Epidemiology and Infection



The pandemic of Salmonella Enteritidis phage type 4 reaches Utah: a complex investigation confirms the need for continuing rigorous control measures


J. SOBEL a1c1, A. B. HIRSHFELD a1, K. McTIGUE a1, C. L. BURNETT a2, S. ALTEKRUSE a3, F. BRENNER a1, G. MALCOLM a1, S. L. MOTTICE a4, C. R. NICHOLS a2 and D. L. SWERDLOW a1
a1 Foodborne and Diarrheal Diseases Branch, Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, MS-A38, 1600 Clifton Rd., NE, Atlanta, GA 30333, USA
a2 State of Utah, Department of Health, Bureau of Epidemiology, Salt Lake City, UT, USA
a3 Office of Scientific Assessment and Support, Center for Food Safety and Applied Nutrition, Food and Drug Administration, Washington, DC, USA
a4 State of Utah, Department of Health, Division of Epidemiology and Laboratory Services, Salt Lake City, UT, USA

Abstract

In 1995, Salmonella Enteritidis (SE) cases in the state of Utah increased fivefold. Isolates were identified as phage type 4 (PT4). Risk factors and sources of infection were investigated in two case-control studies, a traceback of implicated foods, and environmental testing. Forty-three patients with sporadic infections and 86 controls were included in a case-control study of risk factors for infection. A follow-up case-control study of 25 case and 19 control restaurants patronized by case and control patients examined risks associated with restaurant practices. In the first case-control study, restaurant dining was associated with illness (P = 0·002). In the follow-up case-control study, case restaurants were likelier to use > 2000 eggs per week (P < 0·02), to pool eggs (P < 0·05), and to use eggs from cooperative ‘A’ (P < 0·009). Eggs implicated in separately investigated SE PT4 outbreaks were traced to cooperative ‘A’, and SE PT4 was cultured from one of the cooperative's five local farms. We conclude that SE PT4 transmitted by infected eggs from a single farm caused a fivefold increase in human infections in Utah.

(Accepted April 26 2000)


Correspondence:
c1 Author for correspondence.


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