[Shigellosis outbreak with 146 cases related to a fair].
BACKGROUND
On September 3, 2005, the Ciudad Real Public Health Service (Spain) received a report of 20 cases of gastroenteritis in the municipality of Daimiel. We conducted an investigation to determine the cause or causes of the outbreak and to implement control measures. Most of the cases involved young people who visited the municipality's fair.


METHODS
We carried out a descriptive study and an analytic case-control study. In the descriptive study, all variables of interest available in the medical records were included. In the case-control study, each case was matched with a control by age (plus or minus 5 years), gender, and attendance at the fair. Sixty-five cases and 65 controls were finally included in the study. Samples of foods and stools from food handlers were taken.


RESULTS
We found 196 cases, 146 of which were confirmed. The epidemic curve suggested a common source of infection with a short period of activity. The case-control study showed an association between infection and eating potatoes with a sauce at any of the fair's five food stalls (OR = 20.56; 95%CI, 6.15-75.93; p < 0.0001). Logistic regression analysis showed an association with eating potatoes in food stall number 2 (OR = 6.38; 95%CI, 1.70-23.90; p < 0.0059). Neither samples of foods nor stools from food handlers yielded any positive results. However, Shigella sonnei was isolated from stool samples from 20 cases.


CONCLUSIONS
The epidemiological study suggested that the most probable cause of the outbreak was a sauce, handmade with garlic, milk, and oil and served with the potatoes.
Castell Monsalve
Juan
J
Delegación Provincial de Sanidad, Consejería de Sanidad de la Junta de Comunidades de Castilla La Mancha, Ciudad Real, España. jcastell@jccm.es
Gutiérrez Avila
Gonzalo
G
Rodolfo Saavedra
Remedios
R
Santos Azorín
Antonia
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D004405:Dysentery, Bacillary / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology; D005243:Feces / Q000382:microbiology; D005260:Female; D005517:Foodborne Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012621:Seasons; D012764:Shigella sonnei / Q000302:isolation & purification; D013030:Spain / Q000453:epidemiology