Ebola may have passed from a pig to a human

Ebola may have passed from a pig to a human<!--sizec--><!--/sizec-->



By Donald G. Mcneil Jr.
Friday, January 23, 2009

In <!--coloro:#8B0000--><!--/coloro-->the first known case of what may be transmission of the Ebola virus from a pig to a human<!--colorc--><!--/colorc-->, a pig handler in the Philippines has tested positive for a strain of the virus, world health officials and the Philippine government announced Friday.

But the strain ? Ebola Reston ? is not known to be dangerous to humans, and the worker, who was infected at least six months ago, is healthy, officials said.

<!--coloro:#8B0000--><!--/coloro-->The development is worrying because pigs are mixing vessels in which other viruses from humans and animals exchange genetic material, possibly creating strains that are more lethal or more infectious.<!--colorc--><!--/colorc-->

But Dr. Juan Lubroth, chief of animal health at the United Nations Food and Agricultural Organization, said there was "more need to investigate than to worry" and still many unanswered questions.

Ebola Reston, normally a monkey virus, was first found in pigs last year in the Philippines. Health authorities closed two farms and took blood samples from 6,000 pigs and 50 workers on the farms and in slaughterhouses. Only four pigs and the one worker tested positive, the Philippine health secretary, Francisco Duque, said at a news conference in Manila.

Dr. Lubroth said the first pigs tested were very sick, but turned out to have more than one infection, including a virulent reproductive and respiratory syndrome. ,The Ebola Reston may not have been what sickened them.

"But farmers, of course, would prefer to have pigs without Ebola," he said. "So we want to do more testing to see what they can do to protect them."

Broader sampling will determine, among other things, whether the disease is more common in pigs and humans than was known, whether it causes fever and how long its incubation period is.

Ebola Reston was first found in monkeys from the Philippines that died after arriving at a laboratory in Reston, Virginia, in 1989. Antibodies to it were found in workers in several laboratories, but it is not known to have caused more than a mild flu in any human.

<!--coloro:#8B0000--><!--/coloro-->By contrast, the Zaire, Sudan and Bundibugyo strains of Ebola, all found in African apes, cause fatal hemorrhagic fever in humans.<!--colorc--><!--/colorc-->

It is not known how the pigs were infected, but Dr. Lubroth noted that studies in Africa found Ebola viruses in fruit bats. Similar bats live in the Philippines, and fruit bats are thought to have transmitted Nipah virus to pigs, possibly through their droppings or dead bodies.