Hepatitis E Virus Could Become a Concern Among Developed Countries

HEV is reemerging as a zoonotic virus, with individuals becoming infected via pigs and pork products.

Hepatitis E virus (HEV) outbreaks are frequently associated with undeveloped countries with poor sanitation and a lack of access to clean water; however, new study findings indicate a shift in which HEV has begun to affect affluent individuals in developed countries.

Although HEV can usually be cleared within a few months, it can sometimes cause acute liver failure. It is typically spread through the fecal oral-route, but in developed countries is reemerging as a zoonotic virus.

In countries such as France and the United Kingdom, individuals are acquiring the infection from pigs and pork products.

Dr Tongai Maponga is particularly interested in viral hepatitis, and was part of a group of investigators who identified the first case of chronic HEV in a South African patient who was HIV-positive.

“HEV has the potential to become a chronic infection, especially in immunosuppressed patients,” Maponga said. “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. More obvious potential causes for this were considered; it was only after about a year that we thought to test for HEV. Also interesting was the HEV genotype present. Hepatitis E as a disease of the poor is normally associated with genotypes 1 and 2, but this patient was infected with genotype 3, which is also the genotype that circulates in pigs, thus indicating zoonotic transmission.”

Maponga said that there have been 4 additional cases of HEV infection, which suggests it is becoming more prevalent in the larger community.

Transplant patients are also at risk for chronic infection because they undergo immunosuppressive therapy, the authors noted. In 2015, a kidney transplant patient became infected with HEV genotype 3 months after transplantation.

“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,” Maponga said. “There are 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.”

In a more recent study published in early 2017, the investigators examined HEV infection among blood donors in the Western Cape.

“We found antibodies that showed some donors had been exposed to HEV, but thankfully we didn’t see the actually viral nucleic acids or the antigen that would indicate they are infected,” Maponga said.

The investigators hypothesized that the seroprevalence of HEV and hepatitis A virus would mirror each other because they both spread via the fecal-oral route. Instead, the results of the study showed the prevalence differed, with HEV prevalence being lower. Furthermore, HEV seroprevalence differed by race groups, with the highest in mixed race donors and the lowest in black donors.

The investigators tested 16 commercial pig herds that supplied pork to Cape Town during the current study. They found evidence that animals on all the tested farms had been exposed to, or infected with, HEV.

“If some of our pigs have HEV there’s the risk pork consumers might get infected,” Maponga said. “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. 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.”

Meat derived from wild boar and other game may also be infected with HEV; however, the range of potential hosts is unclear and should be an important area to research in the HEV landscape.