Occurrence of hepatitis A virus in Philippine cupped oysters (Magallana bilineata) and green mussels (Perna viridis) collected in the Philippines

Hepatitis A virus (HAV) causes acute hepatitis through ingestion of contaminated food and water, with bivalve molluscs as common vehicles of transmission. As filter feeders, HAV concentrates in their digestive tissues when grown in contaminated waters. In 2020, the Philippines produced nearly 75 MT of shellfish. However, maintaining proper sanitation in growing areas remains challenging, and data on the occurrence of HAV in these commercially significant shellfish is lacking. This study aimed to detect HAV in Philippine cupped oysters ( Magallana bilineata ), green mussels ( Perna viridis ), and seawater from their growing areas. Samples were collected in Pangasinan (August 2022), Cavite (April 2023), and Capiz (June 2023), and HAV detection was conducted using quantitative reverse transcription polymerase chain reaction (RT-qPCR). HAV RNA was not detected in the shellfish and seawater samples, consistent with zero reported cases of Hepatitis A during the collection periods. However, a disparity was noted between these findings and potential sewage run-off linked to net positive rainfall. The Department of Health reported 111 and 127 Hepatitis A cases nationwide in 2022 and 2023, respectively, indicating that HAV remains endemic. Identifying sources, transmission modes, and environmental factors is crucial for integrating HAV risks into the food safety risk assessment framework.