Hepatitis A virus detection in oysters (Crassostrea gigas) in Santa Catarina State, Brazil, by reverse transcription-polymerase chain reaction.

Shellfish are readily contaminated with viruses present in water containing sewage because of the concentration effect of filter feeding. Hepatitis A virus (HAV) is the main cause of acute hepatitis worldwide and may lead to severe illness or even death. It is transmitted through fecal and oral routes and causes widespread endemic and asymptomatic infections in young children. Here we describe a method for the detection of HAV RNA in shellfish involving the extraction of total RNA from oyster meat followed by reverse transcription-polymerase chain reaction (RT-PCR). Virus recovery from oyster extracts artificially seeded with HAV strain HM 175 was examined by RT-PCR. The minimum detection limit was 3.3 focus-forming units of HAV, and the recovery rate was 75.7%. This method was used to assess the viral contamination of four shellfish beds in Santa Catarina State, Brazil, over a 1-year period. Six (22%) of 27 samples collected in autumn and winter from one shellfish bed tested positive for HAV.