Swimming-associated outbreak of Escherichia coli O157:H7.
In 1997 the first outbreak of Escherichia coli O157:H7 infections involving 14 cases occurred in Finland. A case was defined as a resident of Alavus with an episode of diarrhoea between 5 and 17 July 1997, and from whom E. coli O157:H7 was isolated from stool. The investigation included case searching and a population-based case control study. Five primary and eight symptomatic secondary cases of E. coli O157:H7 illness were detected. In the 10 days before the outbreak, all 5 primary patients (aged 3-8 years), but only 6 of 32 population controls from the same age range (Fisher's test, P < 0.001) and 4 of 10 sibling controls (P < 0.05) had visited (but had not necessarily bathed in) a shallow beach popular among young children. Four out of 5 primary cases had remained within 5 m of the beach while swimming and had swallowed lake water compared to 1 of 5 population controls. These analytical epidemiologic findings incriminated fresh lake water as the vehicle of E. coli O157:H7 transmission.
Paunio
M
M
University of Helsinki, Department of Public Health, Mannerheimintie, Finland.
Pebody
R
R
Keskimäki
M
M
Kokki
M
M
Ruutu
P
P
Oinonen
S
S
Vuotari
V
V
Siitonen
A
A
Lahti
E
E
Leinikki
P
P
D017677:Age Distribution; D001493:Bathing Beaches / Q000706:statistics & numerical data*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D003967:Diarrhea / Q000453:epidemiology / Q000209:etiology* / Q000382:microbiology; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000209:etiology* / Q000382:microbiology / Q000635:transmission; D019453:Escherichia coli O157; D005387:Finland / Q000453:epidemiology; D005618:Fresh Water / Q000382:microbiology*; D006801:Humans; D011159:Population Surveillance; D012621:Seasons; D011795:Surveys and Questionnaires; D013550:Swimming / Q000706:statistics & numerical data*