[Investigation of a foodborne intoxication in a high-density penitentiary center]

On September 25 2005, more than 100 inmates (almost 5% of the 1,800 prison population) experienced sudden onset gastroenteritis. This outbreak was the largest foodborne outbreak described in a prison population in Spain. Our objective was to confirm the outbreak, identify risk factors, implement control measures, and provide recommendations.

We conducted a cohort analysis of a stratified random sample of all the inmates, a cohort analysis of the one of the prison blocks, and an environmental investigation.

A total of 221 inmates were selected, of which 196 were interviewed. Twenty-eight percent had gastroenteritis and the main symptoms were abdominal pain (85%) and diarrhea (71%). All foods consumed caused similar attack rates. Factors associated with the risk of illness were eating the entire portion of seafood cocktail at lunch or all of the fried shrimp at dinner on September 24 (RR = 2; 95% CI, 1.1-3.8, and RR = 1.8; 95% CI, 1.1-3.1). Analysis of one of the prison blocks yielded results similar to those of the random sample. Clostridium perfringens, Bacillus cereus and Escherichia coli were isolated from a sample of the seafood cocktail.

A gastroenteritis outbreak caused by several pa-thogens was confirmed. Both the reported symptoms and the calculated incubation periods corresponded to the pathogens isolated. Preparation of food in prison facilities should meet minimum safety standards, including refrigeration and training of food handlers.