Minnesota Department of Health (MDH) Bug Bytes
December 11, 2002
Vol. 3: No. 15
1. Viral Gastroenteritis Abounds (and
Please Don't Call it the "Flu")
Along with several local health departments, we have been busy investigating numerous (>10) outbreaks of gastroenteritis, including those associated with restaurants, wedding receptions, nursing homes, hospitals, and private parties. All outbreaks had clinical and epidemiologic characteristics suggestive of Norwalk-like virus (NLV)(stool specimens negative for bacterial and parasitic pathogens, greater than half of the ill had vomiting or vomiting was more common than fever, mean incubation period of 24-48 hours, and duration of illness 12-60 hours). In nine of these outbreaks, we obtained stool samples from ill persons and NLV was detected by PCR in our laboratory. Additional genotype sequencing was conducted by our lab on positive viral samples and showed a diversity of genotypes between outbreaks, with a common type occurring within each single outbreak. The source of infection has not been determined for all of the outbreaks but most appear to be related to fecal contamination of food by foodhandlers rather than by a food ingredient contaminated at its source outside of the setting.
We have previously demonstrated that the majority of foodborne outbreaks in Minnesota are due to NLVs. You may have read the numerous press accounts of the recent ongoing outbreaks aboard cruise ships. Cruise ship NLV outbreaks have been well documented in the past. It's unclear if the current situation is a true increase; it's likely that what's happening on ships is merely a reflection of what's happening on land with ample opportunities for amplification of illness in the close community on a ship. There have been recent alerts in Iowa and Edmonton, Alberta of an increase in gastroenteritis outbreaks. NLV outbreaks have also been reported in other Canadian province hospitals.
Media stories often mistakenly report these gastroenteritis events as "stomach flu" or the "flu" which leads to much confusion with influenza. The public often comments to us that they're surprised they've gotten gastroenteritis since they had gotten vaccination for influenza! There is nothing in common between viral gastroenteritis and influenza! Spread this word and we'd be very appreciative.
2. Salmonella Typhimirium Averted
With our active surveillance system, real time PFGE subtyping, and an aggressive public health response we are able to take action that prevents illness. Such was the case on the day before Thanksgiving when we became aware of 4 cases of Salmonella Typhimrium, all of the same PFGE subtype. These cases had been reported through routine surveillance and laboratory submission of isolates (thank you, once again, physicians, ICPs and labs!).
After interviewing three case-patients (two Thanksgiving eve) we determined that all three had eaten at the same restaurant/entertainment club in the 72 hours preceding their illnesses (they had eaten on 11/13, 11/14, or 11/16). Late Thanksgiving eve, we notified the local health department that licenses the facility, and local health department (City of Minneapolis) sanitarians went out to the restaurant late that evening, Thanksgiving day, and the day after Thanksgiving to investigate (who says government workers don't work hard?). Due to unsanitary conditions and an improper design of the kitchen and menu to support food safety, the facility was issued an emergency closure.
To date, we have identified 14 cases among patrons of the restaurant. Nine of the 14 are laboratory confirmed. Three of them were hospitalized for their illness. Meal dates ranged from 11/13-11/25. Ten employee stool specimens tested positive for Salmonella Typhimurium. PFGE results are available for four of these 10 and they matched to the patrons/case patients' strain. Only half of the workers who tested positive for Salmonella reported having gastrointestinal symptoms in the month prior to the investigation. Foodworkers who reported illness had onset of symptoms as far back as October 20, representing an ongoing, but undetected, risk at this facility. Infected foodworkers and environmental contamination can serve as bacterial reservoirs that can prolong the duration of an outbreak by contaminating a variety of foods served to patrons over time. Thus, it appears that there was an ongoing problem at this restaurant of ill foodworkers with Salmonella, and possibly a contaminated environment. The risk to patrons was ongoing and our actions likely prevented additional illnesses.
3. Smallpox Vaccination
This past Monday we submitted a plan to the Centers for Disease Control and Prevention for vaccinating selected patient health care providers and public health workers for smallpox. In June and October 2002, the Advisory Committee on Immunization Practices met and made recommendations on the use of smallpox vaccine. They advised that voluntary vaccination be offered to health care providers who would provide around the clock care for a smallpox case for the first 7-10 days. This offer would be made at every hospital in the country (approximately 62 in Minnesota) capable of hospitalizing a smallpox patient in a negative air pressure isolation room. The health care team would include emergency room staff, intensive care unit staff, general medical unit staff, medical house staff, medical specialists (infectious disease, dermatology, ophthalmology, pathology, surgery, anesthesiology), infection control professionals, respiratory therapists, radiology technicians, security personnel, and housekeeping staff. The public health workers would include vaccinators and disease investigators who would have face-to-face contact with smallpox case-patients.
Our plan calls for vaccinating approximately 10,000 persons
in Minnesota. The program would begin soon after the President
makes an announcement. More information on smallpox, ACIP
recommendations, and plans are on the CDC and MDH websites
Bug Bytes is a combined effort of the Infectious Disease Epidemiology, Prevention and Control Division and the Public Health Laboratory Division of MDH. We provide Bug Bytes as a way to say THANK YOU to the infection control professionals, laboratorians, local public health professionals, and health care providers who assist us.
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