Scientists have warned consumers to thoroughly cook meat from pigs after finding the hepatitis E virus in pork sold in Cape Town.
Hepatitis E causes jaundice, loss of appetite and nausea. In rare cases it can cause acute liver failure, particularly in pregnant women and patients with a comprised immune system.
The virus is usually transmitted through drinking water contaminated with faeces, but scientists who bought 144 food samples from supermarkets and butcheries around Cape Town found it in two liver spreads.
Stephen Korsman, of the National Health Laboratory Service, said the spreads came from two different supermarket chains in 2014. They were among five samples of liver spread tested.
Reporting his findings in the August edition of the SA Medical Journal, Korsman said more than one in four Western Cape residents had hepatitis E antibodies, and the study had pointed to a “plausible infective source”.
The virus had been identified in pigs in the Western Cape and Eastern Cape, he said, and was common in pigs in industrialised countries.
“The risk of contracting the virus by way of pork products is higher when consuming undercooked or raw [meat],” he said.
“Cooking at 71ºC for 20 minutes has been found to fully inactivate the virus.”
Korsman and colleagues from the University of Cape Town said there were other possible sources of hepatitis E that could explain the high level of antibodies in the Western Cape population.
“A possible reservoir not yet studied locally could be filter-feeding shellfish, as they feed on sewage entering the ocean. Such shellfish are regularly eaten in Cape Town,” said the report.
“Further potential sources of hepatitis E … may include seafood and raw vegetables.”
Peter Evans, head of consumer assurance at the SA Pork Producers Association, said it had supported the 2014 research, and “any potential food safety issues will always be investigated”.
Hepatitis E was found in pigs all over the world. “It was thus not a surprise that there was a high level of sero-prevalence in pigs in the study done,” he said.
“Many factors contribute to infection developing in pigs and the prevalence found between different populations of pigs.”
However, as pigs occasionally developed mild symptoms of disease, “it would be difficult for farmers to know without doing serological test that pigs had contracted [hepatitis E]. The disease in pigs is self-limiting”.
Evans said modern farms that used properly drained housing with floors that could be thoroughly cleaned reduced the risk of pigs becoming infected or staying infected.
“Encouraging farmers to adopt modern farming practices is thus a means of ensuring food safety (as compared to outdoor systems),” he said.
Assurance programmes used in the pork industry included guidelines on biosecurity, hygiene, pest control, water quality, manure/wastewater management and employee health. “All these measures help reduce risk of infections in pigs,” he said.
Evans agreed with the researchers led by Stephen Korsman, of the National Health Laboratory Service, who said there were many other potential sources of hepatitis E..
“Vegetables, fruits and other plant-based foods can be potentially contaminated through contaminated irrigation water. There is also a possibility that shellfish harvested of our coasts that are in sewage discharge areas may also become infected,” he said.
The pork industry was aware of potential transmission if infected pork was consumed, but the association was concerned that Korsman’s team did not investigate other possible transmission pathways.
“I’m also not clear on whether there is a direct link to the liver spread that tested positive and pigs in the Western Cape. The origin and type of liver spread is not mentioned.
“SA imports a reasonable amount of pork into the country and pork products produced in SA are distributed widely. Unfortunately, there are too many gaps in the chain between farm and retail shelf to be sure that the link is complete.”
Pork association CEO Johann Kotzé said the reasearchers’ warning that meat should be thoroughly cooked “created the impression that pork meat is not safe. How do you cook a liver spread – the only product where they found hepatitis E?”
Kotzé said the industry suffered “a rough 18 months” after the listeriosis outbreak and “still battles the current negative foot-and-mouth disease and African swine fever reporting”.