Key Findings - Summary of the exploratory investigation following the unusual increase in the number of Salmonella serotypes 4, 5, and 12:I:- isolated in France

In 2011, several clusters of salmonellosis caused by serotype 4,5,12:i:- were investigated by the CIREs, but no common source or exposure could be identified (see Epidemiological Bulletin 281 of July 29). Against the backdrop of a continuous increase in the number of serotype 4,5,12:i:- strains—a monophasic variant of S. Typhimurium (ST)—an unusual rise in the number of these strains received by the CNR Salmonella and isolated was reported to the InVS for August and September 2011. To identify a potential source still in circulation and guide investigations by the DGAL and ANSES, the InVS, in collaboration with the CIREs, conducted an exploratory survey using standardized questionnaires by telephoning all cases reported by the CNR for weeks 41 and 42. (See Epidemiological Bulletin No. 294 of October 27). Of the 137 identified cases, 23 could not be contacted, and 10 refused to participate. The response rate was 73%. The median age of the cases interviewed was 4 years, and nearly 65% of the cases were under 15 years of age. The sex ratio was 1.43. The symptoms reported were: diarrhea (93%), including bloody diarrhea (47%), fever (78%), and vomiting (36%). Among these cases, 39% were hospitalized. No deaths occurred. Several dietary intake analyses were conducted, and it was not possible to identify any specific dietary pattern for all cases or for certain subgroups. This increase in the number of serotype 4,5,12:i:- strains is still under investigation, as the CNR, after noting a decrease in strains, has reported a new increase in the number of strains received over the past 3 weeks.