CHAPTER 1, FOOD SAFETY
A-3 INVESTIGATING FOODBORNE DISEASE OUTBREAKS
a. A foodborne-disease outbreak (FBDO) is defined as an incident in
which two or more persons experience a similar illness resulting from the
ingestion of a common food and epidemiological analysis implicates the food
as the source of the illness. Foodborne disease outbreaks include a single
case of illness such as one person ill from botulism or chemical poisoning.
b. In the event of a suspected foodborne outbreak, prompt action must
be taken to identify cases associated with the outbreak, identify
implicated food or beverage items, determine the factor or combination of
factors which permitted the outbreak to occur and initiate measures to
control or contain the spread of infection. Early identification of the
causative agent allows for specific treatment of patients. Additional cases
can be prevented by halting service or sale of an implicated food item.
Future outbreaks can be prevented by modifying or correcting procedures for
acquiring, processing and handling the implicated food. Assistance with
any investigation may be obtained from the nearest Occupational
Health/Preventive Medicine Department at a Naval Hospital or Clinic or
NAVENPVNTMEDU by telephone or message request. Procedures to Investigate
Foodborne Illness, a publication of the International Association of Milk,
Food and Environmental Sanitarians, Inc., P.O. Box 702, Ames, Iowa 50010,
provides excellent guidelines for conducting an investigation.
c. Outbreak Investigation Procedures. An outbreak investigation is
composed of several parts, many of which must be performed promptly and
simultaneously by the person or persons conducting the investigation.
Ideally, procedures, materials, personnel and responsibilities for
initiating and conducting an investigation would have been developed in
(1) Verify that there is an epidemic or outbreak. When suspected
cases of foodborne illness are reported, the first step involves verifying
whether an outbreak actually exists.
(2) Complete case history questionnaires.
(a) A case history questionnaire must be completed for each ill
Figure 1-9 provides an example.
(b) A questionnaire should also be completed for any person who
has not been ill, but who may have been exposed to the suspect food item,
meal, or facility. These "controls" can include family members, roommates,
coworkers, shipmates, and any others at risk who remained well.
Comparisons of ill and well
persons (e.g., food-specific attack rates) are used to analyze factors
contributing to the outbreak.
(c) Valid case history questionnaires collect information