China warns on bird flu; case reported in Taiwan

Chinese health officials are warning that the death toll from the H7N9 bird flu is likely to rise in the weeks and months ahead.

The warning comes as Taiwan confirmed an H7N9 infection in a traveler who returned to the island from China, the first case of the virus outside the mainland.

A 53-year-old Taiwanese man tested positive after a business trip to the eastern city of Suzhou and returning to Taiwan via Shanghai, officials said. The patient, who is in critical condition in an isolation room, did not come into contact with birds, they said.

In a report on the outbreak that began in China in February, doctors and researchers from several public health agencies said they suspected that most of the 82 people with confirmed cases of bird flu contracted the H7N9 virus from healthy-looking animals.

"To date, the mortality rate is 21 percent, but since many . . . patients with confirmed H7N9 virus infection remain critically ill, we suspect that the mortality may increase," they wrote in their study, published online Wednesday by the New England Journal of Medicine. "Since this H7N9 virus appears to have emerged recently to infect humans, population immunity is expected to be low, and persons of any age may be susceptible to infection."

The 82 confirmed patients ranged in age from 2 to 89, but most were at the higher end of that range; 46 percent were at least 65.

Among the 17 people confirmed to have the virus who died, the median time from onset of illness to death was 11 days. Their deaths were attributed to acute respiratory distress syndrome or multi-organ failure.

Sixty other patients confirmed to have the H7N9 virus remain critically ill, according to the report. The outcome of their cases could push the death toll higher.

The health officials strongly suspect that most of the patients became sick through contact with infected but healthy-looking animals, mainly in live poultry markets.

Until scientists are able to figure out exactly how the virus spreads from animals to humans, health officials should consider measures such as closing live poultry markets and culling the birds, the health officials wrote.