Mussel-associated viral hepatitis, type A: serological confirmation.

Area of Science:

• Epidemiology
• Virology
• Foodborne Illness

Background:

• Acute viral hepatitis outbreaks can be linked to contaminated food sources.
• Shellfish, particularly mussels, are known to accumulate and transmit viruses.

Purpose of the Study:

• To identify the source and etiological agent of an acute viral hepatitis outbreak within a family.
• To confirm the role of hepatitis A virus (HAV) in the observed illness.

Main Methods:

• Epidemiological investigation including case-finding and exposure assessment.
• Statistical analysis of attack rates between consumers and non-consumers of suspect food.
• Serological confirmation of hepatitis A virus infection using immune adherence haemagglutination assay.

Main Results:

• Seven out of 14 family members developed acute viral hepatitis.
• A statistically significant higher attack rate (70%) was observed in individuals who consumed incompletely cooked mussels compared to non-consumers (0%) (P=0.035).
• Serological tests confirmed rising titres of antibodies to hepatitis A virus, related to the MS-1 strain.

Conclusions:

• Incompletely cooked mussels (Mytilus edulis) were identified as the likely vehicle for hepatitis A transmission in this family outbreak.
• The findings underscore the importance of proper cooking of shellfish to prevent viral hepatitis transmission.
• Hepatitis A virus was confirmed as the causative agent through serological evidence.