A healthy 81-year-old man from Vietnam's northern Thai Binh province, maternal grandfather of two bird flu patients, has just been confirmed to contract H5N1, while the World Health Organization (WHO) found the virus in samples from seven local people, according to local newspaper Youth Wednesday.

Although the old man has been in good health condition in his hometown since he and his 21-year-old grandson and 14-year-old granddaughter ate sick poultry, local health agencies took his samples for virus testing which showed that he is infected with H5N1.

Earlier, the young man and the girl were confirmed to contract the disease, and now have remained hospitalized at the Hanoi-based Institute of Tropical Diseases. He exhibited symptoms on Feb. 14 and was admitted to the institute on Feb. 20. His sister developed symptoms on Feb. 21, and was hospitalized the following day.

In the most recent outbreak of bird flu starting in late December 2004, Vietnam has detected 23 local people to contract H5N1, of whom 13 have died. The latest fatality was a 69-year-old man from Thai Binh, who developed symptoms on Feb. 19, was admitted to hospital the same day, and died on Feb. 23.

The WHO has said its retesting on samples from seven people, which have been tested negative to H5N1 in Vietnam in January, showed that they were infected with the virus.

Earlier this year, staff from WHO, Japan's National Institute of Infectious Diseases in Japan, and Centers for Disease Control and Prevention in the United States began working with health authorities in Vietnam to improve the sensitivity and reliability of laboratory diagnostic tests, the organization said.

"This activity, which aimed to upgrade laboratory capacity and included a training component, involved the retesting in Tokyo of specimens from several persons initially classified in Vietnam in January as negative for H5N1 infection. Retesting detected H5N1 in specimens from seven persons," the WHO said in a statement posted on its website on March 7.

WHO is awaiting further details about these cases, including outcomes, it said. Bird flu, which has killed and led to the forced culling of more than 1.5 million fowls in 35 cities and provinces in Vietnam since January, is subsiding. Eighteen out of the 35 localities have detected no new bird flu-affected spots for at least three weeks, said the country's Department of Animal Health.

Source: Xinhua