Food outbreak and foodborne illness Flashcards
food outbreak investigation steps
- define outbreak and confirm existence
define numerator (cases of illness) and denominator
determine if disease rates are beyond expected
calculate attack rates - examine distribution of cases by time and place
- look for interactions and relevant variables
- develop hypotheses, then test
- recommend control measures
attack rate
ppl who develop illness / total # ppl at risk
food specific attack rate
ppl who ate food and were ill / ppl who ate food
most cases of foodborne illness are…
sporadic, not outbreaks
how to diagnose foodborne illness
stool sample tested for bacteria, parasites, viruses
important clues to recognize foodborne illness
- incubation period and illness duration
- clinical symptoms
- population involved
additional clues to recognize foodborne illness
- food consumption (undercooked eggs, meats, unpasteurized milk/juice)
- other exposures (animal contact, foreign travel, job)
traceback investigation
restaurant > distributors > packers > suppliers
surveillance by health dept to track foodborne illness requirements
doc and lab report confirmed cases
doc reports clusters of 3+ patients with similar illness
bacterial isolates sent to DOH to compare samples
changes in food industry (2)
- centralized production with large producers
- globalization of food supply
centralized production issues
possibility of large outbreaks
low level contamination can cause outbreaks
difficult detection
large areas can be effected
globalization of food supply
rapid distribution of perishable supply
changing populations
- more elderly, immunocompromised persons
- changes in eating styles (increased dining out of house)
- immigration and travel (ethnic groups w/ diff food practices, souvenir foods with travelers)
what are foodborne outbreaks characterized by
- increase in cases above expected number
- contamination must happen
often combo of events: food is contaminated, then stored improperly
investigation components
- environmental sanitary inspection
- interviewing ill and sometimes well ppl using questionnaire
- molecular lab testing
- implement control measures (close restaurants, traceback, communicate with public)
what kind of outbreaks are easier to identify?
large, local outbreaks
what kind of outbreaks are harder to identify?
multistate outbreaks with cases in many places
case definition involves
person, place, time, and clinical features
example of case definition
person who ate at restaurant x and had diarrhea or vomiting within X days following his/her meal
norovirus aka
stomach flu
norovirus
causes vomiting and diarrhea
increase in winter (like flu)
transmitted btwn ppl (daycare, nursing homes)
cause foodborne outbreaks