As winter chill takes over, bird flu returns, threatening to become a seasonal presence in parts of Asia.

The intervals between outbreaks shortened suddenly last week, prompting the World Health Organization to issue a global alert.

As of today, cases of poultry or human infections have been reported in Vietnam, Indonesia, Nigeria, the Republic of Korea, Japan and China

Two dead birds have tested positive for the H5 bird flu in Hong Kong. The source of the highly pathogenic type A (H5N1) virus that infected a man in Anhui Province remains a mystery.

It remains to be seen if those are isolated cases or precursors to another outbreak. According to scientists, we will not get a clear answer until February and March.

But the current peak of seasonal flu infections in north China deserves special attention. Places like Beijing are witnessing an annual peak in flu outbreaks. Although the overall situation is still normal and the peak is said to have passed, experts have their own worries.

Once regular flu infections coincide with those of bird flu, things will become very complicated, or even dangerous. Confluence of the two may confuse ordinary citizens and doctors, because their initial symptoms are very similar.

The feared variation of bird flu viruses may occur as a result, which may in turn make possible human-to-human infection of the life-threatening disease.

Though there still is no evidence of human-to-human transmission of bird flu, the WHO has similar concerns and has warned of a major outbreak caused by potential virus variations.

According to a national animal epidemic prevention plan released recently by the State Development and Reform Commission, our government wants to bring major epidemics in animals, including bird flu, under effective control and eliminate them in some regions by 2015.

Epidemic emergencies in the past few years have helped the nation to lay a decent foundation for epidemic information sharing.

Beyond that, the average citizen must be mobilized to improve our collective immunity. We have developed effective flu vaccines, and a new one for bird flu is reportedly available for human use.

Encouraging vaccine use may be an important part of the government's efforts to organize a defense network.

(China Daily January 15, 2007)