disease eradication

Disease Eradication The Past The Present and The Future

By Dr Ehab OmraniM.B.B.Ch

M.P.H (Occupational Health) D.T.M&H(Tropical Medicine)

CONTENT

1. Definition

2. Eradication Criteria

3. Successful Eradication Programs

4. Ongoing Eradication Programs

5. Former Eradication Programs

Definition

EradicationIt is an absolute process an “ all or none”

phenomenon.

Restricted to termination of an infection from the whole world.

Definition

It is sometimes confused with:

1. Elimination: Which used to describe of eradication of disease

from a large geographic region or political jurisdiction

• When a disease stops circulating in a region, it’s considered eliminated in that region.

• If a particular disease is eliminated worldwide, it’s considered eradicated.

Definition

Polio, for example, was eliminated in the United States by 1979 after widespread vaccination efforts.

2. Further confusion arises from the use of the term eradication to refer to the total removal of a given pathogen from an individual (also known as clearance of an infection).

Eradication Criteria

Selection of infectious diseases for eradication is based on rigorous criteria?

Both biological and technical features determine whether a pathogenic organism can be (at least potentially) eradicated or not.


1. The targeted organism must not have a non-human reservoir.

This implies that sufficient information on the life cycle and transmission dynamics is available at the time an eradication initiative is programmed.

In the case of animal diseases, the infection reservoir must be an easily identifiable species, as in the case of rinderpest), and/or amplify in the environment.


2. An efficient and practical intervention (e.g., vaccine) must be available to interrupt transmission of the infective agent.

3. The disease to be eradicated should be clearly identifiable, and an accurate diagnostic tool should exist.


4. Economic considerations, as well as social and political support and commitment, are other crucial factors that determine eradication feasibility.

Eradication Programs

Two successful programs targeting 1. Smallpox

2. Rinderpest


Two former programs targeting

1. Hookworm

2. Yellow fever


Four ongoing programs targeting 1. Poliomyelitis

2. Yaws

3. Dracunculiasis

4. Malaria


Five more infectious diseases have been identified as of April 2008 as potentially eradicable with current technology:

1. Measles

2. Mumps

3. Rubella

4. Lymphatic filariasis

5. Cysticercosis

Successful Eradication Programs

Smallpox

Smallpox was the first disease, and so far the only infectious disease of humans, to be eradicated by deliberate intervention.

It became the first disease for which there was an effective vaccine in 1798 when Edward Jenner showed the protective effect of inoculation (vaccination) of humans with material from cowpox lesions

Smallpox

Eradication was accomplished with a combination of focused surveillance—quickly identifying new smallpox cases—and ring vaccination.

Smallpox

“Ring vaccination” meant that anyone who could have been exposed to a smallpox patient was tracked down and vaccinated as quickly as possible, effectively corralling the disease and preventing its further spread.

Smallpox

Last natural smallpox case was of Ali Maow Maalin in, Merca/ Somalia on October 26:1977

http://en.wikipedia.org/wiki/File:Smallpox.jpg

Smallpox

It is useful to consider the epidemiological factors which have led to eradication of smallpox; these could form the basis for eradication for other disease:

1. No known animal reservoir.

2. No long-term carrier of the virus.

3. Life-long immunity, after recovery from the disease.

4. Simple detection of cases , the rash was so characteristic and occurred in visible parts of the body.

Smallpox

5. Persons with subclinical infection did not transmit the disease

6. Vaccine highly effective, easily administered, heat stable, and confers long term protection

7. International cooperation

Rinderpest

• It is a viral disease which infected cattle and other ruminants and belonged to the same family as measles

• During the 20th century, there were a series of campaigns to eradicate it, through the use of a live attenuated vaccine

• The final, successful campaign was led by the Food and Agriculture Organization (FAO) of the United Nations.

RinderpestOn 14 October 2010, with no diagnoses for nine

years, the FAO announced that the disease had been completely eradicated.

It is the first (and so far the only) disease of livestock to have been eradicated by human undertakings.

Ongoing Eradication Programs

1-Dracunculiasis; guinea worm disease

It is a painful and disabling parasitic disease caused by a worm, Dracunculus medinensi.

It is spread through consumption of drinking water infested with copepods hosting the larvae.

Dracunculiasis; guinea worm disease

• Guinea worm disease is set to become the second human disease in history, after smallpox, to be eradicated.

• It will be the first parasitic disease to be eradicated and the first disease to be eradicated without the use of a vaccine or medicine.

Dracunculiasis

Eradication efforts have been based :

1. On making drinking water supplies safer (e.g. through treating the water with larvicide).

2. Containment of infection.

3. Education for safe drinking water practices.

Dracunculiasis

The original goal for eradication was 1995.

Two decades of eradication efforts have reduced guinea worm's global incidence to: more than 99.99% to 126 cases in 2014, down from an estimated 3.5 million in 1986

Dracunculiasis

South Sudan, the world's youngest nation, reported 70 cases or 56 percent of the worldwide case total in 2014.

The remaining indigenous cases in 2014 were reported in isolated areas of Chad (13), Mali (40), and Ethiopia (3).

2-Measles

It is an airborne disease

Spreads easily through the coughs and sneezes of those infected , and contact with saliva or nasal secretions.

Nine out of ten people who are not immune who share living space with an infected person will catch it.

Measles

The measles vaccine is effective at preventing the disease?

Vaccination has resulted in a 75% decrease in deaths from measles between 2000 and 2013 with about 85% of children globally being currently vaccinated.

Measles

In 2009 the regional committee for Africa agreed a goal of measles elimination by 2020

Europe had set a goal to eliminate measles transmission by 2010, but were hindered by:

• The MMR vaccine controversy ?• They have set a new target of 2015

MeaslesThe Americas set a goal in 1994 to eliminate measles

transmission by 2000, and successfully achieved regional measles elimination in 2002.

As of February 2015, measles is no longer eliminated in the US.

From January 1 to April 10, 2015, 159 people were reported to have measles.

most of these cases [117 cases (74%)] are part of a large, multi-state outbreak linked to an amusement park in California

Outbreak Response in Sudan

5 April 2015 – The Ministry of Health of Sudan, in collaboration with the World Health Organization (WHO), UNICEF and other partners, respond to the measles outbreak

More than 1600 suspected measles cases (with 710 confirmed) have been reported from 23 localities in 12 states of Sudan.

Outbreak Response in Sudan

One of the most affected states is West Darfur, with most cases being reported among goldmine workers

A WHO proposal to allocate US$ 3.9 million for response activities

Ongoing actions are being undertaken for the implementation of initial response and containment measures including:

1. Case management

2. Alert investigation

3. Response vaccination campaigns and community health awareness.

Geographic distribution of measles cases in the EMR countries by district and final diagnosis between July 2010 and June 2011

Source : Official countries’reports

Measles

At the 63rd World Health Assembly in May 2010, delegates agreed to move towards eradication, although no specific global target date has yet been agreed

Challenges

Funding: specially for the follow-up

campaigns

National managerial Capacity:– Inadequate number and qualification of

staff

Competing priorities:– Polio eradication

Pockets of susceptible populations/groups – Hard to reach populations in low income

countries– Pockets in countries with big expatriate

population

• Security situation: rapidly deteriorating in

the EMR– Delayed implementation of planned

activities

– Financial support from international partners

– Interest of the countries

– Polio infrastructures

Opportunities

Measles

History of polio…• The disease of poliomyelitis has a

long history.

• The first example may even have been more than 3000 years ago.

• An Egyptian stele dating from the 18th Egyptian dynasty shows a priest with a deformity of his leg characteristic of the flaccid paralysis typical of poliomyelitis.

3-Poliomyelitis (polio)

Poliomyelitis(polio)

• The World Health Assembly launched the Global Polio Eradication Initiative (GPEI) in 1988

• Since the GPEI was launched, the number of cases has fallen by over 99%.

• In 2013, only three countries in the world remain polio-endemic: Nigeria, Pakistan and Afghanistan

Poliomyelitis(polio)

Middle East:The most recent case reported from Syria had

onset of paralysis on 21 January 2014, while in Baghdad-Resafa province, on 7 April 2014.

Horn of AfricaThe most recent case, which had onset of

paralysis on 11 August 2014, was from central Somalia

The Global Polio Eradication Initiative(GPEI)

ObjectivesTo interrupt transmission of wild poliovirus as

soon as possibleTo achieve certification of global polio

eradicationTo contribute to health systems development

and strengthen routine immunization and surveillance for communicable diseases

The Global Polio Eradication Initiative

Four Pillars of the Global Polio Eradication

Initiative Strategy:

1. Routine Immunization.

2. Supplemental Immunization Activities.

3. Acute Flaccid Paralysis (AFP) Surveillance.

4. Targeted Mop-Up Campaigns.

1. Routine Immunization

• A major cornerstone of the polio eradication strategy

• According to WHO/UNICEF immunization coverage estimates, 86% of infants received three doses of oral polio vaccine in 2010, compared with 75% in 1990.

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Good routine OPV coverage:

1. Increases population immunity

2. Reduces the incidence of polio

3. Makes eradication feasible plan of routine immunization for out reach areas.



2. Supplemental Immunization Activities

• Mass polio immunization campaigns that complement routine immunization programs are intended to:

Interrupt transmission by immunizing every child under the age of 5 with oral polio vaccine annually, regardless of the number of times they have been immunized previously.


3. Acute Flaccid Paralysis (AFP) Surveillance• As many as 90% of people infected with the

poliovirus experience very mild or no symptoms.

• A single symptomatic case can therefore represent a significant community-wide outbreak.

• Robust surveillance to detect and investigate every case of polio-like AFP is essential to polio eradication.


4. Targeted Mop-Up Campaigns

Last stage in polio eradication

Low routine immunization coverage: very dense or mobile populations, inadequate sanitation, and poor access to health services exacerbate communities’ vulnerability to polio.


In focal areas where polio cases have been confirmed within the previous 3 years and circulating virus is confirmed or suspected.

In mop-up campaigns vaccinators go house-to-house to immunize every child under 5 and help to stop transmission.


Before a WHO region can be certified polio-free, the following conditions must be satisfied:

(A) AT LEAST THREE YEARS OF ZERO POLIO CASES DUE TO WILD POLIOVIRUS

(B) EXCELLENT CERTIFICATION STANDARD SURVEILLANCE

(C) EACH COUNTRY MUST ILLUSTRATE THE CAPACITY TO DETECT, REPORT AND RESPOND TO “IMPORTED” POLIO

CASES.

The goal of the 2013-2018 Polio Eradication and Endgame Strategic Plan is to complete the eradication and containment of all wild, vaccine-related and Sabin polioviruses, such that no child ever again suffers paralytic poliomyelitis

Poliomyelitis(polio) in Libya

Libya reported the last confirmed polio case in 1991.

Routine immunization• Routine immunization against polio has

been mandatory since 1970.

National immunization days• National immunization days and supplementary

immunization days in high-risk areas are conducted yearly.

Poliomyelitis(polio) in Libya

Acute flaccid paralysis surveillance• National reporting started in Libya in 1997. • Acute flaccid paralysis surveillance indicators have met

certification standards since 2002.

Laboratory• There is no poliovirus laboratory in Libya; it is served by the

Tunisian poliovirus regional reference laboratory in Tunisia. • laboratory containment of polioviruses has been completed

and a report documenting the quality of containment activities has been submitted to WHO.

Conclusion

• At present, polio is endemic in three countries

• Until poliovirus transmission is interrupted in these strongholds, all countries remain at risk, as shown not only by the outbreak in Syria, but also in recurrent outbreaks across sub-Saharan Africa, including an ongoing outbreak in Somalia.

• But the outbreak also serves as a reminder that high vaccination coverage is essential in countries where the disease is not currently circulating.

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Former Eradication Programs

HookwormHookworm infection is caused by the transmission

of the hookworm parasite common to warmer climates.

Hookworm larvae live in soil and typically enter humans through the soles of their feet

Hookworm eradication campaign start at US in 1909

Hookworm

700 million people worldwide, including 44 million pregnant women.

Tropical or sub-tropical environments in poverty-stricken areas of Africa, Latin America, Southeast Asia and China.

In North American countries, such as the United States, elimination of hookworm had been attained .

Hookworm

While regions such as Mexico still deal with these infections from parasitic worms, WHY?

Hookworm campaign start in the 1920s was supposed to focus on the eradication for those living in Mexico and other rural areas.

However, the campaign was politically influenced, causing it to be less successful.

Hookworm

In 2001, the World Health Organization adopted a resolution aimed at the deworming of 75 percent of all at-risk school-age children by 2010.

The largest public health program ever attempted to date.

Hookworm

A hookworm vaccine is also in development and is currently in a Phase I clinical trial by the Sabin PDP.

The 2012 WHO Road Map added 75% coverage of all at-risk pre-school-age children.

Conclusion

It is useful to consider the successful eradication programs, these programs could form the basis for eradication for other disease.

Both biological and technical features of the disease should be considered before starting it is eradication programme.

We have to put in our knowledge the economic , social and political issues before setting a specific global target date for any eradication programme.

THANK YOU

disease eradication

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