One in 10 sausages and processed pork meat products in England and Wales could cause hepatitis E virus (HEV) infection if undercooked, experts warn.
There has been an “abrupt rise” in the number of cases in England and Wales as people do not realise the risk, scientists advising the government say.
Sausages should be cooked for 20 minutes at 70C to kill the virus, they said.
Although serious cases are rare, HEV can cause liver damage or be fatal.
Official government figures show there were 124 confirmed cases of HEV in 2003, which rose to 691 cases in 2013. There were 461 cases in the first six months of this year.
Symptoms include jaundice and sometimes tiredness, fever, nausea, vomiting and abdominal pain.
Most people will get over the virus, although for some, such as those with an immune deficiency disorder, or pregnant women, it can prove fatal.