Diane Joy Galos

Philippine shellfish have always been a staple of the local seafood scene, but with hepatitis A making its way through the waters, those prized oysters and mussels are starting to look a little less appetizing and a lot more dangerous.


Scientists from Ateneo de Manila University, the University of the Philippines, Monash University Malaysia Selangor, and the Bureau of Fisheries and Aquatic Resources have raised concerns about the lack of monitoring for Hepatitis A (HAV) in local shellfish such as oysters and mollusks.

The study, published in the Philippine Journal of Science in August 2024, warned that insufficient data on HAV transmission in the Philippines poses a significant public health risk.

“The fact that hepatitis A is very contagious and that Filipinos living along the coastal areas are susceptible to contaminated fresh products still renders significant public concern,” the study mentioned.

Hepatitis A is a liver disease that usually resolves without long-term damage, though in rare cases, it can lead to liver failure, according to the United States Centers for Disease Control and Prevention.

The researchers warned that although the wider Philippine public is aware of the dangers from other food safety concerns such as “red tide,” there is little public awareness of the dangers from HAV and other viruses.

HAV spreads to people through food and water that has been contaminated by fecal matter from infected animals that have not been cleaned and cooked properly.

“HAV is particularly high from ingesting poorly prepared shellfish such as oysters and mussels,” the study noted, since these animals are filter feeders that process large amounts of potentially contaminated water.

The virus can survive up to ten weeks in shellfish, and current food safety methods, including freezing and cooking, may not fully eliminate HAV.

Despite food safety regulations, local shellfish are only tested for E. coli and salmonella, not HAV.

“Perceived health risks related to seafood consumption are limited to red tide or mass fish kill,” the study added, urging routine HAV monitoring by BFAR.

The scientists also called for further research on how food processes, cooking, and storage conditions affect HAV levels in shellfish.

“There are no consistent monitoring programs for HAV in local shellfish and the environment,” the study said, warning of difficulties in early outbreak detection.

The World Health Organization recommends prevention through improved sanitation, food safety, and immunization, as there is no specific treatment for HAV.