in Queensland.

APPROVED BY:

Sophie DwyerExecutive Director, Health Protection

Date: 11 February 2011

Disclaimer

This plan is intended for information purposes only. The information contained within this plan is based upon best available evidence at the time of completion. Queensland Health does not accept liability to any person for the information or advice provided in this document, or incorporated into it by reference or for loss or damages incurred as a result of reliance upon the material herein.

Authority and Planning Responsibility

The development, implementation and revision of this Plan are the responsibility of the Senior Director, Communicable Diseases Branch.

Proposed amendments to this plan are to be forwarded to:

DirectorCommunicable Disease Prevention and Control UnitCommunicable Diseases BranchQueensland Health15 Butterfield StHerston Qld 4006Po Box 2368 Fortitude Valley BC 4006

This plan will be updated and available electronically on the Queensland Health Website.

Acknowledgements

The DMP was developed in consultation with the following agencies:

2 Queensland Health

2 Local Government Association of Queensland

2 International Vector Consultants

2 Brisbane City Council

2 Gold Coast City Council

2 Sunshine Coast Regional Council.

The DMP is based on the Dengue Fever Management Plan for north Queensland 2005-2010 developed by the Tropical Public Health Unit, Queensland Health and recognised as an international best practice model. This DMP would not be possible without the contribution from those stakeholders involved in the development and subsequent reviews of the Dengue Fever Management Plan for north Queensland 2005-2010.

1

Abbreviations and Glossary 2

Executive Summary 4

Introduction 5

1.1 Aim 51.2 Purpose 51.3 Objectives 51.4 Scope 51.5 Legislation 6

Background 7

2.1 What is dengue? 72.2 Geography of dengue in Australia 82.3 History of imported cases in Queensland 92.4 History of dengue outbreaks in Queensland 102.5 Dengue mosquito vector 102.6 How does dengue spread 11

Dengue outbreak risk 12

3.1 Dengue activity levels and responses 123.2 Stakeholders and their roles 14

Mosquito surveillance and control 15

4.1 Dengue mosquito surveillance 154.2 Dengue mosquito control 18

Disease surveillance 22

5.1 Routine disease surveillance 225.2 Disease surveillance and response for sporadic cases 235.3 Surveillance for outbreak response 25

Managing large or multiple dengue outbreaks 27

6.1 HPPIMS activation 276.2 Relationships with other agencies and the public 276.3 Concept of operations 28

Public Awareness and Community Engagement 30

7.1 Routine public awareness and community engagement 307.2 Public awareness in response to sporadic cases 317.3 Public awareness in response to an outbreak 317.4 Health promotion research and evaluation 327.5 Professional education and staff training 32

References 33

Appendices 34

Appendix 1: Specific dengue tests 34Appendix 2: Example of test results and incorrect diagnoses of dengue 36Appendix 3: Dengue case report form 37Appendix 4: Timeline of dengue 2 outbreaks, Cairns 2003-2004 39Appendix 5: Dengue Mosquito Surveillance Methods 40Appendix 6: Ovitraps 42Appendix 7: How to calculate Ae. aegypti indices and risk assessment in the non-dengue zone 45Appendix 8: Container breeding mosquito survey form 46Appendix 9: How to calculate breeding site prevalence in the non-dengue zone 47

Contents


Aedes aegypti - The main mosquito vector for dengue in Queensland

Aedes albopictus - Exotic dengue vector, detected and established throughout the Torres Strait (Qld) since 2005

Antigen - A substance which can induce a specific immune response and react with the products of that response

AQIS - Australian Quarantine and Inspection Service

Assay - A laboratory test that not only is able to detect something (eg. An antibody) but also is able to measure the amount (eg. of the antibody) present

Authorised Person/Officer - A person appointed as an authorised person under section 377 of the Public Health Act 2005

BGS traps - BioGents Sentinel adult mosquito traps

CDB - Communicable Diseases Branch

CDC - Communicable Disease Control

CEO - Chief Executive Officer

DART - Dengue Action Response Team

DEHS - Director of Environmental Health Services

Dengue - Infection caused by one of four serotypes of dengue viruses transmitted by Aedes aegypti and Aedes albopictus

DHF - Dengue Haemorrhagic Fever - Potentially fatal complication of dengue, characterised by severe bleeding

DMP - Dengue Management Plan

DSS - Dengue Shock Syndrome - Potentially fatal complication of dengue, characterised by shock

Dengue Warning Area - Suburb or town that has had confirmed local transmission of dengue during an outbreak, delineated by specific geographical boundaries

Dengue Watch Area - Suburbs, towns or cities that are at risk of local transmission of dengue during an outbreak

EHO - Environmental Health Officer

EHW - Environmental Health Worker

EIA - Enzyme immunoassay: used to test biological samples (eg. blood) for the presence of antibodies

Endemic - The constant presence of a disease or infectious agent within a given geographic area or population group

Epidemic - The occurrence in a community or region of cases of an illness or other health-related events clearly in excess of what is expected

GIS - Geographic Information System - Computerised information system used to analyse, manage and present data linked to location

GP - General Practitioner

Abbreviations and Glossary

3

GPQ - General Practice Queensland

HIC - Health Incident Controller

HPPIMS - Health Protection Program Incident Management System

IEC - Information Education and Communication materials

IgM and IgG - Two different classes of antibodies: In the case of dengue fever, IgM indicates a recent or acute infection whereas IgG indicates a prior infection

Imported case- A confirmed dengue case with recent travel history from a known dengue endemic region

IMT - Incident Management Team

Inter-epidemic - Periods between epidemics

JE - Japanese encephalitis: Infection caused by a virus transmitted by mosquitoes

ME - Medical Entomologist

NOCS - Notifiable Conditions System

Outbreak - A localised, as opposed to generalised epidemic (NB: One case of locally-acquired dengue in Queensland is enough to declare an outbreak)

PCI - Premise Condition Index

PCR - Polymerase chain reaction (a technique used to amplify specific sequences of genetic material so that they may be more easily identified. May be applied to the detection of dengue virus)

PHMO - Public Health Medical Officer

PHN - Public Health Nurse

PHU - Public Health Unit

QHFSS - Queensland Health Forensic and Scientific Services

Routine - Non-outbreak situations

Serotype - A strain of a micro-organism that has been distinguished from other strains by a serological (i.e. immunological) test

VCO - Vector Control Officer

Vector - A living carrier that transports an infectious agent from an infected individual to a susceptible individual

Viral culture - The isolation of a virus by propagating it in a special culture medium

Viraemia - The presence of viruses in the blood

WHO - World Health Organization


The nature of dengue fever in Queensland is changing as it is throughout the tropical and subtropical world. The World Health Organization (WHO) estimates that approximately 50 million dengue infections occur worldwide every year. Of this figure an estimated 500,000 people contract dengue haemorrhagic fever (DHF), a potentially life threatening complication of dengue. Dengue is now endemic in more than 100 countries in Africa, the Americas, the Eastern Mediterranean, South-East Asia and the Western Pacific.

The transmission of dengue is associated with an expanding geographic distribution of the four dengue viruses and their mosquito vectors. The main vector of dengue, Aedes aegypti (Ae. aegypti) is widespread throughout urban tropical north Queensland and has been detected in many towns in sub-tropical Queensland as far south as Goomeri near the coast and Charleville in the west. Aedes aegypti is predominantly a domestic, day biting mosquito that feeds mainly on humans. Since 2005 an exotic vector of dengue, Aedes albopictus (Ae. albopictus) has become established on the majority of islands in the Torres Strait and threatens to invade the mainland. The risk of dengue transmission in central and southern Queensland and other jurisdictions would be substantially increased if this vector became established on the mainland. Recent changes in domestic water storage practices along with significant numbers of imported cases of dengue among international travellers in Queensland contribute to the increased risk of dengue outbreaks.

Outbreaks of dengue in Queensland have increased in frequency and intensity since the early 1990s. In 2003 and 2004, there were six outbreaks of dengue in north Queensland with a combined total of nearly 900 cases reported in Cairns, Townsville and the Torres Strait. Two Torres Strait Island residents were hospitalised with severe and life-threatening symptoms of dengue haemorrhagic fever (DHF). There were also the first two recorded fatalities in Australia in many decades. Again in 2008 and 2009 over 1000 cases were reported in north Queensland, the worst dengue outbreak in Queensland for 50 years. This highlights the public health risk posed to Queensland communities.

To meet the challenge of preventing or minimising dengue outbreaks throughout Queensland, Queensland Health in collaboration with local government and other key stakeholders have developed the Queensland Dengue Management Plan 2010-2015 (DMP).

The DMP focuses on three key areas integral to dengue management that are recognised as international best practice, i.e. ongoing prevention, sporadic case response and outbreak management which can all be used independently or consecutively to effectively manage dengue in Queensland.

This document also includes a number of relevant resources and references that complete a comprehensive and holistic guide to dengue management in Queensland.

Executive Summary

5Chapter 1 Introduction

1.1 Aim

The aim of this plan is to minimise the number of locally acquired cases of dengue in Queensland by strengthening and sustaining risk based surveillance, prevention and control measures for both human cases and the mosquitoes that carry the dengue virus.

The DMP aims to achieve this by improving disease surveillance, enhancing and coordinating mosquito surveillance, prevention and control measures and by educating the community, industry and relevant professional groups.

1.2 Purpose

The purpose of the DMP is to provide clear guidance on best practice in disease and mosquito surveillance, prevention and control methods for dengue management in Queensland.

1.3 Objectives

The DMP has four objectives:

2 ensuring the timely detection and reporting of all suspected dengue cases

2 supporting effective and timely control methodologies to prevent local transmission of dengue

2 establishing a state-wide surveillance program for the detection of dengue vectors in Queensland

2 reducing the spread of the dengue vectors across Queensland.

1.4 Scope

The DMP outlines three central components of dengue management:

2 mosquito surveillance and control

2 disease surveillance

2 public awareness and community engagement.

The DMP outlines the existing procedures for dengue management in Queensland for each of the three component areas.

The DMP calls for continued and improved collaboration in dengue management between Queensland Health, other government agencies and non-government stakeholders so ensuring relevance to all interested parties.

The DMP does not include advice on the clinical management of people with dengue.

For up to date information on dengue in Queensland, visit Queensland Health’s dengue website: www.health.qld.gov.au/dengue

CHAPTER1

Introduction


1.5 Legislation

The primary pieces of legislation used in disease surveillance and mosquito management in Queensland are:

2 Public Health Act 2005

2 Public Health Regulation 2005

2 Pest Management Act 2001

2 Pest Management Regulation 2003.

There are two avenues available for controlling local government public health risks as defined in Chapter 2 Part 1 of the Public Health Act 2005. These are either an Approved Inspection Program or an Authorised Prevention and Control Program.

The Chief Executive of Queensland Health or the Chief Executive Officer of a local government can approve an Approved Inspection Program under which authorised persons may enter places to monitor compliance with a regulation referring to public health risks. A Prevention and Control Program can be approved by the Chief Executive of Queensland Health if there is, or is likely to be, an outbreak of a disease capable of transmission to humans by a designated pest, or a plague or infestation of a designated pest including mosquitoes.

The provisions for Approved Inspection Programs are contained in Chapter 9 Part 4 of the Public Health Act 2005 and those pertaining to Authorised Prevention and Control Programs are contained in Chapter 2 Part 4 of the Act.

Under the Public Health Regulation 2005 local governments can also require residents to control mosquito breeding on their properties and maintain compliance of water tanks.

For further details of these programs and requirements, including information on powers of entry, please refer to Public Health Act 2005 Resource Kit:

http://www.health.qld.gov.au/eholocalgov/secure_area/publichealthact2005/resource_kit.asp

Reporting responsibilities of Medical Officers, persons in charge of hospitals and Directors of pathology laboratories in relation to notifiable diseases, including dengue fever, are outlined in Chapter 3 Part 2: Notifiable Condition Register of the Public Health Act 2005. The Act states that a Medical Officer must report a notifiable condition if the person has a clinical or provisional diagnosis. Please refer to: http://www.legislation.qld.gov.au for detailed information and amendments on the Public Health Act 2005 and the Pest Management Act 2001.

7Chapter 2 Background

2.1 What is dengue?

Dengue is an infection caused by one of four dengue viruses in the family Flaviviridae. Other diseases caused by flaviviruses include yellow fever, Japanese encephalitis and Murray Valley encephalitis. In terms of morbidity, mortality and economic costs, dengue is the most important mosquito-borne viral disease of humans.

Dengue occurs in over 100 countries worldwide and is found primarily in urban settings in the tropics (see Figure 1). Fifty million cases of dengue are reported around the world each year and over 2.5 billion people are at risk of infection.

CHAPTER2

Background

There are four dengue virus serotypes (DENV- 1, 2, 3 and 4) and genetic variants of these serotypes are found in different geographic locations. Therefore a person can acquire a maximum of four dengue infections during their lifetime, one infection with each dengue serotype. Infection with one dengue serotype confers immunity to that particular serotype, but may result in an increase risk of complications if subsequent infections with other serotypes occur. Infection with the dengue virus may be subclinical (asymptomatic) or may cause illness ranging from a mild fever to a severe, even fatal, condition such as dengue haemorrhagic fever (DHF) or dengue shock syndrome (DSS). Hospitalisation may be required depending on the severity of symptoms. DHF manifests generally as plasma leakage leading to shock that can be fatal, particularly among young children.

Figure 1: Countries/areas at risk of dengue transmission, 2007 (WHO 2007)


Approximately 2.5% of people affected with DHF die, although with experience in dealing with DHF and timely treatment this rate is often reduced to less than 1 per cent. There is no vaccine to provide immunity from dengue.

Typical dengue symptoms include:

2 sudden onset of fever (lasting three to seven days) and extreme fatigue

2 intense headache (especially behind the eyes)

2 muscle, joint and back pain

2 loss of appetite, vomiting and diarrhoea

2 skin rash

2 minor bleeding (nose or gums).

The incidence of dengue worldwide is increasing. Papua New Guinea (PNG), for example, has been a significant source of dengue with frequent incursions into the Torres Strait Islands. The main reasons for escalating incidents of dengue can be attributed to increasing urbanisation, air travel and the increasing use and disposal of consumable and commercial goods, such as discarded car tyres, that facilitate mosquito breeding.

2.2 Geography of dengue in Australia

Dengue has historically been reported in most states and territories, but locally acquired dengue has only been reported in north Queensland in recent decades.

Transmission of the virus is limited by the distribution of its vector, the mosquito Ae. aegypti in Queensland (see Figure 2). While dengue is not endemic in Queensland, Ae. aegypti is widespread throughout urban tropical north Queensland and has been detected in many towns in sub-tropical Queensland as far south as Goomeri near the coast and Charleville inland.

The geography of dengue in Australia could change dramatically following the establishment of Ae. albopictus on the majority of islands in the Torres Strait since 2005. Although not as capable a vector as Ae. aegypti, this species was the sole vector for a dengue outbreak in Hawaii in 2001. Its role in dengue outbreaks on mainland Australia will remain to be seen. Simulation models indicate that it has capacity to spread through most of coastal Australia due to its greater tolerance to cold climates.

Figure 2: Distribution of Aedes aegypti and dengue activity in Queensland


2.3 History of imported cases in Queensland

A single imported viraemic person unwell with dengue in an area populated by a dengue vector and human hosts can lead to a dengue outbreak in Queensland. Dengue is not endemic to Australia and local dengue outbreaks, currently confined to north Queensland, all begin with a single imported case referred to as ‘patient zero’.

Queensland Health currently relies on surveillance by medical practitioners and diagnostic laboratories to detect imported cases. Since 1999 Queensland Health has been notified of an increasing number of imported cases per year. Currently most imported cases originate in Indonesia, Thailand, the Philippines and Papua New Guinea (PNG).

There is a high level of dengue activity in PNG at any given time. For example, all four serotypes of dengue were active in PNG in early 2004. The Torres Strait islands are geographically very close to PNG and the islands receive many visitors from PNG. This increases the risk of importations of dengue to the Torres Strait islands, making it one of the priority ‘hot spots’ for dengue surveillance and control.

Figure 3 shows the outbreak pattern that occurred in the Torres Strait in 1996 - 1997. The outbreak started with one person who returned to Mer in the Torres Strait after contracting dengue in Daru in PNG. Due to the significant numbers of Ae. aegypti on Mer Island, this one case led to a further 70 cases on the island. Subsequent travel of viraemic patients between islands resulted in infections on at least six other islands in the Torres Strait. Within seven months, 201 cases were confirmed, reaching locations as far south as Townsville. Similarly in 2008-9 a major epidemic originated in Cairns with cases distributed to Townsville, Mareeba and the northern peninsula area.

Figure 3: Map of dengue transmission in Torres Strait: 1996 ~ 97*


2.4 History of dengue outbreaks in Queensland

Queensland has a history of dengue epidemics dating back to 1879, most of which occurred in north Queensland. Thirteen notable dengue epidemics have occurred in Queensland since 1885. The first fatality attributed to dengue occurred in Charters Towers in 1885 and the first fatality attributed to DHF occurred in the same town during the 1897 epidemic, when 60 fatalities were recorded (30 of those were children). Table 1 shows the number of dengue notifications by place of acquisition for Queensland in the past 10 years.

Table 1: Dengue notifications by place of acquisition for Queensland (2000 - 2009)

Year Queensland acquired Overseas acquired Not stated Total

2000 50 25 10 85

2001 8 22 12 42

2002 25 50 6 81

2003 667 51 7 725

2004 228 33 11 272

2005 75 26 8 109

2006 36 31 8 75

2007 46 40 31 117

2008 22 56 12 90

2009 912 83 38 1033

Grand Total 2069 417 143 2629

2.5 Dengue mosquito vector

In Queensland, the dengue virus is almost exclusively transmitted by the highly domesticated Ae. aegypti mosquito. Aedes aegypti is unusual in that it breeds primarily in domestic environments and does not often bite at night. An exotic species, Ae. albopictus (a less competent vector of dengue), is also a concern for colonising mainland Queensland and Australia due to its detection (May 2005) and rapid establishment in the Torres Strait, despite the efforts of a mosquito control program by Queensland Health and the Commonwealth Government to contain the species. This vector was detected on the northernmost tip of Cape York in 2009. Intense eradication measures by Queensland Health and local government successfully prevented the establishment of Ae. albopictus in this location.

2.5.1 Breeding and larval habitat

Aedes aegypti breed primarily in artificial containers holding water, including cans, buckets, jars, pot plant dishes, birdbaths, boats, tyres and tarpaulins. With the recent emphasis placed on domestic water storage in Queensland, poorly maintained roof gutters and rainwater tanks continue to be important potential breeding sites.

These mosquitoes can also breed in natural sites such as bromeliads and fallen palm fronds. Subterranean sites such as wells, telecommunication pits and drain sumps can also be important breeding sites, especially in drier conditions.

In addition to artificial breeding sites Ae. albopictus also breeds in other natural environments such as tree holes.


2.5.2 Adult mosquito behaviour

Unlike most mosquitoes that prefer swamps and bushland, Ae. aegypti is truly domesticated and prefers to live in and around people’s homes. The adult Ae. aegypti mosquito likes to rest in dark places such as wardrobes and under beds. Females are very cautious when biting, being easily disturbed and prefer to bite humans during daylight hours. Household residents can exert a much higher degree of control on exposure to this species because it does not disperse far from breeding sites (e.g. 100-200 m). Aedes albopictus on the other hand is more dispersive and tolerant of cooler climates.

2.6 How does dengue spread

A female dengue mosquito becomes infected with dengue when it bites a human who is viraemic with the dengue virus (i.e. there is enough dengue virus in the person’s blood to infect a mosquito). Generally in 8 -12 days the infected mosquito is able in turn to transmit the virus to people. One dengue-infected female mosquito is capable of biting and infecting several people during one feeding session. Consequently mosquito control activities need to be initiated urgently to reduce the likelihood of transmission. A person with dengue can transmit the virus to mosquitoes within three to four days of contracting dengue. Thus the cycle of transmission may take only 14 days (as illustrated in Figure 4).

Figure 4: Cycle of dengue transmission

Mosquitoes can pass on the dengue virus

8 to 12 days later

Local dengue mosquitoes bite the infected person

(imported case)One person who has travelled overseas and been bitten by an infected dengue mosquito

arrives in Queensland

8 to 12 days later mosquitoes can pass on dengue. One bites YOU.

YOU get sick within 3 to 12 days and can pass the virus on to mosquitoes for up to 12 days after getting sick


The primary risk of contracting dengue is the presence of and exposure to the infective dengue vector. Other parameters that contribute to the increase of risk are:

2 vector density

2 presence of confirmed viraemic cases

2 demographics

2 population density

2 vector/disease pathways.

The DMP is the risk management framework that outlines current best practice in dengue management for the four levels of dengue activity; ongoing prevention, response to sporadic cases, outbreak response and multiple outbreaks.

3.1 Dengue activity levels and responses

Surveillance and control activities are determined by the dengue activity levels as follows (refer Flowchart 1).

Level1 – No current cases: No local transmission of dengue.

Response - Continue routine mosquito and disease surveillance plus community awareness and engagement activities.

Level 2 – Sporadic cases: Cases notified can either be imported cases (clinically suspected or confirmed) or a locally-acquired case (confirmed or not yet confirmed). All dengue positive results require immediate investigation to determine if they are overseas acquired, locally acquired or the pathology result is a false positive.

Response - The objective of mosquito control in response to a sporadic dengue case is to eradicate the dengue virus by killing vectors, where they exist, from up to 200m of ‘dengue case contact points’. ‘Dengue case contact points’ are defined as localities that were visited by a dengue viraemic person during daylight hours, where contact with Ae. aegypti was possible (eg. residence, place of business, school). The dengue case residential location and case contact points are mapped and comprehensive mosquito control activities begun as soon as possible. Emphasis on the public’s role in mosquito control & personal protection via public awareness and engagement is essential. Once a locally-acquired case is confirmed, an outbreak is declared.

Level 3 – Outbreak of dengue: One or more locally acquired confirmed cases occur concurrently in an area. This is a localised outbreak. Dengue cases in Queensland are confirmed by NS1, PCR, viral culture and/or a positive dengue type-specific IgM result. In confirmed outbreaks, cases may be clinically diagnosed where they are epidemiologically linked to a current dengue outbreak.

Response - During an outbreak, activation of the Health Protection Program Incident Management System at the local level maybe considered to support the outbreak response. Most mosquito control responses occur in locations with substantial current dengue activity. Areas with new dengue activity, that may not have been previously surveyed and treated, become a priority. A media communications plan is developed and public awareness activities enhanced.

Level 4 – Large or multiple dengue outbreaks: Substantial outbreaks which threaten local response resources.

Response - A large or multiple outbreak response would require the activation of the Health Protection Program Incident Management System and the establishment of an Incident Management Team to support the outbreak response.

CHAPTER3

Dengue outbreak risk

13Chapter 3 Dengue outbreak risk

Flowchart 1: Dengue Activity Levels and Responses

Mosquito surveillance / public awareness (QH & LG partnership)» Larval and adult surveillance/control in risk areas

and/or hot spots» Consider use of Breteau Index» Dengue zone: larval survey during peak breeding

season annually» Non-dengue zones: larval survey at least bi – annually» Conduct/support training in surveillance and control

methods» Public role in mosquito control emphasised via public

awareness and engagement

Disease surveillance» Clinical and Lab surveillance» Public encouraged via public awareness raising to

report symptoms early if unwell with fever » PHN/PHMO investigates notified cases; determines if

imported or locally acquired» Conduct risk assessment & if necessary escalate to

Level 2

Level 1: No current cases

Enhanced mosquito surveillance & control/public awareness» Coordination between QH & LG» Med Ent conducts risk assessment & maps response areas» Larval control in all premises within 200m of case

contact points (QH & LG)*» Adult mosquito control by QH in all premises within

200m of case contact points* » Continue to emphasise public’s role in mosquito

control & personal protection via public awareness and engagement

*Where vector is present

Disease surveillance & control» PHN case investigation using case report form» Identifies case movements in relation to high risk

areas for transmission» PHMO/PHN, Med Ent, EH and LG, consult re mosquito

control response» If case confirmed as locally acquired escalate to

Level 3, outbreak declared» Public encouraged via public awareness raising to

report symptoms early if unwell with fever

Level 2: Sporadic cases

Case is confirmed as locally-acquired Consider activation of the HPPIMS at the local level, PHUs work together: » To inform District Manager (activate core funding), Senior Director CDB, LG and local GPs, Emergency Depts and local

laboratories to enhance awareness and prompt early case reporting» PHN/PHMO staff implement contact tracing and active case finding» Med Ent staff assess, coordinate and manage vector control in collaboration with Local Govt» Enhanced mosquito surveillance and control undertaken as above in current and new dengue activity areas» Develop media communications plan» Enhanced public awareness activities encouraging residents to reduce domestic mosquito breeding sites, use personal

protection & present early if unwell with fever

Level 3: Dengue outbreak

Establish HPPIMS:» Public Health Incident Controller appointed» Establish Public Health Emergency Operations Centre» Consider activation of the Health Protection Sub Plan to QLD Health Disaster Plan» Implement the dengue management plan for large or multiple outbreaks» Establish Incident Management Team to plan and coordinate response» Commence enhanced mosquito and disease surveillance and control measures as above» Enhanced media and public awareness campaign

Level 4: Large or Multiple outbreaks


3.2 Stakeholders and their roles

Control of dengue mosquitoes in urban and commercial environments is the responsibility of the public and local government. Queensland Health becomes involved as the lead agency whenever there is a dengue outbreak.

3.2.1 Local Government

Local governments are delegated with the responsibility of administering sections of the Public Health Act 2005 and Public Health Regulation 2005 which relate to mosquitoes and mosquito breeding sites. The pertinent sections of the act and regulation dealing with local government public health risk are administered and enforced primarily by local governments (Refer to the below link for further details).

http://www.health.qld.gov.au/eholocalgov/secure_area/publichealthact2005/resource_kit.asp

Many local governments conduct scientifically based mosquito management programs based on Integrated Pest Management. These programs include elements of chemical and biological control, habitat modification and public education. Other local governments rely on health education and/or limited treatment of known breeding sites to control mosquitoes. Local governments are ideally placed to carry out mosquito management within their own areas. In addition to having knowledge of local conditions conducive to mosquito breeding, many have access to resources or the ability to acquire resources for conducting mosquito control operations e.g. insecticide application equipment, appropriate vehicles and staff.

3.2.2 Queensland Health

Queensland Health is responsible for setting strategic direction and implementing actions for the prevention of and response to dengue outbreaks in Queensland. This includes:

2 investigating notifications of dengue virus infections

2 monitoring incidences of dengue in Queensland

2 leading dengue surveillance and emergency vector control activities in dengue receptive areas in Queensland

2 coordinating, supporting and assisting local government with the implementation of mosquito surveillance and control activities for dengue mosquitoes through a partnership arrangement

2 leading public awareness activities to promote self-protective behaviours by the public, including reducing mosquito breeding places around the home and businesses

2 monitoring the distribution of dengue vectors and conducting pesticide resistance testing on dengue vectors where relevant in Queensland

2 supporting local government through the provision of specialised training in mosquito identification, surveillance and control methods, and medical entomology support

2 development of relevant public health legislation and monitoring and supporting it’s administration.

3.2.3 Australian Quarantine and Inspection Service (AQIS)

AQIS is responsible for detection of exotic mosquitoes on behalf of the Department of Health and Ageing (DoHA) at international first ports of entry into Australia. AQIS is also responsible for maintaining an exotic mosquito exclusion zone of 400 m around first ports of entry. Where private residential property is located within the 400 m zone, AQIS liaises with local government to plan appropriate surveillance and control measures in the event of an incursion by an exotic mosquito.

15Chapter 4 Mosquito surveillance and control

Prevention and control of dengue mosquitoes is the cornerstone for a successful dengue prevention and control program. A sound and practical vector surveillance program allows control efforts to be targeted more efficiently. Local governments in Queensland have responsibility for enforcement of the legislation (the Public Health Act 2005 and Public Health Regulation 2005) relating to public health risks posed by mosquitoes.

4.1 Dengue mosquito surveillance

Queensland can be divided into three areas:

2 dengue receptive areas - areas where dengue outbreaks are common (i.e. dengue vectors are prevalent and there is a history of outbreaks instigated by viraemic travellers)

2 dengue potential areas – areas where dengue mosquitoes are present, but there is limited contact with viraemic travellers

2 dengue-free areas – areas with no recent history of vectors, so transmission is not possible even when there are viraemic travellers.

Surveillance activities in ‘dengue receptive areas’ are designed to detect the relative abundance of Ae. aegypti in cities and towns that are prone to dengue outbreaks (particular Cairns, Townsville and Thursday Island). Mosquito surveillance should be conducted as a routine program in those areas of the town or city at highest risk of dengue outbreaks.

Surveillance activities also provide an early warning system for the possible importation of Ae. albopictus. Due to the prevalence of dengue mosquitoes in north Queensland, there is an emphasis on adult monitoring as a direct measure to assess dengue risk (refer 4.1.2). Routine surveillance programs are undertaken in high-risk areas and venues using a variety of methodologies including BioGents Sentinel adult traps (BGS traps), sticky ovitraps and PCR testing for dengue mosquitoes (refer Appendix 6).

Surveillance activities in dengue potential areas and dengue-free areas are designed to detect the presence and/or the relative abundance of Ae. aegypti in that city or town. Ideally, surveys of domestic yards should be carried out in dengue potential areas every year and dengue free areas biannually, during a ‘mosquito inspection program’. These programs should take place during the peak mosquito breeding period, usually January to March.

Surveillance data is used to evaluate the risk of dengue transmission. Data collected should be of a consistent high quality, standardised and kept in a format for ease of future reference. Property inspection details should be supplemented with mapping of high-risk areas, the locations surveyed and key premises within the high-risk areas identified.

4.1.1 Larval surveillance

Larval survey is the recommended survey method for a ‘mosquito inspection program’, and is conducted with the occupiers consent, unless under an ‘authorised prevention and control program (Public Health Act 2005) (refer 4.2).

Larval surveys will identify the density of the vector, and the available breeding sites on the ground (NOTE: will not detect subterranean, roof gutter or rainwater tank breeding sites).

In non-outbreak situations, larval surveillance involves locating and mapping areas likely to have containers that could breed Ae. aegypti. Mosquito inspections are then conducted in these areas to locate containers capable of holding water, in addition to sampling and controlling larvae (refer Appendix 8 and 9).

CHAPTER4

Mosquito surveillance and control


A variety of methods are available for the inspection and sampling of mosquito larvae. These are tailored for specific container types. For instance, the funnel trap was designed to sample wells and mine shafts, and a small aquarium net can be used to sample tyres. Tyre traps are used by AQIS and can provide an effective surveillance tool in remote areas with limited resources. Generally, most containers are small and can be readily sampled using a turkey baster or large bulb pipette. The water is then placed into a small white tray and mosquito larvae picked with a small pipette and placed in a 5 ml plastic vial for identification. In areas where Ae. aegypti is established, a sub-sample of larvae (5-10) from each breeding site will be adequate. For areas without recent Ae. aegypti activity, the aim is to collect as many larvae as possible. Larvae should be placed into a small labelled vial for transport. Larvae should be preserved in 70% ethanol and identified within 24 hours. Pertinent data (premise address, date, container type, larval identification, etc.) should be recorded in a vector control database.

Collection data enables the calculation of various mosquito indices (refer Appendix 7). For example, Queensland Health use the Breteau Index (Appendix 8) to provide a relative measure of the abundance of containers breeding Ae. aegypti per 100 houses. Although the Breteau Index does not reflect the true Ae. aegypti productivity, it does provide a relative index of Ae. aegypti breeding sites.

While the presence of Ae. aegypti indicates a risk of dengue fever transmission, the level of the risk depends on the density of this vector as indicated in the WHO Density Figure (WHO 1972).

While larval surveys are the recommended survey method for a mosquito inspection program, they should be supplemented with adult mosquito surveillance whenever possible.

4.1.2 Adult mosquito surveillance

Traditional dengue mosquito surveillance involves inspecting commercial and domestic yards and premises for mosquito breeding containers. However, in north Queensland BGS traps and sticky ovitraps are used to monitor adult Ae. aegypti in high risk areas for dengue transmission. BGS traps are also being deployed in other areas in Queensland to successfully monitor for Ae. aegypti. Large numbers of these traps can be used in a surveillance network to locate ‘hotspots’ of elevated dengue mosquito populations and thus target inspections. Property occupants should be informed about steps they can take to prevent mosquito breeding during these surveys.

Selection of surveillance location in cities or towns

Queensland Health, local government or Indigenous community council workers should attempt to control Ae. aegypti breeding sites by identifying and prioritising areas likely to have breeding containers according to type of venue and geographical hotspots;

High/medium risk venues:

2 backpackers/hostels/guest houses

2 hospitals

2 tyre dealers

2 schools (pre-schools, primary, high schools, TAFE colleges, day-care centres)

2 travel transit centres.


Geographical hot spots:

2 older areas of town with non-screened housing (especially with a history of high Ae. aegypti numbers)

2 areas that have had previous dengue activity

2 industrial areas (especially if there are tyre yards and wreckers)

2 Torres Strait island communities with high numbers of potential mosquito breeding sites.

Selection of premises

The Premise Condition Index (PCI), developed by the Queensland Institute of Medical Research (QIMR), is a shorthand way of estimating if a property is likely to breed Ae. aegypti. The index consists of three components, each of which is scored from 1 to 3:

2 house condition

2 yard condition

2 amount of shade.

High scores reflect untidy houses and yards, along with more shade. Premises with a poorly maintained house, a cluttered yard and lots of shade are more likely to have containers that will breed Ae. aegypti than a new house with a spartan, shadeless yard. The PCI is assessed from the street, a record of high PCI houses and areas can be used to target surveillance.

If it is not practical to check all three of the above noted components, the amount of shade coverage should be used as a criterion to select premises to inspect for mosquito larvae.

If Ae. aegypti are found they should be controlled immediately using the methods described in section 4.2. This may prevent the mosquito from becoming established in these areas. A ‘pest control advice’ (refer Pest Management Act 2001) may need to be provided. If Ae. albopictus is detected or suspected Queensland Health must be notified urgently to initiate emergency response protocols.

Number of premises to be inspected

The properties selected for inspection should be based on high PCI values in high risk areas. Between 30 - 100 premises should be inspected during a mosquito inspection program depending on the size of the town or city.

4.1.3 Resources

Surveillance activities appropriate to the resources available have been grouped as follows.

Limited resources (No vector control team):

2 set tyre traps once or twice a year, inspect one week apart and collect larvae if found and send to Qld Health

2 conduct larval surveys during a mosquito inspection program of high-risk venues and geographic hot spots at appropriate intervals

2 set BGS traps if available to detect adult Ae. aegypti.


Moderate resources (Small vector control team):

2 conduct a mosquito inspection program at appropriate intervals which cover a large sample of premises including high-risk venues and hot spots

2 set and retrieve monthly ovitraps and hatch eggs on paddles to detect Ae. aegypti larvae (Standard ovitraps require rearing of larvae in a lab setting)

2 set BGS traps once a month to detect adult Ae. aegypti.

Full resources (Large vector control team):

2 conduct larval surveys at appropriate intervals covering 100 premises or a large sample area including high risk venues and hot spots in conjunction with a combination of adult traps and sticky ovitraps

2 set adult traps weekly or monthly.

4.2 Dengue mosquito control

Queensland legislation (Pest Management Act 2001) requires all mosquito control activities involving the application of pesticide to be conducted by a licensed pest management technician, with the exception of the application of s-methoprene pellets and briquettes, and the deployment of prescribed lethal ovitraps (refer 4.2.2).

Where legislative support is required to facilitate control measures, an Authorised Prevention and Control Program, Public Health Act 2005 can be declared by the chief executive of Queensland Health. This enables authorised officers (e.g. vector control officers, environmental health officers, environmental health workers, medical entomologists) from local councils and/or Queensland Health, to enter yards and conduct mosquito control activities. Consent to enter yards must be sort as a matter of course, however authorised officers under an Authorised Prevention and Control Program can enter yards and proceed without consent in the absence of the occupier if necessary.

Upon receipt of a dengue notification (pending or confirmed) a risk assessment of dengue transmission will be conducted, and appropriate mosquito control response areas mapped. Multiple variables must be considered when assessing the risk of dengue transmission. Medical entomologists specialise in knowledge on linking both the disease agent and the biology of the vector. The response area depends greatly on the notification timeframe for a viraemic person, the duration of time at an address, the presents of the vector in the area and an awareness of the environmental conditions. Mosquito control activities can, if implemented promptly, limit the extent of dengue outbreaks. Control activities include:

Larval control

Conducting intensive inspections of all yards and controlling mosquito larvae in all containers within at least 200 m radius of the case residence and any other places where infected person visited during viraemic periods (e.g. place of business, school etc).

Adult control

Controlling adult Ae. aegypti with a combination of ‘lure and kill’ trapping and interior residual spraying. Internal residual spraying is usually limited to the viraemic contact address(s), nearest neighbours and other high-risk properties. The ‘lure and kill” ovitraps will be deployed within 200m radius of the case residence and high risk contact areas (refer Appendix 6).

Community engagement

Actively engage the public to take simple measures to reduce mosquito breeding sites around the home and workplace.


4.2.1 Larval control

Larval control consists of the removal and/or insecticide treatment of containers that are breeding or could potentially breed Ae. aegypti. Any chemical treatment must be consistent with label recommendations. In non-outbreak situations, yard-to-yard surveys are conducted in high-risk venues and geographical hot spots. Larval control activities include the following:

Source reduction

Containers that can collect water in the yard and in / or under houses are emptied and rendered ‘mosquito-proof’ (e.g. turned upside down, or filled with sand to prevent water collection) or destroyed. Further measures include filling of tree holes with a sand and mortar mix and recommending house occupiers to remove excessive numbers of bromeliad plants which hold water.

Rainwater tanks must be screened (less than 1mm aperture on gauze) to comply with Public Health Regulation 2005.

Chemical application

Any chemical treatment or application must be consistent with label recommendations.

Prolink Pellets® containing the insect growth regulator (S)-methoprene can be thrown into hard-to-inspect containers that can breed mosquitoes (eg. wells, drain sumps and roof gutters, especially those with overhanging trees). Prolink Pellets® offer residual activity of one month duration due to the slow release formulation and a low non-target toxicity.

Some cockroach surface sprays are registered for use on mosquitoes. Treatment of containers with an appropriate surface spray will kill pupae and any resting adult mosquitoes for several months. Sustained use of surface sprays is discouraged, due to concerns of the development of chemical resistance.

Natural breeding sites that hold water, such as tree holes and bromeliads, can be treated with the previously described insecticide products.

Prolink XR-Briquets® containing (S)-methoprene are a residual slow release formulation block, lasting approximately 3 months registered for use in rainwater tanks to prevent emergence of adult mosquitoes. These have been used to treat rainwater tanks in the Torres Strait and should be viewed as a temporary measure until tank screens can be repaired to comply with Public Health Regulation 2005.

Biological control

Biological control using copepods has been successfully employed in Charters Towers and Townsville. Copepods are minute crustaceans that devour young mosquito larvae. They occur naturally in ponds and lakes where they can be collected and used to seed large subterranean containers such as service pits and wells. They are not suitable for use in surface containers.


4.2.2 Adult Mosquito Control

Research in Queensland indicates that a 200m radius focal control area is usually appropriate, particularly if control activities are initiated within four days (one gonotrophic cycle of Ae. aegypti) of the suspected case becoming viraemic or entering the area.

Interior residual spraying

An effective way to kill adult mosquitoes is to apply a residual insecticide onto the areas where they prefer to rest. Ae. aegypti prefer to rest in dark areas inside and under houses and buildings. Favourite resting spots are under beds, tables and chairs; in wardrobes and closets; on piles of dirty laundry and shoes; inside open boxes; in dark and quiet rooms; and even on dark objects such as clothing or furniture.

Interior residual spraying of houses is an effective, but relatively slow process. A residual insecticide (the synthetic pyrethroid bifenthrin, deltamethrin or lambda-cyhalothrin) can be applied as a surface spray in premises in response to dengue notifications. Occupants are provided with information about the chemicals and safety precautions. Permission to spray must be granted before treating and pest control advice provided to the occupant. All commercial residual insecticides must be applied by a licensed pest management technician.

Interior residual spraying has been greatly reduced for dengue interventions in north Queensland since 2004, due to its inability to compare with the speed of lethal ovitrap deployments (see below) and concerns about the amount of insecticide applied to the domestic environment during large outbreaks. Preliminary research detected potential resistance to some synthetic pyrethrins (permethrin, cypermethrin) in dengue mosquitoes in some Cairns suburbs. Queensland Health does not recommend large-scale use of surface sprays for routine mosquito control due to the potential for Ae. aegypti developing resistance to pyrethrin insecticides.

If domestic insecticides are used around the house by residents they must be used as directed on the label.

Although external truck-based ‘fogging’ is popular internationally, and highly visible, it is not effective at eliminating dengue.

Lure and Kill Ovitraps

Sticky and lethal ovitrap (‘Lure and Kill’ ovitraps) strategies have been used with great success since 2004 by the Dengue Action Response Team (DART) from the Tropical Regional Services of Queensland Health (refer Appendix 6).

Lethal ovitraps provide a ‘green’ alternative to dengue mosquito control due to the minimal use of pesticides, minimal contact with non-target insects/animals/humans, and minimal chemical exposure of health workers to pesticides during dengue outbreaks. This strategy has proven to be a breakthrough, allowing rapid treatment of areas without using large doses of insecticide.


4.2.3 Evaluation of the mosquito inspection programs outside dengue receptive areas

Larval surveys should be conducted once a year during the warm months (November-April) to assist in evaluating previously conducted mosquito inspection programs. All premises previously found with Ae. aegypti as well as all premises within a 200 metre radius of the premises found with Ae. aegypti should be surveyed. Premises in high-risk venues and hot spots should also be included. If resources are available, include the deployment of adult traps at the same time as the larval survey.

Calculate the density of dengue mosquitoes and if the transmission risk-level remains high, continue the control program and public awareness campaign, focusing on the need for residents to reduce breeding sites around the house and business premises. Continue this approach until dengue mosquito density falls to a low transmission risk level. A continued suppression approach in many cases can lead to the eradication of Ae. aegypti.

4.2.4 Eradication programs for dengue vector species

Establishment of eradication programs for Ae. aegypti or Ae. albopictus in cities or towns where the mosquito has not previously been found, would require specific agreement between Queensland Health, local government and other key stakeholders to define roles and responsibilities. This is due to the high resource implications of funding the dedicated staff and equipment required. Such a program would also need ongoing surveillance and control measures to prevent re-invasion of Ae. aegypti from other locations. An eradication program would require the initiation of an ‘authorised prevention and control program’ for the defined area.


This section focuses specifically on the public health aspects of surveillance, confirmation and notification of human cases of dengue. This section does not discuss the medical treatment of symptomatic cases. Medical officers wishing to access dengue treatment protocols should contact their local Queensland Health public health medical officer or infectious diseases physician.

5.1 Routine disease surveillance

Routine disease surveillance is the first defence against dengue. Over the past five years there has been a shift in emphasis from ‘dengue surveillance’ to surveillance for ‘imported cases’ of dengue. This is because dengue outbreaks are started by an often unrecognised viraemic traveller (i.e. an imported case). Surveillance for dengue encompasses clinical and laboratory surveillance.

5.1.1 Clinical surveillance

Effective disease surveillance relies on general practitioners, emergency department doctors and laboratories notifying Queensland Health of possible cases of dengue, particularly in people who have recently arrived from tropical countries. Doctors are required under the provisions of the Public Health Act 2005 to notify public health units (PHU) immediately upon clinical suspicion, rather than waiting for laboratory results.

Due to the risk of a viraemic traveller initiating an outbreak, surveillance for clinical cases of dengue is very important. If a viraemic overseas visitor does not have medical travel insurance to cover the costs associated with seeking medical assistance a delay in presentation may result. This could be a barrier to effective surveillance. If this situation arises and impacts negatively on effective outbreak management, local discussions may need to take place to explore a resolution. Early presentation and notification of cases enables action to be taken promptly to reduce the risk of local transmission.

If the patient does not have a travel history, this may indicate that the patient became infected by a dengue-infected mosquito in their local area (local transmission), and therefore the area may be in the early stages of an outbreak. Any delay in notification of suspected dengue can mean the difference between managing a sporadic case of dengue and managing an outbreak with multiple cases. Patients with dengue should be advised to take measures to avoid being bitten by mosquitoes while they are sick.

5.1.2 Diagnostic (Laboratory) testing

There are several types of tests to diagnose dengue. The suitability of each test depends on the timing during the illness that a blood sample is collected. Some tests are more appropriate in the early stages of dengue and some are appropriate for later stages of the illness.

It is very important that the appropriate tests are requested. The suitability of each test depends on the timing of the blood sample collection in relation to when the case became unwell. PHU staff can assist medical practitioners to determine the appropriate tests to order.

Table 2 shows the types of tests for laboratory confirmation of dengue depending on the timing of the onset of the illness.

CHAPTER5

Disease surveillance

23Chapter 5 Disease surveillance

Table 2: Tests for laboratory confirmation of dengue

TEST TYPE PCRNS1

ELISA IgM IgG

Days after onset

of symptoms0-5 days 0-9 days From day 5 onwards From day 8 onwards

NOTE: Clients tested on day 4 to 6 post onset of symptoms may require both PCR and IgM.

Doctors who are treating patients who live or work in geographical ‘hot spots’ for dengue need to be particularly aware of the importance of testing and notification. Refer to Appendix 2 and 3 for details of dengue laboratory confirmation tests and examples of testing anomalies.

5.1.3 Barriers to effectively diagnosing dengue

The confirmation of dengue cases assists Queensland Health to identify and track the extent of an outbreak and to prevent further cases occurring. It is important for a patient to have a correct laboratory diagnosis of their illness. Early detection of dengue cases can be delayed for the following reasons:

2 cases may not seek prompt medical attention

2 high number of transient doctors who may be unfamiliar with the disease (as dengue is mostly experienced in north Queensland)

2 doctors may not understand the range of clinical symptoms possible (mild to severe), resulting in milder cases not being recognised

2 doctors may not be aware of their legislative responsibility to notify suspected dengue cases to Queensland Health

2 doctors may not request tests during an outbreak because they may be confident of diagnosing dengue clinically. Some doctors may not be aware of the value of laboratory confirmation

2 doctors may not be aware of the correct tests to request for dengue.

5.2 Disease surveillance and response for sporadic cases

5.2.1 Case investigation

For every confirmed dengue notification an attempt should be made to interview the patient and determine the travel history. If the case is notified in a dengue receptive area enhanced surveillance should be carried out using the Case Report Form (See Appendix 3 for a DRAFT copy).

This form records the patient details and other key information to determine the risk for local dengue transmission including:

2 the clinical signs and symptoms

2 laboratory tests ordered and results, including the full blood count (a substantial thrombocytopenia often occurs in dengue)

2 the patient’s recent travel history (e.g. from dengue endemic countries or from an area in Queensland currently experiencing dengue activity)

2 the patient’s recent movements (e.g. to high-risk premises such as a backpacker hostel or hospital).


5.2.2 Assessment of the risk

The assessment is usually undertaken by Queensland Health staff, which may include the public health medical officer (PHMO), public health nurse (PHN), medical entomologist (ME), or the relevant Director of Environmental Health Services (DEHS). In north Queensland there is a dedicated Dengue Action Response Team (DART) that can provide additional information to assist in assessing transmission risk following discussions with residents.

Queensland Health will liaise with the treating medical practitioner and the laboratory to ensure that the necessary laboratory test(s) are performed on suspected cases as soon as possible. If the blood sample has been collected within the first five days of illness and it has been shown to be IgM negative, PCR or NS1 will be requested on an urgent basis.

If the sample is IgM positive, confirmatory test(s) will be undertaken by Queensland Health Forensic and Scientific Services (QHFSS), also on an urgent basis. QHFSS may confirm a result as dengue infection using flavivirus-specific IgM EIA. If the result is negative a further blood sample may be requested. If relying on serology tests alone, follow up IgM is requested more then seven days after onset to compare acute and convalescent IgM results.

Resume normal surveillance and control measures if all results are negative (refer to Section 3.1 – Dengue Activity Levels and Responses).

When an imported case is confirmed as being viraemic in a high or medium risk area all medical practitioners that provide services in that risk area should be informed. They will be advised to consider dengue in the differential diagnosis of people with a febrile illness, to arrange for urgent dengue tests and to promptly notify Queensland Health of any clinically-suspect cases. Delays in notification may allow local transmission of dengue to occur undetected.

Flowchart 2: Notification and follow up of sporadic cases by PHU, CDC staff

Laboratory Diagnosis Practitioner Diagnosis

PHN/PHMO from local public health unit notified

PHN/PHMO liaise with the referring practitioner in order to interview patient

PHN/PHMO interviews patient and completes the Case Report Form

PHN/PHMO consults with the DEHS who consults with the medical entomologist and LG regarding the need for mosquito control response

If the case is confirmed as locally-acquired PHU’s work together to inform:Public Affairs/Health Promotion, District Manager, Senior Director CDB, local government,

Local GPs, Emergency Dept doctors, local laboratories, PHU colleagues and the public

25Chapter 5 Disease surveillance

Flowchart 2 illustrates the procedure followed by Queensland Health when a clinically suspected l ocally-acquired case of dengue is reported or an imported case of dengue (either clinically suspected or laboratory-confirmed) is reported.

5.3 Surveillance for outbreak response

5.3.1 Dengue case management

During an outbreak, Queensland Health will advise general practitioners (GPs), hospital emergency departments and local pathology laboratories to be on alert and immediately report dengue cases and/or pathology results consistent with dengue. The public will also be alerted to seek medical attention early if displaying symptoms consistent with dengue infection.

Medical practitioners should continue to request dengue testing for suspected cases throughout the duration of the outbreak.

The Case Report Form (See Appendix 3 for a DRAFT copy) should be completed for all suspected and confirmed cases, including notification of cases outside of the outbreak area.

Flowchart 3 illustrates the procedures to be followed by Queensland Health upon recognising an outbreak of dengue.

Flowchart 3: Procedures for outbreak case notification

PHN/PHMO consults with DEHS, medical entomologist, Senior Director Regional Services, local government and Public Affairs

PHN/PHMO, medical entomologist and DEHS map the dengue Warning Area and plan immediate action with local government

PHU & local government commence Ae. aegypti control activities including house-to-house larval and adult mosquito control

5.3.2 Laboratory notification

Dengue is a notifiable condition under the Public Health Act 2005 in Queensland and laboratories are required to notify Queensland Health of positive dengue results.

Queensland Health Forensic and Scientific Services (QHFSS) is the arbovirus reference laboratory for Queensland. Dengue tests are also performed by private and public laboratories in Queensland.

Dengue virus genotyping

QHFSS is now able to genetically track the potential origins of outbreaks. These origins are then illustrated in a phylogenic tree which, like a family tree links the genetic relatedness of different dengue viruses.

This technology allows scientists to determine whether dengue outbreaks are likely to be related. For example, there were two dengue 2 outbreaks in Cairns in 2003, and genotyping of the dengue isolates revealed that the two outbreaks were not caused by the same virus. One was genetically similar to a virus circulating in PNG and the other was similar to a virus circulating in Thailand.


5.3.3 Data management

All confirmed dengue cases should be recorded on a system that can be used by all relevant personnel in disease surveillance, mosquito surveillance, prevention and control and environmental health. Summary reports should list the distribution of dengue by suburbs, range of symptoms and highlight the latest cases to help track the outbreak.

All clinical notifications from areas outside the known outbreak areas should be investigated.

Queensland Health will maintain a ‘timeline log for each outbreak’ including the essential dates, cases and activities. The timeline log serves as important reference material when the outbreak is eventually reviewed. An example of a timeline is shown in Appendix 4.

27Chapter 6 Managing large or multiple dengue outbreaks

During large or multiple dengue1 outbreaks, the activation of the Health Protection Program Incident Management System (HPPIMS) is the framework endorsed by Qld Health, to support operational functions. This would result in the appointed Public Health Incident Controller (PHIC) working with the Designated Executive to establish an Incident Management Team (IMT) and oversee the ongoing management of the outbreak. The IMT could operate at either state or area level depending on the extent or risk of extent of the outbreak. The objective of establishing a HPPIMS is rapid outbreak control through the implementation of a centrally coordinated and supported response framework.

6.1 HPPIMS activation

The HPPIMS may be activated when:

2 local resources are insufficient to manage the outbreak response

2 there is a risk that the outbreak could spread to other areas

2 there is significant public health concern about the outbreak

2 there is significant political concern about the outbreak

2 the outbreak response requires significant additional financial support

2 on request from the PHMO or medical entomologist managing the outbreak response at the local level.

6.2 Relationships with other agencies and the public

6.2.1 Local government

Local government have the legislated authority under the Public Health Regulation 2005 to enforce legislation that makes it an offence for households to allow mosquito breeding on the premises.

During a dengue outbreak local government may be called upon to assist Queensland Health in minimising disease transmission by actively engaging and supporting the public and industry to reduce mosquito breeding sites in areas identified as actual and potential high risk for escalating and/or maintaining the outbreak.

6.2.2 General practitioners, other medical and laboratory staff

Early detection and notification of a suspected dengue case is essential for interventions to be successful. General practitioners, hospital accident and emergency staff and laboratory staff are therefore core partners in dengue response initiatives. Public health medical officers from public health units will liaise directly with directors of hospital accident and emergency departments.

During a large or multiple dengue outbreaks General Practice Queensland (GPQ) will be called upon to support engagement with general practitioners via local Divisions of General Practice.

6.2.3 General public

Media alerts provide specific health protection advice to the general public and residents in the dengue alert areas.

1 For the purposes of the DMP, multiple outbreaks can be defined as substantial outbreaks which occur simultaneously in two or more separate locations and outstrip local resources.

CHAPTER6Managing large or multiple dengue outbreaks


6.3 Concept of operations

6.3.1 Health service operations

Response to human cases of dengue will be as per sections 5.2 and 5.3 of this plan.

6.3.2 Mosquito surveillance and control

During large or multiple outbreaks, procurement of resources to enable expanded mosquito control responses, must be carefully prioritised by the HIC in consultation with the medical entomologists and local government.

Priority must be given to locations where:

2 there is a high risk that the outbreak could become substantial

2 substantial dengue activity has occurred previously (particularly where the prior dengue activity was a different strain to the current strain)

2 there is known to be intense mosquito breeding (e.g. older, unscreened open houses such as Queenslanders)

2 the outbreak could spread rapidly to other areas (e.g. an outbreak in Torres Strait islands spreading to Cairns or Townsville or an outbreak in industrial areas spreading to urban areas)

2 there are suspected dengue cases, but confirmed dengue cases have not recently been reported in the area

2 additional serotypes are detected in an area.

The level of mosquito control responses and entomological interventions required will be determined according to the level of priority and staffing levels (see below).

6.3.3 Documentation and data collection

Information on numbers and demographics of cases must to be recorded and reported to NOCS. Data on mosquito breeding sites and vectors including house location, adult/larval counts and control measures is to be accurately recorded.

6.3.4 Staffing requirements

Public health regional services must plan for staffing levels and skills mix that would be required to lead a large or multiple dengue outbreaks. It is often necessary to second additional staff from other Queensland Health districts or from elsewhere in Queensland during multiple or prolonged outbreaks. Staff seconded for large scale response activities may include EHOs, nurses, local government staff, data officers, medical entomologists and vector control officers. It is essential that seconded staff have the necessary skills and legislative authority, where required, to undertake the duties for which they have been seconded. Outbreaks can escalate very quickly, so ideally a pool of relief staff must be identified and maintained during non-outbreak periods.

29Chapter 6 Managing large or multiple dengue outbreaks

6.3.5 Workplace health and safety

Refer to the Environmental Health Practicians Online Manual for workplace health and safety guidelines for use during an dengue outbreak;

http://qheps.health.qld.gov.au/ehpom/documents/dengueinduwkphlthsaf.pdf

6.3.5 Staff training

All staff who will undertake a role in case investigation, public media, and mosquito surveillance and control programs must be offered training in these areas, as required, prior to commencing duty.

Training for staff sourced from other areas to assist the outbreak response must be developed.

6.3.6 Communication

Regular communication is particularly important during large or multiple outbreaks, as high levels of dengue activity increase the risk of outbreaks expanding or being transported to other high-risk areas. The IMT will provide external stakeholders (e.g. GPs, private hospitals, local government, and private laboratories) with regular advice on the outbreak status as well as establishing a forum with key stakeholders to ensure consistency of messaging to the general public.


The prevention of dengue is the responsibility of both government (state and local) and the public. Mosquito control workers cannot eliminate mosquito breeding in all homes and businesses in Queensland, hence an important element of dengue management is raising public awareness about the community’s role in eliminating mosquito breeding at home and in the workplace as well as supporting positive behaviour change around personal protective practices. This can be achieved through targeted awareness campaigns and community engagement strategies.

7.1 Routine public awareness and community engagement

Raising public awareness during non-outbreak periods involves informing the general public about the risk of outbreaks, the importance of regular mosquito control, and practical steps that can be taken around the home and workplace to reduce mosquito breeding sites. Population level awareness strategies are designed to create and maintain awareness and motivation within the community. Messaging should convey a positive view of empowerment supporting personal responsibility and action rather than creating fear or panic.

Enhanced community awareness about dengue is supported via varying modalities including appropriate information, education and communication (IEC) materials, media advertising and promotional events which target community members, schools, workplaces and relevant industries. The Queensland Health dengue website also provides a valuable medium for information exchange: www.health.qld.gov.au/dengue.

Community engagement strategies strengthen community awareness and supports positive behaviour change around dengue prevention. Engagement strategies should be planned and implemented in collaboration with key stakeholders, particularly local government. Community engagement strategies could include;

2 formal agreements with government departments and/or industry representative bodies to implement dengue preventative initiatives

2 partnerships with public interest and community groups to provide access to simple, affordable and achievable measures to reduce mosquito breeding sites in and around the workplace and home as well as access to personal protective measures.

In the current dengue receptive zone (north Queensland), public awareness strategies are enhanced just before and throughout the north Queensland wet season (December-April). These strategies are more targeted, and may include:

2 media liaison and media releases

2 media conferences featuring media-trained, authoritative spokespeople

2 advertising (TV, radio and print)

2 promotional stands at public events.

Key preventive messages include:

2 disease facts and myths

2 seek medical attention promptly if unwell with a fever

2 positive dengue-protective behaviour (e.g. clean up yards, tip out or dispose of unwanted containers, clean gutters, use personal insect repellent, screen houses etc)

2 public’s legal responsibility regarding domestic mosquito breeding.

CHAPTER7Public Awareness and Community Engagement

31Chapter 7 Public awareness and community engagement

In non dengue receptive areas there is also a need to support the general public to reduce container breeding mosquitoes as a prevention measure. This may necessitate the development of public awareness resources that identify the general benefit of reducing mosquito breeding around the house without specifically focusing on dengue.

7.2 Public awareness in response to sporadic cases

Specific community awareness initiatives should be targeted at occupants of premises in the immediate vicinity of the dengue case. The objective is to heighten awareness of the risk of local transmission of dengue in the immediate vicinity of the dengue case and urge occupants to take immediate steps to control Ae. aegypti.

In general the media is rarely informed of sporadic cases. If the media does become aware of the sporadic case, Queensland Health will prepare a response reassuring the public of the preventive steps being taken by Queensland Health, local government and Indigenous community councils.

7.3 Public awareness in response to an outbreak

During outbreaks public awareness programs are intensified. Queensland Health public affairs and health promotion staff inform the public of outbreak details. Communication strategies aim to heighten public perception of immediate risk and motivate the public to take positive preventive action.

Geographic hot spots targeted for intensive public awareness activity are classified as follows:

Dengue Warning Area - this classification is used for suburbs where local transmission has occurred recently (in the past four weeks) and is delineated by specific geographical boundaries.

Dengue Watch Area - this classification is used for all suburbs or towns that are at risk of local transmission during outbreak periods. For a few cases of local transmission, the Dengue Watch Area may be neighbouring suburbs. For a serious outbreak, the Dengue Watch Area may cover a whole Queensland Health service district.

Public awareness activities involve informing the public of potential dengue outbreaks, providing updates on current outbreaks and providing information on simple measures to reduce the risk of dengue transmission. Activities include:

2 media liaison and media releases

2 advertising

2 customised media plan for probable cases

2 media conferences featuring trained, authoritative spokespeople

2 requesting media spokespeople from Divisions of General Practice and local government to reinforce messages

2 keeping the dengue website updated

2 keeping relevant agencies (e.g. tourism bodies) informed of public relations activities to promote collaboration and minimise the risk of negative reactions to media and other dengue control strategies

2 preparing departmental briefings.


In addition, residents and businesses (e.g. tyre yards, construction sites and backpacker accommodation) in the dengue watch area are informed of the potential risks and provided with information outlining prevention and protective measures. Queensland Health, local government and Indigenous community councils also conduct one-to-one information exchange sessions with residents in the dengue warning area. For some establishments (eg. hospitals, schools) customised dengue mosquito control programs are developed.

Key outbreak response messages include:

2 importance of seeking timely medical advice for those with symptoms of dengue

2 signs and symptoms of dengue

2 map of dengue warning areas

2 tally on number of cases

2 results of mosquito surveys

2 preventative and protective measures.

7.4 Health promotion research and evaluation

Understanding and influencing public behaviour regarding dengue protection is an important requirement for successful dengue prevention and outbreak control.

Queensland Health works collaboratively with tertiary institutions and research organisations to periodically measure the public’s knowledge, attitudes and behavioural practices towards dengue prevention and control. This may consist of focus group discussions to measure attitudes towards dengue or to pilot a new/adapted education resource. Surveys are also conducted to measure media campaign recall after a dengue wet season. Survey results are used to formulate community engagement approaches, review and / or develop new education resources as well as supporting dengue prevention funding.

7.5 Professional education and staff training

Queensland Health facilitates training when required covering varying aspects of mosquito surveillance and control. During an outbreak, relevant in-service training in collaboration with infectious disease physicians may be arranged for clinicians and laboratory staff from hospitals and clinics outside of major referral hospitals. The north Queensland Workforce Unit has dengue resources designed specifically for community health staff, including rural and remote registered nurses and Indigenous health workers.

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Gubler DJ (1997). Dengue and dengue haemorrhagic fever: its history and resurgence as a global public health problem. In: Dengue and Dengue Hemorrhagic Fever. DJ Gubler and GK Kuno eds, CAB International 1997.

Hanna JN, Ritchie SA, Merritt AD, van den Hurk AF, Phillips DA, Serafin IL, Norton RE, McBride WJH, Gleeson FV and Poidinger M (1998). Two contiguous outbreaks of dengue type 2 in north Queensland. Med J Aust 168: 221-225.

Hanna JN, Ritchie SA, Phillips DA, Serafin IL, Hills SL, van den Hurk AF, Pyke AT, McBride WJH, Amadio MG and Spark RL (2001). An epidemic of dengue 3 in far north Queensland, 1997-1999. Med J Aust 174:178-182.

Hare FE (1898). The 1897 epidemic of dengue in north Queensland. The Australasian Medical Gazette. 17: 98-107.

Montgomery BL and Ritchie SA (2002). Roof gutters: a key container for Aedes aegypti and Ochlerotatus notoscriptus (Diptera: Culicidae) in Australia. Am J Trop Med Hyg 67: 244-246.

Rapley LP, Johnson PH, Williams CW, Silcock RM, Larkman M, Long SA, Russell RC, Ritchie SA. 2009. A lethal ovitrap-based mass trapping scheme for dengue control in Australia: II: Impact on populations of the mosquito Aedes aegypti. Med Veterin Entomol 23: 303-316.

Ritchie SA (2005). Evolution of dengue control strategies in north Queensland, Australia. Arborvirus Research in Australia 9: 324- 330.

Ritchie SA, Hanna JN, Hills SA, Piispanen JP, McBride WJH, Pyke A, and Spark RL (2002). Dengue control in north Queensland, Australia: case recognition and selective indoor residual spraying. Dengue Bull 26: 7-13.

Ritchie SA, Long SA, Hart AJ, Webb CE, and Russell RC (2003). An adulticidal sticky ovitrap for sampling container-breeding mosquitoes. J Am Mosq Control Assoc 19:235-242.

Ritchie SA, Long S, Smith G, Pyke A, and Knox TB (2004). Entomological investigations in a focus of dengue transmission in Cairns, Queensland, Australia using the sticky ovitrap. J Med Entomol 41: 1-4.

Ritchie SA, Long SA, McCaffrey N, Key C, Lonergan G, Williams CR. 2008. A biodegradable lethal ovitrap for control of container-breeding Aedes. J. Amer. Mosquito Control Assoc. 24: 47-53.

Ritchie SA, Moore P, Carruthers M, Williams CR, Montgomery BL, Foley P, Ahboo S, van den Hurk, AF, Lindsay MD, Cooper R, Beebe N, Russell RC (2006). Discovery of a widespread infestation of Aedes albopictus in the Torres Strait, Australia. J Am Mosq Control Assoc. 22: 358-365.

Ritchie SA, Rapley LP, Williams CW, Johnson PH, Larkman M, Silcock RM, Long SA, Russell RC. 2009. A lethal ovitrap-based mass trapping scheme for dengue control in Australia: I. Public acceptability and performance of lethal ovitraps. Med Veterin Entomol 23: 295-302.

Tun-Lin.W, Kay, B.H and Barnes A. (1995). The premise condition index: A tool streamlining surveys of Aedes aegypti. Am.J.Trop.Med.Hyg, (1995) 53 (6): 591-594.

Zeichner BC and Perich MJ (1999). Laboratory testing of a lethal ovitrap for Aedes aegypti. Med Vet Entomol 13: 234-238.

References


Appendix 1: Specific dengue tests

Details Where performed

TEST: NS1 ELISA

This test detects the non-structural dengue virus protein NS1 in patient serum. The advantage of this test is that NS1 may be detectable in the blood of a dengue patient as early as Day 1 of onset and up to Day 9. As a result the test can detect dengue earlier than other serological tests which are based on the detection of dengue-specific IgM and IgG. In a primary infection the NS1 antigen can be detected several days before IgM develops and up to two weeks before IgG is present.

It may also detect viral protein after the period in which PCR may detect viral RNA, meaning it can bridge a possible gap in detection capability between PCR and IgM or IgG serology tests.

The test will detect NS1 antigen in patients infected with any of the four serotypes of dengue and is effective for diagnosis of both primary and secondary dengue infections.

The “BioRad” form of the ELISA reports 91% sensitivity and 100% specificity. Dengue NS1 results are reported on auslab as REACTIVE, Non-reactive or Equivocal.

Cairns and Townsville Base Hospitals

Sullivan and Nicolaides Pathology Brisbane

TEST: PCR

Dengue PCR test is a very specific test for dengue that is based on detection of actual virus RNA. The PCR is only useful during the first week of the illness (1-5 days following onset of symptoms) before rising IgM antibodies clear the virus from circulation. The sensitivity of the test can be affected by transport and storage conditions.

A ‘detected’ dengue PCR test is confirmation of a recent dengue virus infection. A ‘not detected’ result however, must be interpreted with caution and in conjunction with IgM results. Where clinical suspicion of dengue is high a second sample should be collected to look for rising IgM antibodies.

During an outbreak, PCR tests play an important part in the diagnosis of dengue. In 2003 approximately 50% of diagnoses were made through PCR tests.

QHFSS– Public Health Virology Laboratory Brisbane and Townsville Hospital

TEST: Dengue IgM & IgG EIA (presumptive result)

Once the dengue virus comes into contact with cells in the immune system, IgM antibodies are produced. Most typically IgM is reliably detectable 6 days after onset of symptoms but there have been reports of IgM appearing by day 1 and, in around 30-50% of patients, by day 3 post onset of illness. There is a greater risk of false negatives before day 6 (but these samples may be PCR positive).

In some cases IgM can persist for months or years following a dengue infection. Due to the long term persistence of IgM in some individuals a single reactive IgM test result alone is not conclusive. It is necessary to demonstrate a rising (or falling) antibody titre between paired acute and convalescent serum samples collected 10 to 14 days apart before a laboratory confirmation is obtained.

Both public hospitals and private pathology laboratories

Appendices

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Details Where performed

TEST: Dengue IgM & IgG EIA (presumptive result) continued

In some cases IgM can persist for months or years following a dengue infection. Due to the long term persistence of IgM in some individuals a single reactive IgM test result alone is not conclusive. It is necessary to demonstrate a rising (or falling) antibody titre between paired acute and convalescent serum samples collected 10 to 14 days apart before a laboratory confirmation is obtained.

In primary dengue infections IgG antibodies appear several days after the appearance of IgM and can persist for a lifetime. A single IgG reactive specimen in the absence of IgM is suggestive of a past infection.

In people with secondary dengue infections IgG will often be detectable at higher levels than IgM in an acute phase specimen. The IgG often precedes the appearance of IgM in secondary infections. Therefore if dengue IgM antibodies are not detected in a post day-3 sample in an acute illness, dengue IgG antibody levels should be determined.

These tests are designed for screening purposes. While the tests are highly sensitive they suffer to varying degrees from cross reactivity with other flaviviruses. Unless the test is undertaken on a sample collected during an outbreak, the tests do not constitute a confirmed case of dengue, particularly where a single serum sample is tested in isolation.

Commercially available tests for anti-dengue virus antibody (either IgG or IgM) are available from a number of companies and in a variety of formats including conventional EIA based formats and immunochromatographic rapid card type tests. Due to the variable specificity these tests display, in Queensland all samples that are reactive in a commercial test are referred to the QHFSS Public Health Virology Laboratory, Brisbane for confirmatory testing.

Laboratories will report these results as ‘presumptive’ and confirmatory testing will be done at QHFSS. Based on this presumptive test report alone, GPs may mistakenly report to patients that dengue has been confirmed.

TEST: Flavivirus IgM capture EIA

A flavivirus IgM screening test is performed on all referred reactive dengue IgM EIA specimens. The sample is screened using a pool of flaviviruses to detect specific anti-flavivirus IgM. The pooled flaviviruses are dengue serotypes 1 - 4, Japanese encephalitis, Kokoberra, Kunjin, Alfuy, Murray Valley encephalitis and Stratford viruses.

QHFSS Public Health Virology Laboratory, Brisbane

TEST: Flavivirus - specific IgM and IgG EIAs (confirmatory)

All equivocal or reactive flavivirus IgM capture EIA specimens are then further tested to determine the specific infecting flavivirus.


TEST: Haemagglutination inhibition test (HAI)

This test may identify the infecting flavivirus through measuring antibody titre levels to specific flaviviruses. A four fold rise or fall in titres is required. Due to the development of the flavivirus IgM capture and specific typing EIA this test is now used infrequently. It is still used occasionally, however, to confirm apparent secondary dengue infections.



Appendix 2: Example of test results and incorrect diagnoses of dengue

Example

A woman became unwell on 16 March 2004. She saw the GP on 18 March. Dengue serology was collected and the IgM results indicated NEGATIVE to dengue and the report stated: “Please repeat serology in approximately 14 days”.

Four days later (22 March), another blood sample was taken and IgM results indicated POSITIVE to the dengue virus.

The private laboratory notified TPHU of the woman’s positive IgM result on 26 March – 8 days after the GP had suspected dengue.

TPHU requested the specimen collected on 18 March to be forwarded to QHFSS for PCR testing, this specimen confirmed dengue.

By the time TPHU were notified of the preliminary IgM positive result on the 26 March, this woman had been viraemic for 10 days, consequently mosquito control intervention methods were delayed and several others in her block became infected with dengue.

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Appendix 3: Dengue case report form

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Appendix 4: Timeline of dengue 2 outbreaks, Cairns 2003-2004

Manunda, Cairns

2 11-14/02/03 onsets of Manunda cases x 3

2 21/02/03 date first Manunda notification

2 24/02/03 date DART first visit to Manunda

Parramatta Park, Cairns

2 05/03/03 date first suspicion about Parramatta Park

2 06/03/03 date Parramatta Park confirmation

2 06/03/03 date DART first visit to Parramatta Park

2 7 & 10/03/03 dates initial Parramatta Park media releases

2 25/02/03 onwards onset first recognised Parramatta Park cases

2 9-10/02/03 onset earlier Parramatta Park cases

‘Patient zero’ - PNG importation into Cairns

2 22/01/03 onset PNG importation

2 08/02/03 onset PNG case’s sister

2 12/03/03 confirmation PNG cases as dengue

2 14/03/03 discovery of backyard well

2 20/07/03 last recognised onset date

2 20/10/03 outbreak declared over (total = 459 cases)

Brown St, Cairns

2 26/10/03 first recognised onset

2 15/11/03 last recognised onset

2 15/01/04 outbreak declared over (total = 5 cases)

Edge Hill, Bentley Park, Bungalow, Manoora, Parramatta Park, Cairns

2 05/02/04 onset first Edge Hill case

2 06/02/04 onset Bentley Pk case

2 07/02/04 onset Westcourt case

2 09/02/04 onset first Bungalow case

2 09/02/04 onset first Edmonton case

2 17/02/04 next Edge Hill case

2 21 & 22/02/04 onsets 2 more Bungalow cases

2 23 & 25/02/04 onsets 2 more Edmonton cases

2 23/02/04 onset Manoora case

2 28/02/04 onset Park case

2 26/07/04 last onset date

2 26/10/04 outbreak declared over (total=79 cases)

2 (Street names are fictitious)


Appendix 5: Dengue Mosquito Surveillance Methods

Ovitraps Pro Con Settings/areas

Conventional Simple to operateSimple to post paddleCheap material Sensitive for low populations

Labour intensiveTime delay hatching etcExpertise to identifyCentral lab for raising adultsSample mortalityOvi positing adults not killed (exotic)Quarantine issues with transport Interference by animals

Suitable for remote areas due to ease of use sending sample

Sticky

2 Clippy Simple to operateCheaper to run compared to conventionalImmediate result

Expertise to identifyConstructionInterference by animals

Sheltered

2 Brazil Simple to operateAvailabilityImmediate result

Expertise to identifyQuestions of efficacyInterference by animals

Semi-sheltered

2 Lethal Kills adults – outbreakCheap

Expertise to identifyInsecticideRaise eggsModerate sensitivityNo real time idInterference by animals

Sheltered

Sentinel tyre/bucket

SensitiveCheapEasy to useCope with dry conditions

Expertise to identifyNot real timeCleaning and maintenanceRisk of missing incursionBulky

Dry conditionsLess regular checking

Larval collection

ImmediateDetermined breeding siteRepresentative coverage

Expertise to identifyTrained and skilled labour required for collectionRainfall dependantSample issues - transportAccess to cryptic, elevated and subterranean sites

Everywhere

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Ovitraps Pro Con Settings/areas

BG trap ImmediateSensitive Easy to usePublicly acceptedDoes not require CO2Portable

ExpensivePower/batteryExpertise to identifyDamaged specimensSecuritySupply

Protected area (from rain)

EVS trap ImmediateEasy to useOutdoor use

Need CO2Large number of mixed species, not efficient for Ae. aegyptiNot cheapBatteriesMaintenance

Anywhere outdoors/indoors

Backpack aspirators

Immediate resultTarget specific resting sites

IntrusiveNot as sensitive as BG trapHeavy to carryMosquito has to be present at same time as operatorTiming

Indoors


Appendix 6: Ovitraps

Sticky ovitraps

Sticky ovitraps are a new method to measure the relative abundance of egg-laying (gravid) female Ae. aegypti. The north Queensland design comprises two 1.2L black or red plastic buckets, clipped together (Fig. 1). The base of the top bucket is removed to provide access for the mosquitoes to enter the trap. The sides of the top bucket are fitted with a specific sticky adhesive (Atlantic Paste & Glue’s UVR-32 glue) panel. The bottom bucket is filled to the three quarter level with tap water into which a lucerne pellet is added to attract gravid mosquitoes. The addition of a Prolink (S-methoprene) pellet prevents the emergence of adult mosquitoes from any hatched eggs. The trap may collect other container-breeding mosquitoes such as Ae. notoscriptus, Ae. palmarum and Culex quinquefasciatus.

Sticky ovitraps can serve a variety of functions. This was best demonstrated during the 2003 dengue epidemic in Parramatta Park, an older suburb in Cairns. Traps set before, during and after epidemic transmission provided valuable information on the relative density of mosquitoes needed for epidemic transmission, the efficacy of control measures and virus activity in mosquitoes. A sticky ovitrap index (SOI), the mean number of female Ae. aegypti per sticky ovitrap (set for one week), is a useful statistic for measuring the potential risk of dengue transmission. Data from the Parramatta Park outbreak suggests that a SOI > 1 is a risk for dengue transmission; the SOI peaked at just under 4 when the epidemic started (Ritchie et al. 2004).

Sticky ovitraps along with lethal ovitraps (refer next section), are useful for gauging the risk of dengue transmission during dengue case interventions. The relative risk of dengue transmission following an initial intervention is a function of the proportion of mosquitoes collected by sticky ovitraps that are Ae. aegypti and the number of positive lethal ovitraps. In other words, if most of the mosquitoes collected in the sticky ovitraps are Ae. aegypti and the percentage of positive lethal ovitraps is high (>50%), then the risk of ongoing transmission is high. It is important to note that these values are subjective and no clear link between the SOI and actual dengue transmission has yet been established. Control measures should always be carried out despite a low SOI, although the area controlled may be modified at the direction of the medical entomologist.

Adult mosquitoes collected from sticky ovitraps can be tested for the presence of dengue virus (piloted in Cairns 2009).

Sticky ovitraps are used in Cairns to form a dengue mosquito surveillance network of approximately 70 traps set in volunteers’ yards. Each trap services two standard city blocks in those parts of the city that have a history of multiple recent dengue outbreaks, and where residents are at a higher risk of the severe health complications associated with multiple infections of dengue viruses. Traps are monitored each week, to determine where and when dengue mosquito populations are escalating, thereby indicating elevated

Fig 1: Sticky ovitrap – useful for monitoring gravid female Ae. aegypti. Adults trapped in Cairns are sent for PCR analysis to test for dengue-virus.

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risk. This data is used to target preventative inspections by Queensland Health and Cairns City Council to locate key containers or key premises that are breeding dengue mosquitoes. The DART have dispensed with the use of sticky ovitraps as a dengue case response tool, due to the logistical demand to service large numbers of these traps during widespread and/or prolonged outbreaks.

Lethal ovitraps

Since 2004 interior residual spraying by the DART has been largely replaced by the en masse deployment of lethal ovitraps (egg traps). These traps (Fig. 2a) are simply small, black, plastic buckets three quarters filled with tap water, with a lucerne pellet added and a velour strip treated with insecticide (less than 0.007g bifenthrin per strip). The low dose of insecticide ensures that the trap is safe to humans and pets. This method employs a “lure and kill” strategy; egg-bearing female mosquitoes are lured into the bucket by the water in search of a suitable site to lay eggs. These females are killed when they contact the strip while laying eggs. Typically 2-4 buckets per yard (refer Fig. 2b) are set for 4 weeks in most yards within a minimum 200 m radius of a single residence where a person suffering from dengue lives, works or has spent significant time while infective (max. 12 days of infection). Operational use of this strategy to combat dengue outbreaks in Cairns and the Torres Strait suggests that large scale, or annihilation, ovitrapping is effective (eg. lethal ovitraps and yard inspections on Thursday Island, reduced dengue mosquito populations by 92 %, and dengue transmission ceased).

Fig 2: (a) The lethal ovitrap. A black 1.2 L plastic bucket is filled with water and a lucerne pellet. The red strip has been pre-treated with residual insecticide (bifenthrin, at 7 mg per strip). Plastic mesh is provided as a barrier to minimise the likelihood of pets drinking the water.

(b) Map showing the en-masse deployment of traps (black dots) when TPHN responds to a single dengue case.


Lethal ovitraps provide a ‘green’ alternative to dengue mosquito control due to the minimal use of pesticides, minimal contact with non-target insects/animals/humans, and minimal chemical exposure of health workers to pesticides during dengue outbreaks. This strategy has proven to be a breakthrough, allowing the rapid treatment of areas without using large doses of insecticide. However, a weakness of the system is the impost on time and resources to retrieve large numbers of ovitraps before the pesticide wears off and they begin to breed mosquitoes.

The biodegradable lethal ovitrap (BLO) can be deployed rapidly, and does not require retrieval. The BLO (Fig. 3) is designed as a kill and compost mosquito trap. This “set it – and forget it” strategy will enable more areas to be serviced at a faster rate. The BLO is made of 30 % plastic and 70 % corn starch, and is produced by Plantic Technologies Ltd. (http://www.plantic.com.au/docs/Plantic_BLO_CaseStudy.pdf ).

Fig 3: The biodegradable lethal ovitrap (BLO).

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Appendix 7: How to calculate Ae. aegypti indices and risk assessment in the non-dengue zone

Three indices are used to evaluate the risk of Dengue transmission:

House index (HI) = % of premises infested with Ae. aegypti (L&P) expressed as a whole number;

Container index (CI) = % water holding containers infested with Ae. aegypti (L&P) expressed as a whole number;

Breteau index (BI) = number of positive containers per 100 premises.

How to calculate Ae. aegypti indices

Total number of premises checked 90Premises found with Ae. aegypti 30House index (HI) 30/90 x 100 = 33

Total wet containers 200Wet containers with Ae. aegypti 80Container index (CI) 80/200 x 100 = 40

Breteau index (BI) 80/90 x 100 = 88

Risk assessment based on WHO Density Figure (in scale of 1-9)*

WHO Density Figure House Index(HI)

Container Index(CI)

Breteau Index(BI)

1 1-3 1-2 1-4

2 4-7 3-5 5-9

3 8-17 6-9 10-19

4 18-28 10-14 20-34

5 29-37 15-20 35-49

6 38-49 21-27 50-74

7 50-59 28-31 75-99

8 60-76 32-40 100-199

9 77 41 200

*Developed for using in yellow fever control and later applied for Dengue control, WHO (1972)

Epidemiological Significance

Not at risk of disease transmission: Density figure <1; HI < 1; BI < 5.

At risk of disease transmission: Density figure > 1; HI > 1; BI > 5.

The higher the density figure the more significant risk of transmission.


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Appendix 9: How to calculate breeding site prevalence in the non-dengue zone

(Categorization based on Barker-Hudson et al (1988)

Daily Summary Sheet

Town: Date: No of premises inspected:

Categorising With larvae Without larvae Total

1: Garden accoutrements:Plant pots, plant pot saucers, bottles and vases for plants and flowers, container for striking plants cuttings, ornamental tyres, clam shells, bird baths, fountains, ornamental ponds.

2: Water storage containers:Rainwater tanks, wells, metal drums.

3: Discarded household items:Garden bins and upturned lids, washing machines, freezer cabinets, buckets, kitchen items (cups, glasses, jugs, bowls, dishes, trays etc.), toys.

4: Rubbish:Disposable plastic containers (for ice cream, margarine), tyres, drink cans, food containers, old drums.

5: Domestic-commercial usage containers:Copper boilers, concrete wash tubs, plastic and canvas tarpaulins, beer kegs, animal water dishes (dog bowls, bird baths).

6: Recreation items:Boats, canoes, swimming pools, kids pools.

7: Building fixture and materials:Storm water traps, gully traps, sumps, stored iron sheeting, pipe.

8: Natural habitats:Tree holes, bromeliads, and other plant axils, palm fronds.

GS1

0520

For more informationContact your Local Council or visit:

www.health.qld.gov.au/mozziediseases/default.asp

www.health.qld.gov.au/dengue/default.asp

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