DVMs more vulnerable to HEV-positive pigs
Swine veterinarians have a marginally higher risk of contracting swine hepatitis E virus (HEV) than the general non-veterinary population, a recent study concludes.
"That's not surprising because of their occupational exposure," says Xiang-Jin Meng, M.D., Ph.D., who led a study in which scientists analyzed the risk to veterinarians of contracting swine HEV.
The study, published in the Journal of Clinical Microbiology (January 2002), assessed the potential risk of zoonotic HEV infection by testing 468 swine veterinarians (including 389 U.S. swine veterinarians who belonged to the American Association of Swine Practitioners). In addition 400 normal U.S. blood donors were tested for immunoglobulin G anti-HEV.
The veterinarians were tested from eight U.S. states (Minnesota, Indiana, Nebraska, Iowa, Illinois, Missouri, North Carolina, and Alabama) from which normal blood donor samples were available.
"These states were chosen because states like Minnesota and Iowa are the major swine-producing states. We also included Alabama (which) is traditionally a non-swine producing state to see if there was a difference between a major swine state and non-swine state," says Meng, who discovered the swine version of human hepatitis E in 1997.
At the time of discovery, Meng says, "We did not know whether the pig virus would cause any disease or even affect humans at that time. " In the past five years, researchers confirmed the virus is zoonotic.
Testing blood samples
In the most recent study, Meng and team used recombinant capsid antigens from a U.S. strain of swine HEV and from a human HEV strain (Sar-55) in an enzyme-linked immunosorbent assay.
The results: 26 percent of veterinarians were positive with Sar-55 antigen and 23 percent were positive with swine HEV antigen. In contrast, 18 percent of the blood donors from the eight states were positive with Sar-55 antigen and 17 percent were positive with swine HEV antigen.
In Minnesota, 44 percent of swine veterinarians tested positive for swine HEV; Iowa, 29 percent positive; while Alabama had only 13 percent.
Overall, scientists concluded that swine veterinarians in the eight states were 1.51 times more likely when tested with swine HEV antigen and 1.46 times more likely when tested with Sar-55 antigen to be anti-HEV positive than normal blood donors.
No difference was noted in anti-HEV prevalence between veterinarians who reported having had a needle stick or cut and those who had not or between those who spent more time and those who spent less time working with pigs.
Additionally, says Meng, "This disease is usually is age-dependent for swine and humans. The older you are, the more chance you get infected. However in this case, we found that age is not a factor in observed differences from state to state."
The next step is to develop a first-ever vaccine, says Meng. The National Institutes of Health is supporting two grants for such a project. Meng envisions a vaccine based on the swine HEV virus to prevent human disease, "the so-called generic approach. We'll try to use a pig virus to try to prevent a human hepatitis E virus."
In the meantime, "The best precaution a veterinarian should take is to wash their hands thoroughly when they handle pigs. This is a fecal orally transmitted disease. If you touch pigs' feces-contaminated water or water supplies and you don't wash the hands before drinking or eating, you probably can get infected," he says.
"Washing hands and practicing hygiene is the No. 1 preventive measure for this disease."