WHO: Bird flu continues to be public health threat in China as new case reported in military

China's latest reported case of bird flu _ a soldier _ has left questions about how he contracted the virus and shows that the disease remains a public health threat, the World Health Organization said Monday.

China's Health Ministry announced Saturday that the 19-year-old soldier who was hospitalized May 14 with a fever and a cough had contracted the H5N1 bird flu.

The announcement did not further identify the soldier or how he might have contracted the disease _ questions the WHO said it was pressing the Health Ministry to answer.

The virus is most commonly passed from sick poultry to humans who have close contact with the infected birds. Though it is assumed that's how the soldier contracted the virus, Henk Bekedam, the WHO's representative in China, said the case was China's 24th of 25 human infections that occurred without a reported outbreak among poultry.

"That is not a good record. I have to say that is still confirming that in China the animal surveillance system needs to be strengthened because this human case is a very clear reflection that the virus is still circulating," Bekedam told reporters.

China's seeming lack of reporting of outbreaks among birds makes it difficult for experts to track the virus as it spreads and potentially check its evolution. Experts worry that if outbreaks are not controlled the virus could mutate into a form more easily transmitted between people, potentially causing a worldwide pandemic.

International experts have repeatedly complained about Chinese foot-dragging in providing information on bird flu and other emerging diseases like severe acute respiratory syndrome, or SARS.

In the latest case, the Health Ministry told WHO that the soldier was stationed in the southern province of Fujian and people who had close contact were under medical observation but showed no signs of disease, the WHO's Beijing spokeswoman, Joanna Brent, said.

One of China's two other reported human cases of bird flu this year was a farmer in Fujian. The other was a 16-year-old boy who died in March in the eastern province of Anhui _ the country's 15th fatality from the disease.

Additionally, China's military is prone to secrecy, complicating cooperation with international organizations. Last year, it was disclosed that new tests on the body of a 24-year-old soldier who died in 2003 in Beijing confirmed that he succumbed to bird flu _ one of the earliest deaths in a resurgent wave of bird flue that swept through the region.

The military has yet to provide a promised virus sample from that case, the WHO has said.

Two other specimens from recent human cases in China arrived in the United States last week from the Health Ministry after a lag of about a year.

Bekedam said the WHO was working with the Agriculture Ministry to get more virus samples from last year and this year.

While the WHO does not mandate sharing virus samples, they are needed to produce diagnostic tools and vaccines. The lack of cooperation, experts say, could slow efforts to track diseases and develop vaccines and other strategies to deal with them.

Bird flu has killed at least 186 people since H5N1 started ravaging poultry flocks in late 2003.