Communicable Diseases Following Natural Disasters: A Public Health Response Stephen C. Waring, DVM, PhD Associate Director Center for Public Health Preparedness.
Download ReportTranscript 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, PhD Associate Director Center for Public Health Preparedness M 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 Communicable Diseases 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 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 planning rely on pre-impact information demographic, geographical, environmental, health facilities and services, transportation routes, security 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 recovery 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 outbreaks 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 established 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 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 Cholera spreads rapidly; high mortality across all age groups major global threat and epidemic threat is constant in developing countries throughout the year 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 food/water Suspect if bloody diarrhea present particular concern (along with cholera) due to ease of transmission, rapid spread in crowded conditions, and immediate life-threatening conditions guidelines on managing outbreak available from WHO (http://w3.whosea.org) Acute Respiratory Infections Increased risk for pneumonia: overcrowding susceptibility malnourishment poor ventilation in temporary shelters Many acute infections involve upper respiratory system; mild and selflimiting Lower 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 affected Characteristics 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 through effective early warning system rapid response to suspicious reports availability of vaccine Measles 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 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 measures Morbidity and mortality reduced with early diagnosis and treatment If diagnosis delayed, treatment based solely on clinical history without demonstration of parasites 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. 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 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 Leptospiraspecific 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, trimethoprimsulfamethoxazole, 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, sulfadoxinepyrimethamine Dengue Sudden onset severe flulike 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 phasejaundice, abdominal pain, kidney failure 3 - 6 days serological assay for yellow fever virus antibodies intensive supportive therapy Direct Contact Diseases: Summary Incubation Period Disease Clinical Features 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 <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 shelters Vaccinations Adequate sanitation Provision of clean water Adequate personal hygiene Vector control Adequate nutrition Health education Summary 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 recovery 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. References 1. CDC. Rapid assessment of vectorborne diseases during the Midwest flood--United States, 1993. MMWR 1994;43:481-483 2. CDC. Surveillance in evacuation camps after the eruption of Mt. Pinatubo, Philippines. MMWR 1992;41:9-12 3. 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.