Jun 19, 2003 (CIDRAP News) Thousands of food handlers each year have hepatitis A and can potentially pass the disease to diners, a fact that poses tough problems for public health agencies, according to a report from the Centers for Disease Control and Prevention (CDC).
About 230,000 cases of hepatitis A were reported in the United States from 1992 through 2001, the CDC says in the Jun 20 issue of Morbidity and Mortality Weekly Report. Each year about 8% of adults who have hepatitis are identified as food handlers, indicating that thousands of food workers have the disease, the report says.
A food handler infected with hepatitis A virus (HAV) "potentially can transmit HAV to many others and cause a substantial economic burden to public health," the article says. The article describes a 2001 outbreak, linked with a Massachusetts restaurant, that involved at least 32 patients and caused estimated "societal costs" of about $800,000, more than 90% of which were paid by public health agencies.
A food handler carrying HAV was determined to be the probable cause of the outbreak, the report says. The worker's hepatitis case was reported to the state health department Oct 26, 2001, and he was believed to have been potentially infectious from Oct 3 to 24. He reported diligent handwashing and glove use while working, and supervisors corroborated this. He reported no gastrointestinal symptoms, and his duties were mainly managerial, though he did prepare some food, including sandwiches that were not cooked after preparation. Health officials judged that food contamination by the worker was unlikely and did not notify the public or recommend postexposure prophylaxis (PEP) for restaurant customers.
None of the other food handlers had hepatitis A symptoms, though they were not tested. The restaurant resumed business after a cleaning and inspection and after 19 food handlers received PEP and one was excluded from work, the report says.
A hepatitis A outbreak in the county where the restaurant is located surfaced in November, and by Dec 3 there were 46 cases, compared with none in the same period a year earlier. Of patients who could recall where they had eaten during their incubation period, 35 of 46 (76%) had eaten at the restaurant in question ("restaurant A"), versus much lower percentages for other local restaurants.
Investigators recruited local age-matched controls for each of 43 case-patients in an effort to determine whether patients were more likely to have eaten at restaurant A. Thirty-two of the 43 case-patients and 7 of 16 controls reported having eaten at restaurant A. A regression model linked illness with eating food from restaurant A (odds ratio, 29.4; 95% confidence interval, 5.1 to infinity) but not with eating food from any of three other restaurants. In addition, molecular studies on viral isolates from a subset of 28 case-patients showed identical RNA among all the patients who had eaten at restaurant A.
"This outbreak investigation highlights the difficulties faced by public health officials when making hepatitis A PEP decisions," the report states. How food was contaminated despite the ill worker's reportedly good hygiene is unknown, and transmission from another food handler with unidentified or unreported HAV infection "cannot be excluded." However, the report says the ill worker had a colostomy, which "might have compromised hygiene." HAV transmission from a food handler with a colostomy was previously reported to the CDC by a health official in Texas.
How hygiene, symptoms, and viral characteristics contribute to foodborne transmission of HAV remains imperfectly understood, the article says. But the risk can be reduced by thorough handwashing, wearing gloves when handling food that is not subsequently cooked, keeping ill people from directly handling food or food equipment, and providing adequate sick leave. In addition, hepatitis A vaccination is recommended for both food handlers and other groups routinely advised to get the shot (sexually active gay men, illicit-drug users, people traveling to countries with endemic disease), the report states.
Until the dynamics of foodborne transmission of HAV are better understood, decisions about offering PEP to restaurant customers will have to be based on case-patient interviews and the judgment and experience of public health officials, the report concludes.
CDC. Foodborne transmission of hepatitis AMassachusetts, 2001. MMWR 2003;52:24;565-7 [Full text]