How many foodborne outbreaks of Salmonella infection occurred in France in1995? Application of the capture-recapture method to three surveillance systems

Despite control measures, foodborne outbreaks of non-typhi Salmonella infec tion continue to occur in developed countries. The authors aimed to assess the number of foodborne Salmonella outbreaks that occurred in France in 199 5 using a capture-recapture approach, Data from three sources-the National Public Health Network (NPHN), the Ministry of Agriculture (MA), which recei ves mandatory notification, and the National Salmonella and Shigella Refere nce Center (NRC)-were collected. Matching algorithms permitted identificati on of matched outbreaks. The total number of outbreaks was estimated by log -linear modeling taking into account source dependencies and the variable c atchability. The final estimate was adjusted for the positive predictive va lue (66%) of the NRC case definition. The dependence between the NPHN and t he MA was also evaluated by means of a qualitative survey. A total of 716 f oodborne Salmonella outbreaks were reported to the three sources, and 108 m atches were identified. The best-fitting model, taking into account a posit ive dependence between the NPHN and MA sources, gave an estimate of 757 out breaks. The sensitivity was 15% for the NPHN, 10% for the MA, and 50% for t he NRC. In France, routine mandatory reporting of foodborne Salmonella outb reaks is very incomplete, and it is not representative of the serotype and the type of outbreak.