Academic journal article Journal of Environmental Health

An Outbreak of Norwalk-Like Viral Gastroenteritis in a Frequently Penalized Food Service Operation: A Case for Mandatory Training of Food Handlers in Safety and Hygiene. (Features)

Academic journal article Journal of Environmental Health

An Outbreak of Norwalk-Like Viral Gastroenteritis in a Frequently Penalized Food Service Operation: A Case for Mandatory Training of Food Handlers in Safety and Hygiene. (Features)

Article excerpt


In the United States, known pathogens account for an estimated 38.6 million food-related illnesses each year, of which 23 million (60 percent) are attributable to infection by Norwalk-like viruses (NLVs) (Mead et al., 1999). Norwalk-like viruses caused approximately 96 percent of the nonbacterial gastroenteritis outbreaks reported to 33 state health departments from January 1996 to June 1997, and eating at restaurants or at events with catered meals accounted for 26 percent of these outbreaks (Frankhauser, Noel, Monroe, Ando, & Glass, 1998). The re-emergence of food-related illness in the United States is believed to be due to many factors, including more frequent dining at restaurants and inadequate food safety and hygiene knowledge among food handlers (Kaferstein, Motarjemi, & Bettcher, 1997).

The mode of NLV transmission varies from ingestion of contaminated food or water to person-to-person transmission via direct contact, aerosol, or contaminated objects (Hedherg & Osterholm, 1993). According to a report by the Centers for Disease Control and Prevention (CDC), ingestion of potato salad by an infected food handler and person-to-person transmission were responsible for recent outbreaks of NLV in Alaska and Wisconsin, respectively (CDC, 2000). Raw oysters (Centers for Disease Control and Prevention [CDC], 1994, 1995; Kohn et al., 1995) and infected food handlers (Arness et al., 2000; Daniels et al., 2000; Kilgore et al., 1996) have been responsible for most NLV outbreaks in the United States.

In December 1999, an outbreak of acute gastroenteritis occurred among people who had eaten meals at a Christmas banquet in Toledo, Ohio. The meal had been prepared and served by a local caterer. On the basis of symptoms and onset, a Norwalk-like virus was suspected as the etiologic agent. The objectives of this study were as follows: 1) determine the cause of the outbreak and 2) evaluate the significance of food safety and hygiene training in preventing outbreaks.


Epidemiological Investigation

A case-control study was conducted to determine the cause of the outbreak. A standard case-history reporting form was used to record demographic characteristics, the onset and symptoms of the illnesses, and the types of foods eaten by both ill people and well people. A case of gastroenteritis was defined as an illness characterized by nausea, vomiting, or diarrhea occurring one to 96 hours after eating the meal. The controls were people who attended the dinner banquet and ate the meal but did not become sick.

Of the ill people who met the case definition, 25 agreed to provide stool samples for laboratory examination. Each person received a Cary-Blair (individually packaged tube containing two sterile swabs and a non-nutrient transport media), a small sterile container, and a standard instruction leaflet explaining how to collect an uncontaminated stool sample. After collection, both bulk and Cary-Blair stool samples were placed in sealable sandwich bags and kept in refrigerated condition during storage and transportation to the health department. Of the 25 people who agreed to provide samples, 12 did so within 48 to 72 hours of the onset of gastroenteritis symptoms. Stool samples were not, however, collected from any of the food handlers.

At the health department, all samples were placed in Styrofoam boxes containing dry ice and immediately transported to the Ohio Department of Health (ODH) in Columbus for examination. The Cary-Blair stool samples were examined for three enteropathogenic bacteria--Escherichia coli O157:H7, Salmonella, and Shigella--at an ODH laboratory according to ODH Standard Protocol, and the bulk stool samples were examined for NLVs with reverse transcriptase-polymerase chain reaction (RT-PCR) at a CDC laboratory in Atlanta, Georgia.

Environmental Investigation

The catering facility was inspected on December 8, 1999, and the manager was interviewed to determine whether food safety and hygiene violation had occurred during food preparation, storage, or serving. …

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