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 analyzedthe risk to veterinarians of contracting swine HEV.

The study, published in the Journal of Clinical Microbiology (January2002), assessed the potential risk of zoonotic HEV infection by testing468 swine veterinarians (including 389 U.S. swine veterinarians who belongedto the American Association of Swine Practitioners). In addition 400 normalU.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 whichnormal blood donor samples were available.

"These states were chosen because states like Minnesota and Iowaare the major swine-producing states. We also included Alabama (which) istraditionally a non-swine producing state to see if there was a differencebetween a major swine state and non-swine state," says Meng, who discoveredthe swine version of human hepatitis E in 1997.

At the time of discovery, Meng says, "We did not know whether thepig 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 antigensfrom a U.S. strain of swine HEV and from a human HEV strain (Sar-55) inan enzyme-linked immunosorbent assay.

The results: 26 percent of veterinarians were positive with Sar-55 antigenand 23 percent were positive with swine HEV antigen. In contrast, 18 percentof the blood donors from the eight states were positive with Sar-55 antigenand 17 percent were positive with swine HEV antigen.

In Minnesota, 44 percent of swine veterinarians tested positive for swineHEV; Iowa, 29 percent positive; while Alabama had only 13 percent.

Overall, scientists concluded that swine veterinarians in the eight stateswere 1.51 times more likely when tested with swine HEV antigen and 1.46times more likely when tested with Sar-55 antigen to be anti-HEV positivethan normal blood donors.

No difference was noted in anti-HEV prevalence between veterinarianswho reported having had a needle stick or cut and those who had not or betweenthose who spent more time and those who spent less time working with pigs.

Additionally, says Meng, "This disease is usually is age-dependentfor 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 differencesfrom state to state."

The next step is to develop a first-ever vaccine, says Meng. The NationalInstitutes of Health is supporting two grants for such a project. Meng envisionsa vaccine based on the swine HEV virus to prevent human disease, "theso-called generic approach. We'll try to use a pig virus to try to preventa human hepatitis E virus."

Advice

In the meantime, "The best precaution a veterinarian should takeis to wash their hands thoroughly when they handle pigs. This is a fecalorally transmitted disease. If you touch pigs' feces-contaminated wateror 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 measurefor this disease."