Thai scientists who infected piglets with the new H1N1 virus spreading around the world said May 11 the strain caused flu-like symptoms in the animals before disappearing, just like many of the human cases.
An outbreak of the new strain, known as swine flu, that has killed at least 53 people – mainly in Mexico – has prompted some countries to ban pork from countries reporting human cases, even though officials have said there is no risk of spreading the virus by eating pork.
However, some pork producers are unsure how the virus could affect their animals.
The 22 piglets infected with the new virus showed flu-like symptoms between one and four days after infection and were shedding virus – meaning they could spread it – two days after infection, the researchers said.
None of the animals, also infected with the less dangerous H3N2 subtype, died, Roongroje Thanawongnuwech and colleagues from Chulalongkorn University in Bangkok reported.
“The results of this study may assist in the prevention and control of swine influenza virus in Thailand,” the researchers wrote in BioMed Central’s Virology Journal.
The new virus is a complex mix of swine viruses with avian and human bits, though nobody knows exactly where the new infect ion that first emerged in Mexico originated.
Influenza viruses mutate constantly and they also swap genetic material with one another promiscuously, especially if an animal or person is infected with two strains at once.
The team found that all infected pigs developed respiratory symptoms such as nasal discharge, coughing, sneezing and conjunctivitis. They also developed lung lesions large enough to be seen by the naked eye.
The lesions were characterized by dark plum-coloured, areas on the lung and were most severe two days after infection. This was especially the case in the H1N1-infected pigs, where about a third of the lung was covered.
“The results demonstrated that both swine flu subtypes were able to induce flu-like symptoms and lung lesions in weanling pigs. However the severity of the disease with regard to both gross and microscopic lung lesions was greater in the H1N1-infected pigs,” Thanawongnuwech said in a statement.