Emerging virus infects humans.

Emerging virus infects human

A marine virus that caused an epidemic among swine when it moved into land animals 53 years ago has for the first time made a human ill. If the virus, a member of the "calicivirus" family, follows the pattern the group has established in other species, the first human infection won't be the last.

Caliciviruses are known to cause a range of ills, from blisters to spontaneous abortion and encephalitis. Common among marine organisms from firsh parasites to whales, caliciviruses, if not always the diseases they cause, have also been identified in a wide range of land animals, from snakes to primates (SN: 8/30/80, p. 136).

Last December, Eugene Berry, a researcher at a calicivirus laborator at Oregon State University in Corvallis, developed the deep blisters characteristic of calicivirus infection. Though the virus caused no other symptoms and did not spread to Berry's family or colleagues, the lab reported the infection to health officials.

Human susceptibility was not unexpected. Anecdotal evidence and positive antibody tests pointed to a few earlier, undocumented infections in other researchers. And the range of hosts already identified is undeniable in its implication. "If you have a virus that has the capability to cross the species range like that, you don't hae to be really imaginative to think it'll move just one notch further," says Alvin Smith, head of the lab.

Caliciviruses were introduced into land animals in the 1930s, in first-containing garbage fed to pigs. In 1956, when the virus was eradicated from pigs, it was though to have ben eliminated from the world. It wasn't until a calicivirus was identified in California sea lions in 1972 that researchers realized the pig virus had come from the sea, and had retreated there.

There were no reported cases of human infection while pig farmers were in close contact with the virus, nor were there signs that the virus could spread to other animal species. The virus's newly evident ability to cross species boundries. Smith says, indicates it is in a period of change and expansion.

The ultimate import for human health is a matter of speculation. The human host may be a dead end for the virus, since out of a number of probable infections there have been no cases of human-to-human transmission. Or, following the pattern seen in other species, the virus may eventually take hold in humans. "All you can do is extrapolate," says Smith.