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Study to rid cockles of Hepatitis A virus

09 May 2012

Researchers in the project: (from left) Dr Dwiono, Ms Ma, Prof Lam and Ms Chew. Dr Tan is not in the picture

Cockles are loved by many Singaporeans in dishes such as fried kway teow (flat rice noodles). Yet when consumed raw or partially cooked, cockles have been linked to Hepatitis A - a viral infection which makes the liver enlarged, inflamed and tender.

Now, an NUS group led by Emeritus Professor Lam Toong Jin from the Department of Biological Sciences aims to make cockles free of the virus.

The team - comprising Prof Lam, NUS Tropical Marine Science Institute researchers Dr Tan Koh Siang who is Co-Principal Investigator, Dr Sigit Dwiono, Ms Ma Aye Aye Mon and Ms Vicki Chew Yii Ching - has embarked on a three-year project with plans to grow cockles with fish.

Prof Lam explained that non-freshwater fish will be injected with a vaccine against the Hepatitis A virus, inducing them to produce antibodies which are released into the water. These antibodies may then be absorbed by the cockles, protecting them from the virus.

Since late last year, the researchers have been working to fine-tune the right vaccine dosage and ratio of fish to cockles. They are using sea bass to determine if these will keep the cockles virus-free, and how long the fish can produce antibodies before booster vaccine shots are given.

The project is made possible by a S$1 million grant by the Singapore Millennium Foundation, which is funded by the Temasek Trust.

According to the Singapore Health Promotion Board, the majority of reported Hepatitis A cases in Singapore had histories of consuming contaminated food from raw or partially cooked cockles. In fact, the consumption of shellfish from sewage-contaminated water is a common way of getting the virus. The symptoms of Hepatitis A include jaundice, fatigue, fever, loss of appetite, nausea, vomiting, pale-coloured stools, dark urine and itchy skin.

The researchers plan to construct a land-based farm as a pilot to breed the virus-free cockles for better control against pollution. Besides cockles, they are considering other shellfish which may also carry the Hepatitis A virus.

Looking ahead, Prof Lam will turn to aquaculture companies and investors for commercialisation.