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Epidemiologic Notes and Reports Increasing Rate of Salmonella Enteritidis Infections in the Northeastern United States

In the last 10 years, New England and the Middle Atlantic region* have experienced a fivefold increase in the reported isolation rate of Salmonella enteritidis (Figure 3). The increase exceeds the regional 1.7-fold increase in the collective isolation rate reported for all other Salmonella serotypes. In 1985, S. enteritidis replaced S. typhimurium as the single most commonly reported serotype in New Jersey, New York, and New Hampshire. The reasons for this increase are not understood. The median age of persons infected with S. enteritidis increased from 10 years to 24 years between 1975 and 1985, but the seasonality of the infections has not changed. In 1986, investigations of outbreaks of S. enteritidis infections in the northeastern United States implicated a variety of food vehicles, including scrambled eggs in Connecticut, a liquid protein supplement in Pennsylvania, home-made ziti in New Jersey, Italian-style rice balls in New York City, Hollandaise sauce in New York State, roast beef in Massachusetts, and one brand of commercial frozen pasta products in multiple states in the region. No single reservoir that would connect all of these outbreaks and the many sporadically occurring cases has been detected.

On November 1, 1986, epidemiologists from state health departments in the Northeast and the CDC met to review the findings of recent S. enteritidis outbreak investigations and to discuss possible approaches to the improved understanding and control of S. enteritidis infections in the region. An S. enteritidis Working Group was established to facilitate communication and cooperation among public health officials in several states and the CDC in the investigation of S. enteritidis outbreaks. Since the serogroup of a Salmonella isolate is often known before its serotype and because more than 90% of Group D isolates in the Northeast are S. enteritidis, a strategy was developed to intensify the rapid investigation of outbreaks of Group D Salmonella in the region. The U.S. Department of Agriculture and the Food and Drug Administration are assisting the S. enteritidis Working Group in investigations that suggest a food production or food processing source for the contamination. Reported by S Schultz, MD, Bur of Preventable Diseases, New York City Dept of Health, D Morse, MD, State Epidemiologist, New York Dept of Health; W Parkin, MD, State Epidemiologist, New Jersey Dept of Health; GF Grady, MD, State Epidemiologist, Bur of Communicable Diseases, Massachusetts Dept of Public Health; EJ Witte, VMD, MPH, State Epidemiologist, Pennsylvania Dept of Health; JL Hadler, MD, MPH, Connecticut Dept of Health Svcs; RL Vogt, MD, State Epidemiologist, Vermont Dept of Health; E Schwartz, MD, State Epidemiologist, New Hampshire Dept of Health and Welfare; KF Gensheimer, MD, State Epidemiologist, Maine Dept of Human Svcs; PR Silverman, PhD, State Epidemiologist, Delaware Dept of Health and Social Svcs; E Israel, MD, State Epidemiologist, Maryland Dept of Health and Mental Hygiene; Div of Field Services, Epidemiology Program Office, Enteric Diseases Br, Div of Bacterial Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: The majority of outbreaks of non-typhoid Salmonella infections in the United States come from foods of animal origin, and this is also likely to be the case for S. enteritidis (1). Salmonella may be introduced into such foods on the farm, during slaughter or processing, or during final food preparation. A broad increase in regional rates of human infections by a specific Salmonella serotype indicates that a regional increase in contamination may have occurred at one or more of these steps in the food chain.

Recognition of the problem of S. enteritidis infections in the northeastern United States and the intensive investigation proposed by the S. enteritidis Working Group are both made possible by routine serotyping of Salmonella isolates in public health laboratories. It is hoped that the regional effort proposed by the S. enteritidis Working Group to understand the epidemiology of S. enteritidis infections in the Northeast will lead to specific control measures for S. enteritidis. Understanding the epidemiology of a specific serotype in a region of high incidence may also lead to a better understanding of the continuing long-term increase in salmonellosis in the United States.


  1. Feldman RA, Riley LW. Epidemiology of Salmonella and Shigella infections in the United States. In: Takeda Y, Miwatani T, eds. Bacterial Diarrheal Diseases. Tokyo: KTK Scientific Publishers, 1985:103-16. *New Jersey, New York, and Pennsylvania.

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