Epidemiologic investigation of a restaurant-associated outbreak of Pontiac fever.
This case-control study investigated a cluster of respiratory illness among patrons of a restaurant. Of 173 patrons interviewed, 117 (68%) were ill. Symptoms included myalgias (93%), headache (87%), and fatigue (79%). The mean incubation period was 49 h and the mean duration of illness was 71 h. Patrons aged >15 years were more likely to have been ill than younger patrons (odds ratio [OR], 2.96; P=.002); 58% of persons who were ill sat near a large fountain, compared with 18% of respondents who were not ill (OR, 7.5; P=.005). Legionella anisa was cultured from water samples obtained from the fountain pool. Of 22 individuals who were ill, 11 (50%) had a > or =4-fold increase in the titer of antibody to that strain of L. anisa from acute-phase to convalescent-phase serum samples; 3 others (14%) had persistently elevated titers of > or =512; of a group of 20 individuals who had not been exposed to the restaurant, none had titers of >128. Pontiac fever should be considered as a diagnosis during acute outbreaks of influenza-like illness with a high attack rate and no other identified etiology.
Tennessee Department of Health, Nashville, TN 37247, USA. tim.f.jones@state.tn.us
Timothy F
TF
Jones
Robert F
RF
Benson
Ellen W
EW
Brown
Jerry R
JR
Rowland
Steven C
SC
Crosier
William
W
Schaffner
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D006801:Humans; D007875:Legionella / Q000302:isolation & purification*; D007877:Legionnaires' Disease / Q000453:epidemiology* / Q000382:microbiology; D008875:Middle Aged; D012147:Restaurants; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology; D014871:Water Microbiology