Tests that found the deadly bird flu virus strain in nasal swabs from pigs in Vietnam are not reliable and do not mean that swine are involved in the outbreak ravaging Asian farms, U.N. officials said Friday. Two more people died of the disease, raising the death toll to 18.
A Vietnam representative of the U.N. Food and Agriculture Organization announced the test results early Friday in Hanoi, but experts at the agency’s headquarters in Rome later distanced themselves from the finding.
The officials said the tests cited in Vietnam “do not conform to the standards established” by the World Organization for Animal Health, Peter Roeder, an FAO veterinary virologist and animal health expert, said in a statement issued by the agency.
Also Friday, doctors in Vietnam announced two additional deaths from bird flu, a 6-year-old girl from southern Dong Nai province and a 24-year-old man from central Lam Dong province, raising the total in that country to 13. Five people have died from the virus in Thailand.
Scientists dismiss test results
Most human cases have been traced to direct contact with infected chickens. However, experts have said it’s possible the virus can jump to humans through another mammal, such as pigs. Pigs have been implicated in human flu epidemics in the past.
“Right now, there is no justification for saying there is H5N1 virus infection in pigs in Vietnam,” he said, referring to the lethal strain of avian influenza plaguing poultry across Asia.
The agency said it would not be surprising if sampling of nostrils of swine in any country affected by the outbreak led to detection of flu viruses in a small proportion of animals.
Swine are often housed with poultry in traditional family farms in Asia and are genetically more similar to humans than birds are. They eat off the ground and it’s possible they might inhale infected chicken droppings.
But finding the virus in the nostrils does not necessarily mean that the pig is infected, the agency said. Swab tests can easily be contaminated and are considered only to be a sign that further testing is needed. A more conclusive test would entail isolating the virus from blood samples of the pigs.
Other scientists have tested hundreds of pigs in Vietnam during the current outbreak, using internationally approved methods, and have found no trace of the virus, FAO said.
“There’s absolutely no data available that would indicate that swine are involved in what’s happening in this epidemic of avian influenza,” the agency said.
More than 50 million chickens slaughtered
Also Friday, health officials in eastern China were looking into a mass death of brambling finches, a migratory sparrow-like bird that winters throughout China.
Bird flu has ravaged poultry farms across Asia and is continuing to spread. More than 50 million chickens have been culled to stem the spread of the disease. Ten governments are battling outbreaks.
The U.N. food and agriculture agency on Thursday backed the strategic use of chicken vaccination to help reduce the economic toll while still protecting human health,
The destruction of infected birds remains the main method of fighting the disease, but officials worry that because the outbreak is so widespread, governments will not be able to afford to compensate farmers for the loss of their poultry and people will therefore resist killing their chickens, which increases the risk of the disease spreading.
Health officials have warned that if the bird flu virus combines with a human influenza virus, the result could create a more lethal strain that can be passed from human to human. There is no evidence that this has happened.