Eight more human cases of bird flu have been reported in Viet Nam, according to the United Nations health agency, bringing the total since mid-December to 41, 16 of them fatal, in the latest outbreak of a disease that in a worst-case scenario could kill tens of millions people worldwide.
The World Health Organization (WHO) is seeking further details from the authorities. Earlier this month the agency said there was currently no evidence that the virus was spreading easily from person to person. Three additional cases of the H5N1 virus strain have been reported from neighbouring Cambodia.
WHO has stressed the need for scientists to share the viruses from recent clusters of cases and determine possible changes in the behaviour of the H5N1 to assess the risk of an influenza pandemic. The so-called Spanish flu pandemic of 1918-1920, unrelated to the present virus, is estimated to have killed between 20 million and 40 million people worldwide.
WHO is concerned that continuing transmission to humans might give avian and human influenza viruses an opportunity to exchange genes, facilitating a pandemic.
Overall there have been some 90 reported infections, about 50 of them fatal, since the first human case linked to widespread poultry outbreaks in Viet Nam and Thailand was reported in January last year. Nearly 140 million domestic birds have died or been culled over the past year in southeast Asia in an effort to curb the spread of the disease.