Current Trends Flood Disasters and Immunization --
California
The heavy rains and floods in many areas of California this
year
have disrupted some community water supplies and sewerage systems.
Such natural disasters often result in public concern about
possible
contagion from flood waters due to contamination by sewage or
animal
carcasses.
Studies of flood and earthquake disasters have shown that
communicable disease outbreaks rarely result from such events (1).
Nevertheless, there is often a public demand for emergency mass
immunization, especially against typhoid fever, despite the fact
that
epidemic typhoid has been conspicuously absent following natural
disasters in the United States (where typhoid incidence is low) and
in
developing countries (where typhoid is endemic). Additionally, it
takes several weeks for typhoid antibodies to develop, and even
then,
immunization provides only moderate protection against the disease.
Also, adverse vaccine reactions are common (fever, headache,
malaise,
swelling and pain at the injection site) and burden flood victims
and
relief workers with more stress. Mass tetanus immunization
programs
are also not indicated, as floods pose no additional risk of
tetanus.
Management of flood-associated wounds should include appropriate
evaluation of tetanus immunity (and immunization if indicated) as
at
any other time.
Of greatest importance in preventing enteric disease
transmission
when water and sewerage systems have been compromised is to assure
that water and food supplies are safe to consume. When water
contamination has occurred or is suspected (e.g., drop in water
pressure, discoloration, turbidity, or unusual odors) only water
bottled or trucked from a safe source, water brought to a vigorous
boil, or water appropriately disinfected* should be consumed until
health authorities indicate that public supplies are again safe to
drink. Questions about the safety of foods exposed to flood waters
or
potentially spoiled due to interrupted refrigeration can be
directed
to local public health sanitarians.
Flood victims and relief workers should always wash their hands
with soap and water (boiled or disinfected when no regular safe
supply
is available) before preparing or eating food, after toilet use,
and
after participating in flood cleanup or handling potentially
contaminated articles.
While communicable disease outbreaks in the United States are
rare
after flooding, some potential does exist for waterborne disease
transmission (e.g., enterotoxigenic Escherichia coli, Shigella,
Salmonella, hepatitis A, Norwalk virus agents, and even such
infections as leptospirosis and tularemia); therefore,
flood-affected
communities should be under close surveillance.
Mass immunization programs at the time of natural disasters are
counterproductive and divert limited manpower and resources from
other
relief tasks. Such immunization programs may also give the public
a
false sense of security, leading to neglect of the basic rules of
hygiene and sanitation that are far more important than
immunizations
in preventing infectious diseases that flood waters may spread.
Reported in California Morbidity, March 11, 1983 (9).
Reference
Western KA. Epidemiologic surveillance after natural disaster.
Washington, DC: PAHO/WHO, 1982 (Scientific publication no.
420).
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