Effects of H1N1 in pigs studied
2009-05-12 10:13
London - Thai scientists who infected
piglets with the new H1N1 virus spreading around the world said
on Monday 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.
Complex mix
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
infection 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.
Lung lesions
They also developed lung lesions large enough to
be seen by the naked eye.
The lesions were characterised 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.