HONG KONG - Health officials announced yesterday that tests had confirmed more cases of Asia's twin health threats this winter, bird flu and SARS.
China said two people previously categorized as suspected cases of severe acute respiratory syndrome had been reclassified as confirmed cases.
Vietnam said four more people had fallen ill with the H5N1 strain of flu spreading through Asian poultry.
World Health Organization officials said they had not confirmed either the additional Vietnamese bird flu cases or the reclassified Chinese SARS cases, and needed more information.
The WHO has begun describing avian influenza, popularly known as bird flu, as the bigger threat.
Influenza tends to be more infectious than SARS, the organization said, with flu outbreaks moving swiftly around the world each winter - killing tens of thousands of people in a mild year, and hundreds of thousands or more in a bad year.
None of the latest cases of bird flu appears to involve person-to-person transmission, said Bob Dietz, a WHO spokesman in Hanoi, Vietnam.
But as people become infected from chickens, doctors warn, the virus could mutate if caught by someone exposed to a human flu strain. Such a combined flu virus could be more easily transmitted among people.
The H5N1 strain of flu has been detected in chicken flocks in at least 15 Vietnamese provinces. Other possible cases have been found in 10 other provinces and in Japan and South Korea. The H5N2 strain, which might be less dangerous, has surfaced in chickens in Taiwan.
The H5N1 version is especially feared because humans have little immunity to it and it is hard to create a vaccine against it. Some evidence suggests that H5N1 is unusually lethal.
The Vietnamese Ministry of Agriculture and Rural Development told the WHO yesterday that more than a million chickens have been killed in just two of the provinces with outbreaks.
Hong Kong and mainland Chinese officials announced separately that samples sent here from a 20-year-old waitress and a 35-year-old businessman in Guangzhou, a city in southern China 80 miles from Hong Kong, had been confirmed as showing the SARS virus, which comes from a family of viruses known as corona viruses.