Communicable Diseases Following Natural Disasters: A Public Health Response - PowerPoint PPT Presentation

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Communicable Diseases Following Natural Disasters: A Public Health Response


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Title: Communicable Diseases Following Natural Disasters: A Public Health Response

Communicable Diseases Following Natural
DisastersA Public Health Response
  • Stephen C. Waring, DVM, PhD
  • Associate Director
  • Center for Public Health Preparedness

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

Communicable Diseases in Disasters
  • Keys to minimizing morbidity and
  • 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

Factors Favoring Disease Outbreak
  • rapid onset and broad impact
  • compromised sources of water
  • displacement of large numbers of people
  • temporary sheltering in crowded conditions
  • inadequate sanitation
  • compromised waste management

Factors Favoring Disease Outbreak
  • potential food shortages
  • malnutrition/malnourishment
  • level of immunity
  • ongoing outbreaks prior to disaster
  • compromised infrastructure
  • depleted supplies
  • susceptibility of population

Epidemiology and Surveillance
  • Must establish disease surveillance system as
    soon as possible
  • Identify key resources
  • local physicians, nurses, health workers
  • functioning hospitals/clinics
  • medical supplies immediately available
  • access to victims
  • roads, waterways, telecommunications, etc.

Epidemiology and Surveillance
  • Pre-impact epidemiologic information
  • baseline (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 protocols
  • laboratory 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 assessments
  • conducted as soon as possible
  • purpose - assess immediate impact/health needs
  • critical to directing timely decisions and
  • rely on pre-impact information
  • demographic, geographical, environmental, health
    facilities and services, transportation routes,
  • information from key informants
  • visual inspection of the affected area

Epidemiology and Surveillance
  • Rapid epidemiologic assessments
  • planned and completed as soon as possible
    following initial assessments
  • building on the information already acquired
  • provide more detailed analysis of ongoing threats
    and facilitate monitoring of response and
  • require additional resources and multiple skills
    and expertise
  • a valuable tool that has been used in a number of
    post-disaster settings

Epidemiology and Surveillance
  • Surveillance and assessment systems
  • need to be tailored to whatever means available
  • if widespread disruption and displacement,
    information networks should include a variety of
    sources to be effective
  • crucial to have the capacity to initiate field
    investigations immediately to verify potential
  • laboratory protocols, case definitions, and case
    management protocols must be agreed upon and
    distributed to all catchment areas

Epidemiology and Surveillance
  • Frequency and method of reporting
  • usually telephone alert system
  • established as a matter of protocol at the outset
  • should have necessary resources and personnel in
    place to ensure effective monitoring
  • establishment of thresholds for every disease
    with epidemic potential above which a response
    must be initiated (epidemic threshold) should be

Epidemiology and Surveillance
  • Challenges in implementation
  • must 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

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

Water-borne Diseases - Diarrhea
  • Cholera
  • spreads rapidly high mortality across all age
  • major global threat and epidemic threat is
    constant in developing countries throughout the
  • rapid recognition and response imperative during
    acute post-disaster phase to prevent epidemic
  • emergence of antibiotic-resistant strains of
    Vibrio cholera complicate efforts in some regions
    and should be considered in preparedness planning

Water-borne Diseases - Diarrhea
  • Dysentery
  • Bacillary dysentery caused by Shigella
  • Fecal-oral transmission from contaminated
  • Suspect if bloody diarrhea present
  • particular concern (along with cholera) due to
    ease of transmission, rapid spread in crowded
    conditions, and immediate life-threatening
  • guidelines on managing outbreak available from

Acute Respiratory Infections
  • Increased risk for pneumonia
  • overcrowding
  • susceptibility
  • malnourishment
  • poor ventilation in temporary shelters
  • Many acute infections involve upper respiratory
    system mild and self-limiting
  • Lower respiratory infections (bronchitis,
    pneumonia) are generally more severe and require

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 affected
  • Characteristics of displaced population and
    temporary dwellings
  • Early recognition and management are keys to
    avoiding an outbreak

  • Few outbreaks associated with natural disasters
    although possibility remains high
  • Outbreaks prevented through
  • effective early warning system
  • rapid response to suspicious reports
  • availability of vaccine

  • Mt Pinatubo eruption (Philippines) 1991
  • measles 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

  • 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 measures
  • Morbidity and mortality reduced with early
    diagnosis and treatment
  • If diagnosis delayed, treatment based solely on
    clinical history without demonstration of
  • important considerations for planning
  • emergence of anti-malarial resistance
  • increased 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 on
  • species 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 numbers
  • Dengue 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.
  • vector particularly suited for an urban cycle of
  • 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
Disease Clinical Features Incubation Period Diagnosis Treatment
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
Disease Clinical Features Incubation Period Diagnosis Treatment
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
Disease Clinical Features Incubation Period Diagnosis Treatment
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 lt1 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
  • Immediate concern is rapid detection and response
    to address existing health needs and prevent
  • Factors that also play key roles in controlling
    communicable diseases in disaster setting

Proper placement of shelters Vaccinations
Adequate sanitation Provision of clean water
Adequate personal hygiene Adequate nutrition
Vector control Health education
  • Emergency response aimed to mitigate adverse
    health effects requires
  • Multidisciplinary approach employing a broad
    range of expertise
  • Identification and attention to those in need of
    immediate threat
  • Multidisciplinary effort forms framework for
  • Requires 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 Translate lessons learned into better
preparedness, response, and recovery for the next
disaster certain to follow.
  1. CDC. Rapid assessment of vectorborne diseases
    during the Midwest flood--United States, 1993.
    MMWR 199443481-483
  2. CDC. Surveillance in evacuation camps after the
    eruption of Mt. Pinatubo, Philippines. MMWR
  3. Connolly MA, Gayer M, Ryan MJ, Salama P, Spiegel
    P, Heymann DL. Communicable diseases in complex
    emergencies impact and challenges. Lancet
  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
  6. Toole MJ. Communicable Diseases and Disease
    Control In Noji E, ed. The Public Health
    Consequences of Disasters. New York Oxford
    University Press, 199779-100
  7. World Health Organization. Tsunamis Technical
    Hazard Sheet and Natural Disaster Profile WHO,
  8. Waring SC, Brown BJ. The threat of communicable
    diseases following natural disasters, a Public
    Health Response, Disaster Manage Response
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