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Immunoglobulin M-specific serologic testing in an outbreak of foodborne viral hepatitis, type A
Abstract:
Ninety-seven symptomatic and five asymptomatic infections with viral hepatitis, type A (102 cases) were identified in members, guests and employees of a private country club in an outbreak associated with consuming food and ice prepared or handled by an employee of the club's kitchen pantry. Twenty-three symptomatic persons were tested by differential radioimmunoassay for immunoglobulin M (IgM) (acute-phase) hepatitis A antibody (anti-HAV) and all 23 were documented to be infected with hepatitis A virus (HAV). Forty-one member/guest cases had only a single exposure at the county club. Their incubation periods ranged from 21 to 40 days, with a mean of 30 days. The exposure of these single-day patrons occurred over a 14-day period. The index case was not icteric and only moderately symptomatic and was diagnosed retrospectively to have viral hepatitis, type A by serologic determination of IgM anti-HAV in blood samples. Four items implicated in disease transmission were potato salad, hot dogs, molded salmon and ice handled by the index case. Serologic screening of controls did not appear to alter the conclusions of the food item analysis.
Insights
A hepatitis A outbreak occurred at a country club, infecting 102 people through contaminated food and ice. The index case, a kitchen employee, was moderately symptomatic, highlighting the risk of foodborne hepatitis A virus transmission.
Area of Science:
- Epidemiology
- Infectious Diseases
- Public Health
Background:
- Hepatitis A virus (HAV) is a significant cause of infectious hepatitis.
- Outbreaks can occur through contaminated food and water, posing a public health risk.
- Identifying the source and transmission routes is crucial for outbreak control.
Purpose of the Study:
- To investigate a hepatitis A outbreak at a private country club.
- To identify the source and vehicles of HAV transmission.
- To determine the incubation period and characteristics of the outbreak.
Main Methods:
- Case finding of symptomatic and asymptomatic infections among club members, guests, and employees.
- Serologic testing using differential radioimmunoassay for immunoglobulin M (IgM) anti-HAV.
- Retrospective analysis of food and ice consumption patterns.
- Interviews and exposure history collection from cases and controls.
Main Results:
- 102 cases of hepatitis A were identified, including 97 symptomatic and 5 asymptomatic infections.
- The outbreak was linked to food and ice handled by a single kitchen pantry employee.
- Implicated food items included potato salad, hot dogs, molded salmon, and ice.
- The incubation period ranged from 21 to 40 days, with a mean of 30 days.
Conclusions:
- Contaminated food and ice handled by an infected food handler were the primary sources of HAV transmission.
- The index case, though moderately symptomatic, played a key role in the outbreak.
- Effective control measures require strict food safety practices and prompt identification of infected individuals in food service settings.