AUG 05, 2017 3:34 PM PDT

Gauging the Threat Posed by Hepatitis E

WRITTEN BY: Carmen Leitch

There are several types of hepatitis, and while you’ve likely heard of A, B, and C, researchers are trying to draw attention to hepatitis E (HEV), which gets far less attention. Worldwide, it is actually the biggest cause of acute viral hepatitis. While the illness often gets better after a few weeks, it can cause liver failure, a fatal disorder. While it was once seen a problem that came with poor sanitation and a lack of clean water, that is changing.

Electron micrograph of Hepatitis E viruses (HEV) / Credit: CDC Public Health Image Library

Often spread by fecal contamination, HEV was once a disease of the impoverished. Now it is starting to impact more affluent people in modernized environments. Often carried by travelers returning from regions stricken with the virus, it is now being contracted through contaminated meat in places like France and the UK. HEV has been detected at varying levels in samples of pig feces and meat, although one study found HEV in 10% of retail sausage samples in the UK; research in Europe and the US have reached similar conclusions. Studies have indicated that thorough cooking probably eliminates all of the viral particles.

Dr. Tongai Maponga works with the Division of Medical Virology at Stellenbosch University (SU) as a postdoctoral researcher who studies HEV. In his research with investigators at the University of Cape Town, 16 commercial pig herds supplying pork to Cape Town were assessed. They found that animals on every farm were infected or had been exposed to HEV.

"If some of our pigs have HEV, there's the risk pork consumers might get infected. We're not saying people shouldn't eat pork, but farmers must look after the pigs and ensure these viruses don't end up in the food supply," said Maponga. “They must also prevent environmental contamination: you don't want sewage runoff from piggeries entering water sources. This would be a worry in poorer areas, where people might get drinking water from the river."

Many animals can host HEV, and it is suspected that seafood can harbor the virus as well. One aspect of ongoing research is identifying all potential hosts. This disease could eventually become a serious threat.

Maponga works among a research group at SU that characterized chronic HEV infection in an HIV-infected patient in South Africa for the first time.

"HEV has the potential to become a chronic infection, especially in immunosuppressed patients. This is a risk in South Africa, where there are many HIV-infected patients. We described the first HIV patient with chronic HEV in 2012. After starting antiretroviral therapy, he had elevated liver enzymes (which indicates liver disease). More obvious potential causes for this were considered; it was only after about a year that we thought to test for HEV,” explained Maponga.

"Also interesting was the HEV genotype (genetic variant) present. Hepatitis E as a disease of the poor is normally associated with genotypes one and two, but this patient was infected with genotype three, which is also the genotype that circulates in pigs, thus indicating zoonotic transmission,” he continued. In other words, people were found to be infected with the viral type normally carried by pigs, indicating they'd gotten their illness from an animal.

"We've subsequently seen about four more cases of HEV infection. This may seem a small number but it could mean the problem is becoming more prevalent in the larger community."

Chronic HEV infection is also a risk for transplant recipients, due to the immunosuppressant therapy they receive as part of their treatment. This research group also identified an HEV case in a kidney transplant recipient for the first time.

"Before transplant operations, patients are screened for the obvious hepatitis viruses like B and C, but people tend not to consider HEV, so it can go undiagnosed and unsuspected. There are now several other cases described in the literature. In one study in Asia, a liver transplant patient with continuously elevated liver enzymes was found to have picked up HEV from a camel,” noted Maponga.

The scientists have also been checking the blood supply in their region, looking for HEV in blood donors. "We found antibodies that showed some donors had been exposed to HEV," revealed Maponga, "but thankfully we didn't see the actual viral nucleic acids or the antigen that would indicate they are infected."

Learn more about hepatitis E from the video.

Sources: AAAS/Eurekalert! Via Stellenbosch University, Food Safety Authority of Ireland

About the Author
BS
Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
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