Fx. Riedo et al., A POINT-SOURCE FOODBORNE LISTERIOSIS OUTBREAK - DOCUMENTED INCUBATIONPERIOD AND POSSIBLE MILD ILLNESS, The Journal of infectious diseases, 170(3), 1994, pp. 693-696
Listeria bacteremia occurred in 2 pregnant women whose only common exp
osure was attendance at a party. The incubation period, the possibilit
y of mild disease due to Listeria infection, and foods associated with
risk of disease were evaluated. Ten (28%) of 36 party attenders met a
case definition, which included isolation of Listeria monocytogenes f
rom blood or stool or two of the following: fever, musculoskeletal sym
ptoms, nausea, vomiting, diarrhea. One of 25 stool cultures was positi
ve. The 2 blood isolates and 1 stool isolate were serotype 4b and iden
tical by enzyme typing. The incubation periods for illness in the 2 pr
egnant women were 19 and 23 days. Consumption of large amounts of shri
mp, nonalcoholic beverages, Camembert cheese, and cauliflower was sign
ificantly associated with illness. Eating shrimp remained a significan
t risk factor for illness after controlling for consumption of other f
oods. This study suggests a milder illness may exist in healthy person
s who consume foods contaminated with L. monocytogenes and demonstrate
s a prolonged incubation period for disease.