New Bird Flu Virus Replacing Other Strains in Southern China

By Cheryl Pellerin
Washington File Staff Writer

Washington - A new variant of the highly pathogenic H5N1 bird flu virus, the Fujian-like strain, has replaced most other strains across a large part of southern China since 2005 despite mass poultry vaccinations, according to researchers at the University of Hong Kong and St. Jude Children’s Research Hospital in Tennessee.

The work was supported in part by the U.S. National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, and the Li Ka Shing Foundation, a Chinese organization that supports education and medical care.

The Fujian strain has been known in southern China and Southeast Asia since 2003, but scientists have seen an increased occurrence of the virus since 2005.

The strain might be responsible for an increased number of H5N1 poultry infections since October 2005 and for the recent human cases in China, the study said. The strain has been transmitted to Hong Kong, Laos, Malaysia and Thailand, causing a new bird flu outbreak wave in Southeast Asia that also has caused human infections.

In 2005, the World Health Organization (WHO) confirmed 95 human cases of avian influenza in five countries; in the first eight months of 2006, WHO confirmed 96 human cases in nine countries.

“The Fujian virus doesn’t appear to be of any more risk to humans,” Dr. Michael Perdue, project leader for avian influenza in the Global Influenza Programme at the World Health Organization, told the Washington File November 2, “other than the fact that maybe it’s a little more widespread and it seems to be supplanting the other strains in the region.”

As far as scientists know, he added, “there’s no increased – or decreased – likelihood of human transmission. It’s basically the same overall genetic content of the other H5N1 viruses.”


Worldwide, the seventh human death in Egypt from H5N1 avian flu, confirmed by the Ministry of Health October 31, brings the total number of human cases to 256, with 152 deaths.

China's Health Ministry has sent samples of the human strains of H5N1 to the WHO for distribution to scientists around the world for study, but its Ministry of Agriculture has not sent samples from birds since 2004.

“Our country office in Beijing has been trying for the last two years,” Perdue said, “to get samples of viruses that are circulating in animals in China sent to the WHO collaborating centers so we can put them in our archives of H5N1 viruses for diagnostics and vaccine development.”

According to news reports, WHO has criticized China’s Agriculture Ministry for complicating efforts to learn about the virus and to understand the implications of its spread in southern China and Southeast Asia.


The U.S.-Chinese researchers studied live-poultry markets in six provinces of southern China from July 2005 to June 2006, finding that 1,294 of 53,220 birds were H5N1 positive, mainly ducks and geese, an increase from the 2004-2005 period.

Since November 2005, some 22 human cases have been confirmed in 14 Chinese provinces, and some of these victims lived in metropolitan areas far from poultry farms.

“Whether those people were infected locally and directly from affected poultry or other sources, including humans,” the study said, “is still unknown.”

According to the study, “Emergence and predominance of an H5N1 influenza variant in China,” in the November online edition of the Proceedings of the National Academy of Sciences, H5N1 influenza virus caused poultry outbreaks in China in 12 provinces from October 2005 to August 2006 despite a compulsory poultry vaccination program that began in September 2005.

The emergence and rapid distribution of the Fujian strain, despite the vaccination program that began in September 2005, suggests that H5N1 control measures are inadequate, said study co-author Robert Webster, a member of the St. Jude Infectious Diseases Department, in a statement.

“Given the lack of systematic influenza surveillance in poultry at a national level,” the authors wrote, “the timely identification of the source of human infection is almost impossible.”

Comprehensive influenza surveillance in humans and animals is urgently required in H5N1-affected regions, the authors added, and it is critical that similar surveillance programs begin in Indonesia, Vietnam, Thailand and India.

“Perhaps most importantly,” they said, “information from northern China is required because it could answer key questions regarding the movement of H5N1 in and out of southern China, the hypothetical influenza epicenter.”

For ongoing coverage of this disease and efforts to combat it, see Bird Flu (Avian Influenza).