Oct 10, 2006 (CIDRAP News) – Pigs and stray cats have been found infected with the H5N1 avian influenza virus in Indonesia, adding to the few previous reports of such cases, according to news services.
A study from Udayana University found that two pigs on the island of Bali were infected with the H5N1 virus in July, senior agriculture minister Musni Suatmodjo told Reuters yesterday. According to news reports, veterinary faculty from the university discovered the infected pigs in Bali's south-central Gianyar and Tabanan regencies.
News reports didn't say if the pigs were sick or died.
Flu experts worry about H5N1 findings in pigs because the animals can carry human as well as avian influenza viruses, which presents the viruses an opportunity to combine and form new strains that could spark a human flu pandemic.
This isn't the first time that the H5N1 virus has been identified in Indonesian pigs. In 2005, a report in Nature said the virus was found in 5 of 10 healthy pigs kept near poultry farms in western Java where poultry were infected with H5N1. The report said the Indonesian government had found similar results among pigs in the same region.
The H5N1 virus was also found in pigs in China in 2001 and 2003, but follow-up surveys in 2004 found no evidence of the virus, according to the Nature article.
Meanwhile, researchers from the Indonesian Environment Information Center (PILI) in Yogyakarta announced that stray cats had caught the H5N1 virus from infected poultry at live markets, according to a report Oct 7 in the Jakarta Post. There were no details about the location of the stray cats or if they were sick or died.
"We are positive that cats can have the virus, although it is yet to be proven that they can transmit the virus to other animals or humans," said PILI director Iwan Setiawan.
Other instances of cats infected with the H5N1 virus have been documented: house cats in Germany, Thailand, and Austria, and a leopard and tigers at a zoo near Bangkok.
But the role of cats in transmitting the H5N1 virus is not known. The World Health Organization said earlier this year that no human cases have been linked to diseased cats. However, Albert Osterhaus, a virologist with the Erasmus Medical Center in the Netherlands, said that cat-to-human transmission is theoretically possible and that cat-to-cat transmission has been shown in a laboratory setting.
Meanwhile, in the United States, final tests showed that the flu virus found in wild northern pintail ducks in west-central Montana's Cascade County last month was an H5N3, a mild strain, not the deadly Asian strain of H5N1, the US Department of Agriculture (USDA) announced on Oct 7.
In September, investigators found the H5 and N1 virus subtypes in healthy ducks. The samples were sent to the USDA National Veterinary Services Laboratory (NVSL) in Ames, Iowa, where investigators found a low-pathogenic H5N3 virus in 2 of 16 samples.
The USDA said it's not unusual for a specific subtype to be identified in initial screening tests but not be isolated in confirmatory testing, because the screening tests are so sensitive. In this case, the N1 subtype was weakly identified as positive by rapid screening, but confirmatory testing instead found the N3 subtype. Previously announced genetic testing had already ruled out the presence of the highly pathogenic H5N1 strain.
Low-pathogenic avian flu viruses often occur naturally in wild birds and cause only minor sickness or no noticeable signs of disease. They pose no risk to human health. However, low-pathogenic strains sometimes mutate into deadly strains.
The testing of Montana ducks is part of an effort by the USDA and the Department of Interior to test wild birds throughout the United States for the deadly H5N1 avian flu. Previous tests on birds from Michigan, Maryland, and Pennsylvania have been positive only for the low pathogenic "North American" strain of H5N1.
USDA-DOI news release on avian flu in Montana ducks
Nature report on H5N1 virus in pigs in Indonesia
May 27, 2005 CIDRAP News article "Indonesian pigs have avian flu virus; bird cases double in China"