China's southern Guangdong Province found to be source of H5N1

A team of scientists at the University of California, Irvine, who have been conducting a genetic analysis of the H5N1 bird flu virus, have found that China's southern Guangdong Province is the source of the deadly strain.

The researchers say the multiple H5N1 strains spreading at both regional and international levels originated in the Chinese province of Guangdong, which also appears to be the source of renewed waves of the H5N1 strain.

Walter Fitch, a professor of ecology and evolutionary biology who worked on the study, has reportedly said the virus is probably still originating there and still spreading.

Fitch says if the virus is controlled at its source, it can be controlled more efficiently, and a 'road map' of where the strain has migrated, will make it easier to isolate the strain that is needed to make a vaccine.

Since 2003, H5N1 has spread globally and reached more than 50 countries as far away from China as Nigeria and Britain.

It has to date killed or forced the destruction of hundreds of millions of birds and killed 167 people.

The fear gripping scientists is that the virus will mutate into a form that can easily pass from person to person triggering a pandemic which could kill billions.

Fitch's team examined samples of the virus taken from across China and as far west as Russia and also looked at the genetic sequences of virus samples placed in GenBank, a public access database of genetic information.

They were able to construct a "family tree" for the virus, which mutates quickly by looking specifically at two proteins, called hemagglutinin and neuraminidase, the "H" and "N" in a flu strain's name.

Their results show the basic version of the virus is a form seen in Guangdong over and over again.

Robert Wallace, a postdoctoral researcher who led the study says the virus appears to be seeding multiple outbreaks both from within China and elsewhere and China is the primary epicenter.

Wallace says secondary epicenters now exist as well, that have 'caught on fire'.

The researchers say their maps show China's northwest Qinghai Province to be another source of bird flu's spread.

Wallace says the study has practical value, as neighboring countries can carefully watch imports from southern China and can make bird vaccines that match the Chinese strain of H5N1.

Meanwhile the Chinese can investigate what is going on in Guangdong and if their poultry there contributes to those strains, they could intervene.

The researchers found in contrast that Thailand, Cambodia and Vietnam appeared to absorb strains of the virus and while H5N1 spreads there it does not spread to anywhere else.

Fitch and Wallace say the study demonstrates why it is important for countries to share samples of the virus from within their borders with the scientific community.

Meanwhile a major state-run Chinese newspaper has denied Guangdong province to be the source of the deadly virus.

The China Daily has quoted He Xia, a Guangdong agricultural official, as saying the wrong conclusion has been reached and the study 'lacks credibility'.

Last week a woman farmer in southeast Fujian province was confirmed as China's 23rd human case of bird flu.

China has the world's largest poultry population with millions of backyard birds roaming free.

The report is published in the Proceedings of the National Academy of Sciences.