Update: Salmonella enteritidis Infections and Grade A Shell Eggs -- United States

Salmonella enteritidis (SE) continues to be an important cause of outbreaks of gastroenteritis. This report describes recent outbreaks of SE infections that have been associated with Grade A eggs.

Fort Monmouth, New Jersey. From May 3 to May 9, 1988, 88 (47%) of 188 students in a New Jersey college preparatory school developed febrile gastroenteritis. Symptoms included diarrhea, abdominal pain, headache, and fever. Twenty-seven (31%) of the ill students were hospitalized, and all recovered; stool cultures from each ill patient yielded SE. An epidemiologic investigation indicated that homemade ice cream prepared with Grade A raw eggs only 2 hours before consumption was the source of the outbreak. A culture of the implicated ice cream yielded SE. The ice cream had been properly cooled, and no food handling errors were identified.

Asbury Park, New Jersey. An outbreak of SE infections was reported in a group of 100 service organization trainees who had stayed at the same hotel in Asbury Park, New Jersey. Forty-seven (60%) of 78 trainees interviewed reported having had onset of gastrointestinal illness from June 13 to June 16, 1988. Two were hospitalized and recovered; seven stool cultures were taken, and all yielded SE. Epidemiologic data implicated scrambled eggs served on June 11 and 12. In addition, culture of a pooled egg mixture obtained at the hotel yielded SE. Neither the clinical isolates nor the isolate from the eggs were lysine-positive. Since most SE isolates are lysine-positive, a relationship between the SE strains found in the patients and in the eggs seems probable. The implicated Grade A eggs were traced to a farm in Pennsylvania.

Livonia, New York. In late May 1988, an outbreak of gastrointestinal illness occurred among patrons of a restaurant in Livonia, New York. Twelve (38%) of 32 persons who attended a brunch on May 22 reported diarrhea, nausea, vomiting, or abdominal cramps. Stool cultures from four patients yielded SE. Egg omelets made from pooled Grade A eggs were the only food statistically associated with illness. Investigation did not identify improper food handling practices, such as cross-contamination or inadequate storage, which could have played a role in this outbreak. None of the food handlers were ill, and none had stool cultures that yielded Salmonella. The implicated Grade A eggs were traced to a Maryland farm. Reported by: GC Taylor, MPH, Fort Monmouth; MA Meadows, LW Jargowsky, MPH, Monmouth County Dept of Health; K Pilot, MJ Teter, DO, J Brook, MD, ME Petrone, MD, KC Spitalny, MD, State Epidemiologist, New Jersey State Dept of Health. SB Spitz, MS, Monroe County Dept of Health; RJ Davin, J Ellison, Livingston County Dept of Health; SF Kondracki, JJ Guzewich, MPH, JK Fudala, MS, JG Debbie, DVM, DL Morse, MD, State Epidemiologist, New York State Dept of Health. Enteric Diseases Br, Div of Bacterial Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: A total of 6390 SE isolates were reported for 1987 (16% of total reported Salmonella isolates). SE is the second most common Salmonella serotype reported. National surveillance data for 1987 indicate continued high isolation rates of SE in the northeast, mid-Atlantic, and south Atlantic regions (Figure 1). Recent isolation rates of SE have also increased in the east north central, mountain, and Pacific regions of the country. The outbreaks described in this report confirm the continuing association between eggs and outbreaks of SE infections (1). Of the 19 outbreaks caused by SE with a known vehicle reported to CDC in 1987, 15 (79%) were associated with Grade A shell eggs. No vehicle of transmission was known for 11 other reported outbreaks of SE infections in 1987. An examination of data from 1973 to 1987 reveals that most outbreaks caused by SE occur during the summer months (Figure 2). Warm temperatures may provide opportunities for SE to multiply and survive in the eggs during production, transport, storage, or use.

Although food handling errors can contribute to outbreaks of Salmonella infections, the outbreaks in Fort Monmouth, New Jersey (ice cream), and Livonia, New York (egg omelet), demonstrate that SE infections can occur even when acceptable food preparation techniques have been used.

An SE control program is being developed by state health departments, poultry scientists, the egg industry, the U.S. Department of Agriculture, the Food and Drug Administration, and CDC. Long-term control of SE may depend on the elimination of infected flocks or use of pasteurized egg products. Proper handling and cooking of eggs can minimize the risk of salmonellosis (2); thorough cooking kills Salmonella.*

Clinicians are encouraged to report cases of salmonellosis to local and state health departments. Salmonella isolates can be serotyped by most state public health laboratories to aid in epidemiologic investigations.

References

1. St. Louis ME, Morse DL, Potter ME, et al. The emergence of grade A eggs as a major source of Salmonella enteritidis infections: new implications for the control of salmonellosis. JAMA 1988;259:2103-7.

2. CDC. Update: Salmonella enteritidis infections in the northeastern United States. MMWR 1987;36:204-5. *Further information about proper food preparation with eggs can be obtained through local county extension home economists or by calling the USDA Meat and Poultry Hotline (800) 535- 4555.

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