A Foodborne Outbreak of Gastroenteritis Associated with Norwalk‐like Viruses: First Molecular Traceback to Deli Sandwiches Contaminated during Preparation

Abstract

In March 1998, an outbreak of acute gastroenteritis occurred among students at a Texas university. Overall, 125 ill students sought medical care. Case-control studies revealed that illness was significantly associated with eating foods from the university's main cafeteria deli bar on 9 and 10 March. Stool specimens from 9 (50%) of 18 ill students and samples of deli ham showed evidence of Norwalk-like viruses (NLVs) by reverse-transcriptase (RT) polymerase chain reaction (PCR) assay. A food handler who prepared sandwiches for lunch on 9 March reported that her infant had been sick with watery diarrhea since just before the outbreak. A stool sample from the infant was positive for NLV by RT-PCR, and the sequence of the amplified product was identical to that of amplified product from deli ham and students' stool specimens. This is the first time RT-PCR and sequence analysis have successfully confirmed viral contamination of a food item likely to have been contaminated by a food handler.

Norovirus Gastroenteritis

“…54 Assays that have been used in specific outbreaks to detect noroviruses directly in contaminated food and water are now being adapted to routine screening of food or water. 55,56 Current control efforts, which are only modestly effective at best, are aimed at limiting exposure to foods that have been contaminated at the source through environmental contamination (as has been the case with raspberries and oysters) or through contamination by food handlers. 57 It is recommended that ill food handlers not be allowed to remain on the job and that strict personal hygiene among food handlers be enforced, but both initiatives have had limited success.…”

A model of the transmission of micro-organisms in a public setting and its correlation to pathogen infection risks

“…It is assumed that the majority of such infections arise in the domestic environment (Scott and Bloomfield 1993;Barker and Bloomfield 2000;Daniels et al 2000), with kitchens and bathrooms serving as pathogen reservoirs (Gerba et al 1975;Scott et al 1982;Josephson et al 1997;Bellamy et al 1998;Rusin et al 1998;Barker and Bloomfield 2000;Kagan et al 2002;Curtis et al 2003). Not much data exist on the transmission of micro-organisms in chains for the infection of pathogenic bacteria, fungi and viruses in private bathrooms and toilets.…”

Detection of Noroviruses in Foods: A Study on Virus Extraction Procedures in Foods Implicated in Outbreaks of Human Gastroenteritis

“…Transmission has occurred by person-to-person contact (6) and through contaminated water (10,19) and food (20,36,37). Most of the food items implicated in these outbreaks are raw or uncooked, such as oysters, mussels, fruits, vegetables, sandwiches, dairy products, baked products, and salads, which are associated with high risks of infection (3,9,18,20,27,39,40). These foods are most likely contaminated through sewage-contaminated surface water or by infected food handlers during harvesting, packaging, or food preparation (9,35).…”

“…Most of the food items implicated in these outbreaks are raw or uncooked, such as oysters, mussels, fruits, vegetables, sandwiches, dairy products, baked products, and salads, which are associated with high risks of infection (3,9,18,20,27,39,40). These foods are most likely contaminated through sewage-contaminated surface water or by infected food handlers during harvesting, packaging, or food preparation (9,35). Epidemiological investigations of outbreaks have been hindered by a lack of animal models or cell culture systems for the detection of noroviruses and hepatitis A virus in foods other than shellfish.…”