| HONG KONG
HONG KONG May 26 China may have unwittingly
introduced swine flu viruses when it imported pigs from Europe
and North America for breeding over the past few decades,
Three virus families are endemic in pigs in southern China
and one of them - the Eurasian avian-like H1N1 flu virus from
Europe - is viewed as most threatening because humans have no
antibodies against it, said the researchers, who published their
findings in Nature magazine on Thursday.
The researchers in Hong Kong, Singapore and China reached
their findings after monitoring swine flu viruses in pigs in
Hong Kong over a 12-year period.
"We found that since 2001, the Eurasian (flu) viruses and
North American viruses had entered pig populations in southern
China and replaced the earlier viruses," said Vijaykrishna
Dhanasekaran, assistant professor at the Duke-NUS Graduate
Medical School's Program of Emerging Infectious Diseases in
"The import of breeding pigs has increased in southern China
over the 20 years, this was done to improve the breeds," he said
by telephone from Singapore.
From 1998 to 2010, Dhanasekaran and colleagues collected
more than than 650 flu virus samples from pigs that ended up in
a Hong Kong abattoir and found they all belonged to three
The most dominant was the Eurasian avian-like H1N1 virus.
First detected in pigs in Belgium in 1979, it quickly became the
most common flu virus in pigs in Europe.
The other 2 lineages are the North American H1N2 swine flu
virus which has been circulating in pigs in North America since
the 1990s and the H1N1 swine flu virus which has been
circulating worldwide, including in China, for more than 80
VIRUSES RODE ON BREEDING PIGS
"The introduction could have most likely been the breeding
pigs ... Now we have a better understanding of how viruses
travel globally," said Dhanasekaran.
The Eurasian avian-like virus was potentially most
problematic because people do not have immunity, or antibodies,
to fight it, he said.
"We have this Eurasian avian-like H1N1 virus which we don't
have any antibodies (against) ... and it is likely that this
virus can spread among humans easily," he said.
He urged other regions to conduct similar disease
surveillance in animals.
"The diversity in other areas can be different and what they
should do is conduct surveillance and target viruses that we
don't have antibodies towards and these would most likely be
candidates for pandemic preparedness," Dhanasekaran said.
What experts fear are animal viruses new to people making a
jump to humans and sparking a pandemic. This was how the H5N1
bird flu virus and SARS spread around much of the world in 2003.
In 2009, a novel H1N1 swine flu virus caused a pandemic.
Eighty to 95 percent of pigs slaughtered in Hong Kong
originate in southern China, which has the largest swine
population in the world.
(Editing by Robert Birsel)
(Created by Ee-lyn Tan)