China's leading bird flu experts yesterday refuted a report
printed in a foreign publication that a new strain of bird flu had
emerged in the south of the country and widely cited by foreign
media recently.
Scientists in Hong Kong and the United States said in a report
released last week that a new strain of bird flu called the
"Fujian-like virus," first isolated in the southern Chinese
province of Fujian last year, had become prevalent in the
Hong Kong Special Administrative Region, Laos, Malaysia, and
Thailand.
Chen Hualan, director of the National Bird Flu Reference
Laboratory at the Chinese Academy of Agricultural Sciences, rebuked
the report, published in the US-based Proceedings of the National
Academy of Sciences, saying its claims "lack scientific proof."
"The so-called 'Fujian-like virus' is not a new variant of the
virus," she said. "Gene sequence analysis of the virus shows that
it shares high conformity with the H5N1 virus that was isolated in
Hunan when bird flu broke out in early
2004."
Samples from every domestic bird flu outbreaks are sent for
isolation and gene sequence analysis at Chen's lab. She said that
in 2005 and 2006 the lab had isolated some viruses in waterfowl in
southern China which was reported to the Food and Agriculture
Organization (FAO) and the World Organization for Animal Health
(OIE).
"These viruses all remain steady in gene type and there is no
marked change in their biological characteristics," she said.
Chen said there was only one new variant of the virus which was
isolated in north China's Shanxi Province and the Ningxia Hui Autonomous
Region at the beginning of this year and had been reported to FAO
and OIE.
Experimental results show that the variant is weak in triggering
disease in mammals and a new vaccine, which has been put into use
in these areas, had effectively brought it under control.
Chen also defended the effectiveness of China's bird flu vaccine
saying that it had a "good effect," in response to the report's
surmise that the current vaccine was less effective for the
"Fujian-like virus."
The report claimed that through the analysis of serum samples
from 76 chickens for signs of antibodies against three H5N1
variants, including the Fujian-like strain, they found almost all
of them displayed two to four times more antibodies to the other
two variants than to the Fujian virus, suggesting that the vaccine
administered to the chickens was less effective against that
strain.
Chen said the evaluation of the vaccine was "not scientific" as
where the chickens were from and whether they had been vaccinated
was unknown.
Statistics from the Ministry of Agriculture showed that more
than 95 percent of domestic poultry had been vaccinated between
January and October.
Shu Yuelong, director of the National Influenza Centre at the
Chinese Centre for Disease Control and Prevention, also refuted the
report's allegation that five people in southern China were
actually infected by the new "Fujian-like virus."
Shu said that altogether 16 variants of bird flu viruses had
been found in the 20 confirmed cases of human infections on the
Chinese mainland since October 2005--seven in 2005 and 13 in 2006.
"Fifteen out of the 16 variants were isolated from cases in
southern China and they belong to the same gene type," Shu said.
"There's no proof that five of them were infected by a new mutated
virus."
(China Daily November 6, 2006)