A world-class virus hunter has taken his mission to China to do battle with what many consider to be the next big threat in the virus world.

Dr. Guan Yi is on the front lines in the war against H5N1, better known as bird flu. One of the world's leading researchers in the field, he and his team are leading the hunt for clues to when the bird flu virus will mutate into a form that will allow human-to-human transmission, and start a pandemic.

He believes the mutation will occur in China first, so he and his team have set-up operations at Hong Kong University.

"We hope to catch the early phase of the human case and stop it," he told CTV News. "This is the major reason I came back to Hong Kong to work. I'm waiting for it."

Dr. Guan certainly has the credentials for the job. He was the researcher who discovered civet cats were the main carrier for Severe Acute Respiratory Syndrome (SARS), and as a result he's credited for stopping a second outbreak. He has also tracked the origins of bird flu to geese in southern China, the birthplace of many of the world's flu epidemics.

Dr. Guan is no stranger to the bird flu virus. He started tracking it in 1997, when bird flu surfaced in poultry in Hong Kong, going on to claim the lives of six people.

Since then his teams have analyzed 150,000 samples from across Asia. They've watched the virus mutate 20 times, but they still can't predict what it will do next.

The world's scientific community has no method so far of determining what mutation or change in the virus will allow human-to-human transmission, but Dr. Guan has made it his mission to find out.

He believes at-risk countries like China and Vietnam are overusing animal vaccines in an effort to stop the disease. His research indicates the virus can still mutate in birds which have been vaccinated.

"They meet in the host, they mix together. When they repackage the virus, maybe the face is H5N1 but the gene inside is different," he said.

Dr. Guan believes the only true solution is a drastic one. The only way to stop the virus, he said, is for infected countries to kill their entire domestic bird populations, and start over.

But that's a difficult, controversial and expensive decision for politicians to make.

In the meantime, he hopes his work will help world leaders make informed decisions about how to deal with the threat of a bird flu pandemic.

With a report from CTV's Steve Chao