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Hepatitis E (HEV), the most common cause of acute viral hepatitis worldwide, has become zoonotic and has been transmitted to humans by pigs and, in one Asian case, by a camel. This raises a variety of public health concerns and will require a new set of safety precautions for livestock businesses that must be enforced by local governments. HEV infections usually resolve within weeks, but they can cause acute liver failure that leads to death. HEV has always been considered a human pathogen spread through the fecal-oral route and, up to this point, it primarily affected people who did not have access to clean water and good sanitation. Now people in the UK and France have contracted it from pigs and pork products, and experts think there is a risk that it could mutate and become a chronic infection, especially in immunosuppressed patients. Dr. Tongai Maponga and his colleagues at Stellenbosch University in South Africa described the first HIV patient with chronic HEV in 2012. The patient started antiretroviral therapy but his elevated liver enzymes prompted the team to do more tests, although it took a year for them to think of testing for HEV. HEV that is spread through poor sanitation and dirty water is either genotype 1 or 2, but Dr. Maponga’s patient had genotype 3, which is associated with pigs, indicating that the disease can now be transmitted to humans from animals. The team has since seen four other cases of HEV and they are worried because the number of immunosuppressed HIV patients in South Africa is large. Immunosuppressed transplant patients are also at risk. Maponga said that patients are screened for hepatitis B and C before surgery, but since clinicians do not think about testing for HEV, it can go undetected. He added that there are now several cases of HEV in transplant patients described in the literature, including the Asian liver transplant patient who acquired HIV from his camel. A 2017 study looked at HEV infections in blood donors in the Western Cape of Africa, and Maponga said only antibodies that indicated exposure were found, not viral nucleic acids or antigens that would indicate HEV infections. HEV exposure was highest in mixed race donors and lowest in black donors, but the reason for these results has not been determined. The Stellenbosch team collaborated with researchers at the University of Cape Town to test 16 commercial pig herds that supply Cape Town’s pork, and found evidence of HEV exposure and HEV infection in all of them. “If some of our pigs have HEV, there’s the risk pork consumers might get infected,” said Maponga. “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.” HEV does not only choose pigs as hosts. Wild boars, other game animals, and seafood may also carry the virus, so identifying the range of possible hosts is the next step in HEV research. World Hepatitis Day is observed on July 28 around the world.
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发表于 2017-8-2 10:18:38
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