*Plagues, Pestilences and Diseases

New H5N1 strain could start wave of bird flu outbreaks*

30 Oct 2006 21:01:57 GMT
Source: Reuters

By Tan Ee Lyn

HONG KONG, Oct 31 (Reuters) - Scientists in Hong Kong and the United
States have detected a new strain of H5N1 bird flu virus in China and
warned it might have started another wave of outbreaks in poultry in
Southeast Asia and move deeper into Eurasia.

The strain, called the "Fujian-like virus" because it was first isolated
in China's southern Fujian province in March 2005, has increasingly been
detected since Oct. 2005 in poultry in six provinces in China,
displacing other H5N1 strains.

The strain might also have become resistant to vaccines, which China
began using on a large scale from Sept. 2005 to protect poultry from
H5N1, said the scientists.

The researchers are from the University of Hong Kong, including
virologists Guan Yi and Malik Peiris, and Rob Webster of St Jude
Children's Research Hospital in the United States.

"The predominance of this Fujian-like virus appears to be responsible
for the increased prevalence of H5N1 in poultry since Oct. 2005 and
recent human infection cases in China," they said in an article
published in the U.S.-based Proceedings of the National Academy of
Sciences (www.pnas.org).

"It has already caused poultry outbreaks in Laos, Malaysia and Thailand,
and human disease in Thailand. It is likely that this variant has
already initiated a third wave of transmission throughout Southeast Asia
and may spread further in Eurasia."

The first wave of H5N1 outbreaks occurred in late 2003 and 2004 in many
parts of Asia. The second wave started in China's Qinghai Lake in May
2005 and that strain has since been found in parts of Europe, Africa and
the Middle East.

The virus has killed more than 150 people since late 2003 and remains
largely a disease among birds. But experts fear it could trigger a flu
pandemic and kill millions of people if it mutates into a strain that
can pass from human to human.

SUPER STRAIN

The researchers collected 53,220 fecal samples from chickens, geese and
ducks in poultry markets in six Chinese provinces between July 2005 and
June 2006. Of these, 1,294 tested positive for H5N1.

But genetic sequencing of viruses collected from Oct. 2005 onwards
showed the Fujian strain was clearly becoming predominant over other
H5N1 strains. Between April and June this year, 103 out of 108
H5N1-positive samples were of the Fujian type.

"That's pretty conclusive proof that this new variant is predominant,"
said Gavin Smith, one of the researchers in the Hong Kong team.

To test how well vaccinated poultry could stand up to various strains of
H5N1, the researchers collected 1,113 blood samples from chickens from
Nov. 2005 to April 2006.

Only 180 samples, or 16 percent, tested positive for H5N1 antibodies.
They were exposed to 3 strains of H5N1 -- namely the Yunnan, Guiyang and
Fujian-like strains.

The antibodies managed to neutralise the Yunnan and Guiyang strains, but
had little or no effect on the Fujian virus.

"The market poultry, many of them don't have antibodies against H5 virus
and those that do are not well protected against the Fujian virus, which
is why we think the Fujian-like virus has been able to grow because
other (strains) have been suppressed," Smith told Reuters in an interview.

"What happens with vaccines is that you basically introduce something
that kills off most of the viruses, but there are always going to be
some viruses that can escape from it."