Communicable Diseases Following Natural Disasters: A Public Health Response Stephen C. Waring, DVM, PhD Associate Director Center for Public Health Preparedness.

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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