“NATURAL DISASTERS-
A MICROBE’S PARADISE“
- Andrea J. Linscott
(Clinical Microbiology News Letter 29(8) April 2007)
Natural Disaster
DroughtEarthquakes
Hurricanes
TsunamiTornados
Flooding
Transmission of infectious agents
Impact phase (0-4 days)
Extrication, Immediate soft tissue infection
Post impact phase (4 d – 4 w)
Air- borne Disease Food -borne disease
Water -borne disease Vector- borne disease
Recovery phase (After 4 weeks)Those with long incubation(Leptospirosis , Leishmaniasis)
Most common causes of death in a disaster
• Diarrhea
• Acute respiratory infection
• Measles
• Malaria
• Malnutrition
- WHO
Factors that facilitate the spread of Microorganisms during a natural disaster
• Disruption of public water & sewage system
• Crowded living conditions
• Air borne transmission
•Lack of immunization
• Injury – related infection due to exposure to some debris
Communicable diseases with epidemic potential in natural disasters
Waterborne Transmission Incubation period
Cholera Fecal/oral, 2h-5d
Lepto-spirosis contaminated water 2-28d
Hepatitis or food 15-50d
Bacillary dysentery 12-96h
Typhoid fever 3-14d
Acute respiratory
Pneumonia Person to person by 1-3d
airborne respiratory
droplets
Direct contact
Measles Person to person by 10-12d
airborne respiratory
droplets
Bacterial
Meningitis 2-10d
Vector-borne
Malaria Mosquito 7-30d
Dengue fever Mosquito 4-7d
Japanese encephalitis Mosquito 5-15d
Yellow fever Mosquito 3-6d
Diagnosis
• Direct microscopic observation of V cholerae in stool
• Leptospira-specific IgM serologic assay
• Serologic assay detecting anti-HAV of anti-HEV IgM antibodies
• Suspect if bloody diarrhea; confirmation requires isolation of organism from stool
• Culture from blood, bone marrow,bowel fluids; rapid antibody tests- Salmonella typhi
•Clinical presentation; culture respiratory secretions-Streptococcuspneumoniae, Haemophilus influenzae,
•Generally made by clinical observation-Measles
•Examination of CSF - Meningitis
Vector-borne
• Parasites on blood smear,rapid diagnostic methods
• Serum antibody testing with ELISA or rapid dot-blot technique-Dengue
• Serologic assay for JE virus IgM specific antibodies in CSF or blood
• Serological assay for yellow fever virus antibodies
Northridge Earthquake 1994.
An unusual outbreak of coccidiomycosis
occurred
•The infectious fungal spores of Coccidioides immitiswere dispersed via large dust clouds generated by landslides triggered by the earthquake.
•C.immitis peaked 2 weeks after the earthquake
Flooding
Accounts for 40% of all natural disasters
Communicable disease transmitted during the flooding
Water borne diseases Vector borne diseases
• Typhoid fever Malaria
• Cholera Yellow fever
• Leptospirosis Water Nile fever
• Hepatitis A Dengue
• Diarrheal diseases after flooding and related displacement.
• Outbreak of diarrheal diseases after flooding in Bangladesh in 2004 involved > 17,000 cases of V.Cholerae and E.Coli infections.
• In a large study in Indonesia in 1992-1993 – S. enterica
paratyphi (paratyphoid fever) predominant
• Risk of diarrheal diseases outbreaks following natural disaster
is higher in developing countries than in industrialised countries.
• Dominican republic-Hurricanes David
and Fredrick, August 31 and Sep 5 ,1979
Marked increase in Typhoid,gastroenteritis,Measles,viral-hepatitis-measured 6 months after the Hurricane
• Over 75,000 cases of Plasmodium falciparum malaria associated with hurricane Flora (haiti) 1966
• Following hurricane Katrina (2005) several types of infections were seen
• V.Cholerae were confirmed among Katrina evacuees.
• No disease causing E.coli (CDC report)
Tsunamis
• Infections associated with tidal wave include traumatic wound infections
• Aspiration pneumonia due to inhalation of soil contaminated salt water
•Wound infections among survivors were polymicrobic-641 organisms were identified
• Most prominent-Aeromonas species, E.coli ,Klebsiella pneumoniae & Psudomonas aeruginosa
• Some of these organisms were resistant to all licensed antibiotics
• Bacteriological Analysis of water samples from Tsunami hit coastal areas of Kanyakumari District, TamilNadu
• 151 drinking water sources collected from tsunami-affected villages and relief shelters
• 37 % of the water samples were contaminated.
•No reports of acute diarrheal diseases or typhoid during the post-tsunami period
A report by the Department of Microbiology,University of Madras
P.Rajenndran et al,Indian Journal of Medical Microbiology(2006) 24 (2):114
• Relationship between natural disasters and communicable diseases – frequently misconstrued
• Fear derived from an association between large no of dead bodies and epidemics
Primary risk factors
• Population displacement.
• Availability of safe water and sanitation facilities.
• Degree of crowding.
• Health status of population.
• Availability of health care
services.
• Deaths from communicable diseases after natural disaster are less common.
• Outbreaks after flooding are better documented than those after earthquakes,volcanic eruptions and tsunamis
• Natural disasters that do not result in population displacement are rarely associated with outbreaks
A pathogen can be transmitted only if it is present in the environment where the natural disaster occurred
Communicable Disease Transmission – Risk assessment
An accurate communicable disease risk assessment is required
Identify
• Epidemic & endemic disease that are common in the affected area.
• Living conditions of the affected population.
• Availability of safe water and adequate sanitation facilities.
• Nutritional status and immunization coverage.
• Degree of access to healthcare.
Prevention /Control
• Hand washing,proper handling of water/food and sewage disposal, Oral rehydration therapy
(Improved Oral Rehydration salts for ORT)
• Avoid entering contaminated water
• Hepatitis vaccine
• Isolation , proper nutrition-If cause is Streptococcus-polyvalent vaccine (pneumonia)
• Rapid mass vaccination within 72h of initial case report,Vitamin A in children 6 mo to 5 yrs to prevent complications and reduce mortality (Measles)
Rapid mass vaccination-meningitis
Mosquito control, insecticide-treated nets,bedding,clothing
-malaria
Mosquito control,isolation of cases,mass vaccination-
Dengue , Japanese encephalitis,Yellow fever
•Rapid detection of the infectious agent is essential
•Development of novel diagnostic kits for rapid
detection of Shigella and E.coli species
-Department of Biochemistry,University of Madras
•Antibiotic treatment and vaccination for Shigella
species and other enteropathogens are not always
successful because they are increasingly resistant to
antibiotics and possess high antigenic variations.
•We have designed a rapid diagnostic kit and
alternative therapeutic strategies
Preventive Health Measures against the transmission
of infectious agents related to natural disasters
Key points listed by WHO
• Keep hands and vessels clean
• Avoid preparing food directly in areas surrounded by
flood water.
• Separate raw and cooked food.Cook food thoroughly
• Keep food at safe temperatures
• Use safe water
• Appropriate protective clothing to be worn during
rescue and clean-up operations
• Immunization