North Carolina has become the fourth state with confirmed cases of novel H1N1 flu in pigs.

A federal laboratory has verified the presence of the 2009 novel H1N1 flu virus in samples taken from pigs at two North Carolina farms. Minnesota, Indiana and Illinois have previously reported cases of the novel H1N1 virus in pigs.

The pigs in North Carolina have been under the care of a swine veterinarian and have recovered from the illness. “The herd veterinarian noticed signs of mild illness in the pigs and conducted tests to determine the type,” reports State Veterinarian David Marshall. “Confirmatory tests by the U.S. Department of Agriculture’s National Veterinary Services Laboratory in Ames, IA, indicated the virus was H1N1.

“Pigs are subject to flu viruses just like humans, so it’s not unexpected to find it in a herd,” Marshall says. “These cases show that our surveillance system is working.”

Tom Ray, DVM, director of livestock health at the North Carolina Department of Agriculture and Consumer Services, says it appears that the pigs at both farms caught the H1N1 virus from humans. The herd owners reported workers in contact with the animals had shown flu-like symptoms days before the animals came down with the illness.

A new study conducted by the U.S. Department of Agriculture (USDA) scientists provides additional confirmation that the meat and tissue from pigs exposed to two strains of the 2009 novel pandemic H1N1 virus did not contain virus. The study was conducted at USDA’s Agricultural Research Service (ARS) at the National Animal Disease Center in Ames, IA.

“This research provides additional reassurances for consumers about the safety of pork,” says Edward B. Knipling, ARS administrator. “The information contained in the study will also benefit customers of U.S. pork products, both here and abroad.”

Researchers inoculated a group of 30, five-week-old pigs with the virus and five pigs not inoculated served as controls. The pigs were observed daily for clinical signs and then were euthanized at three, five or seven days after inoculation.

Researchers tested tissue samples of the pigs’ lungs, liver, muscle, spleen and other vital organs to detect for the presence of the virus. The inoculated animals showed signs of upper respiratory disease indicative of flu, but no evidence that the virus had spread to any other parts of the body.

These findings support recommendations from the World Health Organization that pork from infected swine that recovered from the virus can be safely handled or eaten, following basic hygiene practices for handling of meat.

The virus has also been identified in cats in Iowa, Oregon and Pennsylvania; ferrets in Oregon; turkeys in Virginia; a dog in New York and a cheetah in California. In all these cases, it appears the animals caught the virus from humans.