A national outbreak of Salmonella enteritidis infections from ice cream

• Published in: The New England journal of medicine Vol. 334; no. 20; pp. 1281 - 1286
• Main Authors: Hennessy, T.W. (Minnesota Department of Health, Minneapolis, MN.), Hedberg, C.W, Slutsker, L, White, K.E, Besser-Wiek, J.M, Moen, M.E, Feldman, J, Coleman, W.W, Edmonson, L.M, MacDonald, K.L
• Format: Journal Article
• Language: English
• Published: Boston, MA Massachusetts Medical Society 16.05.1996
• Subjects: ALIMENTOS; Bacterial diseases; Bacterial diseases of the digestive system and abdomen; Biological and medical sciences; CONTAMINACION; CONTAMINACION BIOLOGICA; CONTAMINATION; CONTAMINATION BIOLOGIQUE; CREME GLACEE; Eggs; ENFERMEDADES TRANSM POR ALIMENTOS; ENVENENAMIENTO; ETATS UNIS; EUA; GASTROENTERITE; GASTROENTERITIS; HELADO; HUEVOS; Human bacterial diseases; Ice cream; Infectious diseases; INTOXICATION; Laboratories; MALADIE TRANSMISSIBLE PAR ALIMENT; MANIPULACION; MANUTENTION; Medical sciences; MINNESOTA; OEUF; PASTEURISATION; PASTEURIZACION; PRODUIT ALIMENTAIRE; REMOLQUES; REMORQUE; Salmonella; SALMONELLA ENTERITIDIS; United States > US; Epidemic; Human; Salmonella enteritidis; Case control study; Epidemiology; Feeding; Infection; Bacteriosis; Food preservation; Digestive diseases; Bacteria; Salmonellosis; Ice cream; Enterobacteriaceae
• ISSN: 0028-4793; 1533-4406
• DOI: 10.1056/NEJM199605163342001

Background. In September 1994, the Minnesota Department of Health detected an increase in the number of reports of Salmonella enteritidis infections. After a case-control study implicated a nationally distributed brand of ice cream (Schwan's) in the outbreak, the product was recalled and further epidemiologic and microbiologic investigations were conducted. Methods. We defined an outbreak-associated case of S. enteritidis infection as one in which S. enteritidis was cultured from a person who became ill in September or October 1994. We established national surveillance and surveyed customers of the implicated manufacturer. The steps involved in the manufacture of ice cream associated with cases of S. enteritidis infection were compared with those of products not known to be associated with infection matched for the date of manufacture. Cultures for bacteria were obtained from ice cream samples, the ice cream plant, and tanker trailers that had transported the ice cream base (premix) to the plant. Results. We estimate that S. enteritidis gastroenteritis developed in 224,000 persons in the United States after they ate Schwan's ice cream. The attack rate for consumers was 6.6 percent. Ice cream associated with infection contained a higher percentage of premix that had been transported by tanker trailers that had carried nonpasteurized eggs immediately before (P=0.02). S. enteritidis was isolated from 8 of 266 ice cream products (3 percent), but not from environmental samples obtained from the ice cream plant (n= 157) or tanker trailers (n=204). Conclusions. This nationwide outbreak of salmonellosis was most likely the result of contamination of pasteurized ice cream premix during transport in tanker trailers that had previously carried nonpasteurized liquid eggs containing S. enteritidis. To prevent further outbreaks, food products not destined for repasteurization should be transported in dedicated containers