An increase in sporadic and outbreak-associated Salmonella enteritidis infections in Wisconsin: The role of eggs. Journal of Infectious Diseases

more than doubled compared with the previous 9 years. A case±control study was conducted to determine risk factors for sporadic infections, and results of outbreak investigations were reviewed. Eating raw eggs (matched odds ratio; 95 % con®dence interval [CI],[MOR] = 14.5 1.72591.6), eating raw or undercooked eggs ( ; 95 % CI, 1.3228.0), eating any eggsMOR = 5.8 ( ; 95 % CI, 1.2216.2), and dining at a restaurant ( ; 95 % CI, 1.4±18.4)MOR = 4.2 MOR = 4.7 were associated with infection in the case±control study. For 3 of the 8 outbreaks, a probable source was identi®ed, in each instance, foods containing eggs. Human infections decreased after eggs were diverted from implicated ¯ocks. This epidemic demonstrates the continuing need for quality assurance on egg farms and enhanced education of consumers and commercial food preparers regarding safe handling of eggs. Since the 1970s, the incidence of Salmonella enterica serotype enteritidis (SE) infections has increased in European and North and South American countries [1]. In the United States from 1972 to 1996, the proportion of Salmonella isolates that were SE increased from 6 % to 25%, making SE the predominant Salmonella serotype [2]. Investigations of outbreaks [3±5] and sporadic SE infections [6±9] have most frequently identi®ed eating raw or undercooked eggs as the principal risk factor for human illness