LARGE OUTBREAK OF SALMONELLA-ENTERICA SEROTYPE PARATYPHI-B INFECTION CAUSED BY A GOATS MILK CHEESE, FRANCE, 1993 - A CASE-FINDING AND EPIDEMIOLOGIC-STUDY

Objective-To assess the magnitude of a nationwide outbreak of infectio n with Salmonella enterica serotype paratyphi B and identify the vehic le and source of infection. Design - A case finding study of S paratyp hi B infection between 15 August and 30 November 1993; a pair matched case-control study; an environmental investigation at a processing pla nt that produced a raw goats' milk cheese incriminated in the outbreak ; phage typing and genotyping of food and human Sparatyphi B isolates. Setting - France, 15 August to 30 November 1993. Subjects - 273 patie nts with S paratyphi B infection; 59 pairs of cases and controls match ed for age, sex, and city of residence. Main outcome measures - Number s of cases and incidence rates by region of residence and age; matched odds ratios for dairy food preferences. Results - Among the 273 cases there was one death; 203 (78%) strains belonged to phage type 1 var 3 . The incidence of infection was greatest in the region where goats) m ilk cheese is commonly produced. Comparison of cases and controls show ed a 12-fold greater risk of illness (95% confidence interval 1.6 to 9 2.3) from eating brand A unpasteurised goats' milk cheese. Sparatyphi B isolates of phage type 1 var 3 were recovered from cheese A, goats' milk at the plant processing cheese A, and goats' milk supplied to the plant by a single farm. Genotypic IS 200 typing of food and human 1 v ar 3 phage type isolates showed a common IS 200 pattern. Conclusion - This outbreak emphasises the potential health hazards of widely distri buted unpasteurised milk products in France and the need for their clo se bacterial monitoring.