SINGAPORE – Lovers of under-cooked pig liver could be at higher risk of hepatitis E virus (HEV) infection, as a new study has found similarities between a strain of the bug found in humans and that in raw pig liver bought from local markets.

The finding would be a concern for people with weak immune systems, as HEV infection is more serious for these people.

This is even as the study found that HEV infection among Singapore residents has risen significantly over the years.

Researchers at Singapore General Hospital (SGH) discovered that the HEV strain in three in four samples of infected patients’ blood has similar genetic features as the virus detected in three raw pork liver samples that were bought from local markets.

Although the researchers could not determine if pig liver is the main contributor of HEV cases in Singapore, they observed that pig liver can be found in many local dishes, said Dr Chan Kwai Peng, a senior author of the study.

“As most people like it a little under-cooked for its texture, this may put them at risk of hepatitis E infection,” said Dr Chan, a senior consultant in the Department of Microbiology at SGH.

HEV is a virus that infects the liver.

Most patients show no symptoms, but when they do, symptoms include fever, lethargy, nausea and jaundice.

The infection usually goes away on its own after a few weeks and does not lead to long-term illness or liver damage.

However, the infection can be dangerous for anyone with weak immune systems like transplant patients, or people with pre-existing chronic liver disease. It can cause severe liver disease or liver failure which can lead to death.

The infection can also be dangerous for pregnant women, but the HEV strains that affect pregnant women are not common in Singapore.

HEV can be contracted by drinking water contaminated with faeces, or by eating raw or under-cooked products from infected animals.

The study, which was led by SGH, found that the incidence of HEV among Singapore residents has more than doubled, from 1.7 cases per 100,000 residents in 2012, to 4.1 cases per 100,000 residents in 2016.

HEV infected people in the study tended to be Chinese men aged 55 years and above.

In 2017, a strain of HEV linked to pig farms in various European countries and dubbed the “Brexit virus”, was found to be infecting more than 60,000 people in Britain yearly.

At the time, the virus was reportedly found in meat from farms in France, the Netherlands, Germany and Denmark. It was contracted by eating infected pork products.

How then can people protect themselves from getting infected by HEV when it comes to eating food, such as pig liver?

Dr Chan said: “The safest way of consuming food, including pork, is to cook it thoroughly.”