communicable diseases following natural disasters: a public health response stephen c. waring, dvm,...
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Communicable Diseases Following Natural Disasters:
A Public Health Response
Stephen C. Waring, DVM, PhDAssociate Director
Center for Public Health Preparedness
M Kokic, IFRC/RCSM Kokic, IFRC/RCS
Learning Objectives
To provide an overview of issues relevant to preparedness and response for emergency health relief workers
To understand the underlying factors favoring outbreaks of high morbidity communicable diseases
To review characteristics of diseases of greatest concern in disasters
Keys to minimizing morbidity and mortality
Adequate preparedness
Rapid, coordinated response
Sustained recovery
Communicable Diseases in Disasters
Timely coordinated intervention efforts require continual review and revision of preparedness missions at the local, national, and international level
Greatly facilitated by ongoing government, academic, and private organization training and education programs
Communicable Diseases in Disasters
Factors Favoring Disease Outbreak
rapid onset and broad impactcompromised sources of waterdisplacement of large numbers of peopletemporary sheltering in crowded conditionsinadequate sanitationcompromised waste management
Factors Favoring Disease Outbreak
potential food shortages
malnutrition/malnourishment
level of immunity
ongoing outbreaks prior to disastercompromised infrastructure
depleted supplies
susceptibility of population
Epidemiology and Surveillance
Must establish disease surveillance system as soon as possible
Identify key resourceslocal physicians, nurses, health workers
functioning hospitals/clinics
medical supplies immediately available
access to victimsroads, waterways, telecommunications, etc.
Epidemiology and Surveillance
Pre-impact epidemiologic informationbaseline (expected) frequencies and distributions of disease (incidence, prevalence, and mortality)
known risks
immunization coverage
awareness/education level in community
Epidemiology and Surveillance
Establish and distribute protocolslaboratory procedures
case definitions
case management
frequency and method of reporting
thresholds for every disease with epidemic potential above which a response must be initiated (epidemic threshold)
Epidemiology and Surveillance
Rapid health assessmentsconducted as soon as possiblepurpose - assess immediate impact/health needscritical to directing timely decisions and planningrely on pre-impact information
demographic, geographical, environmental, health facilities and services, transportation routes, security
information from key informantsvisual inspection of the affected area
Epidemiology and Surveillance
Rapid epidemiologic assessmentsplanned and completed as soon as possible following initial assessmentsbuilding on the information already acquiredprovide more detailed analysis of ongoing threats and facilitate monitoring of response and recoveryrequire additional resources and multiple skills and expertisea valuable tool that has been used in a number of post-disaster settings
Epidemiology and Surveillance
Surveillance and assessment systemsneed to be tailored to whatever means available if widespread disruption and displacement, information networks should include a variety of sources to be effectivecrucial to have the capacity to initiate field investigations immediately to verify potential outbreakslaboratory protocols, case definitions, and case management protocols must be agreed upon and distributed to all catchment areas
Epidemiology and Surveillance
Frequency and method of reportingusually telephone alert systemestablished as a matter of protocol at the outsetshould have necessary resources and personnel in place to ensure effective monitoringestablishment of thresholds for every disease with epidemic potential above which a response must be initiated (epidemic threshold) should be established
Epidemiology and Surveillance
Challenges in implementationmust be understood and communicated to ensure effort will meet expectations
considerations for planning/implementation
compromises between what is collected and how it is to be analyzed
competing priorities for same information
limitations of resources
lack of available information required to produce meaningful estimates
lack of standardization of collection/reporting protocols
Water-borne Diseases - Diarrhea
Diarrhea can be a major contributor to overall morbidity and mortality in a disaster due to:
large scale disruption of infrastructure
compromised water quality
poor sanitation
massive displacement of population into temporary crowded shelters
common sources of food and water subject to cross contamination
Water-borne Diseases - Diarrhea
Choleraspreads rapidly; high mortality across all age groupsmajor global threat and epidemic threat is constant in developing countries throughout the yearrapid recognition and response imperative during acute post-disaster phase to prevent epidemicemergence of antibiotic-resistant strains of Vibrio cholera complicate efforts in some regions and should be considered in preparedness planning
Water-borne Diseases - Diarrhea
DysenteryBacillary dysentery caused by ShigellaFecal-oral transmission from contaminated food/waterSuspect if bloody diarrhea presentparticular concern (along with cholera) due to ease of transmission, rapid spread in crowded conditions, and immediate life-threatening conditionsguidelines on managing outbreak available from WHO (http://w3.whosea.org)
Acute Respiratory Infections
Increased risk for pneumonia:overcrowdingsusceptibilitymalnourishmentpoor ventilation in temporary shelters
Many acute infections involve upper respiratory system; mild and self-limitingLower respiratory infections (bronchitis, pneumonia) are generally more severe and require hospitalization
Acute Respiratory Infections
Account for up to 20% of all deaths in children less than 5 years of age, with majority due to pneumonia (WHO)May account for a major portion of overall morbidity depending on:
Region affectedCharacteristics of displaced population and temporary dwellings
Early recognition and management are keys to avoiding an outbreak
Measles
Few outbreaks associated with natural disasters although possibility remains high
Outbreaks prevented througheffective early warning system
rapid response to suspicious reports
availability of vaccine
Measles
Mt Pinatubo eruption (Philippines) 1991measles accounted for 25% morbidity and 22% of mortality among 100,000 people displaced
attributed to very low immunization coverage and cultural barriers of indigenous tribe that represented majority of displaced population
Therefore, threat of measles epidemic remains high following natural disasters
Tetanus
Due to collapsing structures and falling debris
Earthquakes and tsunamis inflicts numerous crash injuries, fractures, and serious wounds
Tetanus expected when immunization coverage is low or non-existent
Injured and non-immunized should receive:prompt surgical and medical care of contaminated open wound
tetanus immunization and/or immunoglobulin depending on vaccination history and seriousness of the wound infection
Vector-Borne Diseases
Risk usually higher following disasters (hurricane [typhoon] flood, or tsunami)
Higher risk due to increase in number and range of vector habitats
Initially flushed out mosquito breeding sites return shortly after waters begin to recede
Vector-Borne Diseases
Factors favoring outbreaks:changing dynamics of vector
displacement of large numbers of people in temporary crowded shelters
Lag time of up to 8 weeks before onset
Vector-Borne Diseases: Malaria
associated with serious public health emergencies with little warning
likelihood of epidemic high when:disaster in malaria-endemic area
public health infrastructure is disrupted
highly vulnerable population exists
usually 4-8 weeks after initial impact
several weeks duration before peak
Vector-Borne Diseases: Malaria
Effective control possible in early stages if timely response in implementing control measuresMorbidity and mortality reduced with early diagnosis and treatment
If diagnosis delayed, treatment based solely on clinical history without demonstration of parasites
important considerations for planningemergence of anti-malarial resistanceincreased transmission potential due to expanding range of vector habitats
Vector-Borne Diseases: Malaria
vectors exclusively Anopheles - breed in stagnant fresh or brackish water
transmission efficiency dependent onspecies of mosquito
preferred breeding habits
prevalence of parasite
in endemic areas disruptions may change otherwise poor breeding conditions into favorable ones
Vector-Borne Diseases - Dengue
spreads rapidly, affects large numbersDengue hemorrhagic fever (DHF) associated with high mortality (particularly children)dramatic increase in incidence over past 20 years (100 million cases annually)endemic throughout all tropical regions
Vector-Borne Diseases: Dengue
transmitted by Aedes mosquitoes, primarily Ae. aegypti.
vector particularly suited for an urban cycle of transmission
breeds primarily in containers and other sources of standing water
breeds in and around human dwellings rather than groundwater pools and swamps
Vector-Borne Diseases: Dengue
Outbreaks contained only through early-warning and rapid response
Effective vector control critical but challenging due to:
availability of adequate resources
appropriate access to breeding habitats
Water-borne Diseases: Summary
DiseaseDisease Clinical FeaturesClinical Features Incubation Incubation PeriodPeriod DiagnosisDiagnosis TreatmentTreatment
Cholera profuse watery diarrhea, vomiting
2 hrs – 5 days direct microscopic observation of V. cholerae in stool
rehydration therapy; antimicrobials
Leptospirosis sudden onset fever, headache, chills, vomiting, severe myalgia
2 - 28 days Leptospira-specific IgM serological assay
penicillin, amoxi, doxyxycline, erythromycin, cephalosporins
Hepatitis jaundice, abdominal pain, nausea, diarrhea, fever, fatigue and loss of appetite
15 - 50 days Serological assay detecting anti-HAV of anti-HEV IgM antibodies
supportive care; hospitalize/ barrier nursing for severe cases; monitoring of pregnant women
Bacillary Dysentery
malaise, fever, vomiting, blood and mucous in stool
12 - 96 hrs Suspect if bloody diarrhea; confirm by isolation of organism
nalidixic acid, ampicillin; hospitalize seriously ill or malnourished; rehydration
Typhoid fever sustained fever, headache, constipation
3 - 14 days culture from blood, bone marrow, bowel fluids; rapid antibody tests
ampicillin, trimethoprim-sulfamethoxazole, ciprofloxacin
Vector-borne Diseases: Summary
DiseaseDisease Clinical FeaturesClinical Features Incubation Incubation PeriodPeriod DiagnosisDiagnosis TreatmentTreatment
Malaria fever, chills, sweats, head and body aches, nausea and vomiting
7 - 30 days parasites on blood smear observed using a microscope; rapid diagnostic assays if available
chloroquine, sulfadoxine-
pyrimethamine
Dengue Sudden onset severe flu-like illness, high fever, severe headache, pain behind the eyes, and
rash
4 - 7 days Serum antibody testing with ELISA or rapid dot-blot technique
intensive supportive therapy
Japanese encephalitis
quick onset, headache, high fever, neck stiffness, stupor, disorientation, tremors
5 - 15 days serological assay for JE virus IgM specific antibodies in CSF or blood (acute phase)
intensive supportive therapy
Yellow fever fever, backache, headache, nausea, vomiting; toxic phase-jaundice, abdominal
pain, kidney failure
3 - 6 days serological assay for yellow fever virus antibodies
intensive supportive therapy
Direct Contact Diseases: Summary
DiseaseDisease Clinical FeaturesClinical Features Incubation Incubation PeriodPeriod DiagnosisDiagnosis TreatmentTreatment
Pneumonia cough, difficulty breathing, fast breathing, chest indrawing
1 - 3 days Clinical presentation; culture respiratory secretions
co-trimoxazole, chloramphenicol, ampicillin,
Measles rash, high fever, cough, runny nose, red and watery eyes; serious post measles complications (5-10% of cases) - diarrhea, pneumonia, croup
10 - 12 days generally made by clinical observation
Supportive care; nutrition/hydration; vitamin A; control fever; antibiotics in complicated cases
Bacterial Meningitis
Sudden onset fever, rash, neck stiffness; altered consciousness; bulging fontanelle in <1 yrs of age
5 - 15 days Examination of CSF – elevated WCC, protein; gram negative diplococci
Penicillin, ampicillin, chloramphenicol, ceftriaxone, cefotaxime, co-trimoxazole; diazepam (seizures )
Tetanus difficulty swallowing, lockjaw, muscle rigidity,
spasms
3 - 21 days entirely clinical immune globulin
Summary
Immediate concern is rapid detection and response to address existing health needs and prevent epidemics
Factors that also play key roles in controlling communicable diseases in disaster setting:
Proper placement of sheltersProper placement of shelters VaccinationsVaccinations
Adequate sanitationAdequate sanitation Provision of clean waterProvision of clean water
Adequate personal hygieneAdequate personal hygiene Adequate nutritionAdequate nutrition
Vector controlVector control Health educationHealth education
Summary
Emergency response aimed to mitigate adverse health effects requires:
Multidisciplinary approach employing a broad range of expertiseIdentification and attention to those in need of immediate threat
Multidisciplinary effort forms framework for recoveryRequires ongoing preparedness planning, education, and training efforts
Closing Comments
Resilience of the local people is a key asset in recovering from all adversities – physical, social, and economic
Efforts should be made to strengthen community resilience in order to ensure a better future for those affected
Goal: Goal: Translate lessons learned into better Translate lessons learned into better preparedness, response, and recovery for the preparedness, response, and recovery for the next disaster certain to follow.next disaster certain to follow.
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flood--United States, 1993. MMWR 1994;43:481-4832. CDC. Surveillance in evacuation camps after the eruption of Mt.
Pinatubo, Philippines. MMWR 1992;41:9-123. Connolly MA, Gayer M, Ryan MJ, Salama P, Spiegel P, Heymann DL.
Communicable diseases in complex emergencies: impact and challenges. Lancet 2004:1974-1983
4. Connolly MA. Communicable disease control in emergencies: A field manual. Geneva: WHO, 2005.
5. Noji EK. The public health consequences of disasters. Prehospital & Disaster Medicine 2000;15:147-157
6. Toole MJ. Communicable Diseases and Disease Control In: Noji E, ed. The Public Health Consequences of Disasters. New York: Oxford University Press, 1997;79-100
7. World Health Organization. Tsunamis: Technical Hazard Sheet and Natural Disaster Profile: WHO, 2005.
8. Waring SC, Brown BJ. The threat of communicable diseases following natural disasters, a Public Health Response, Disaster Manage Response 2005;3(2):4-12.