Image copyright Action on Armed Violence Image caption A H5N1 strain of bird flu hits the UK last year
A variant of the bird flu virus “poses a very high” risk to the global population, warns the World Health Organization.
It adds that there have been “an unprecedented number of spike mutations” with this strain, also known as Omicron variant A.
WHO has not yet linked this to recent outbreaks in humans of the virus – H5N1 or H7N9.
But it says a further spike mutation is “likely” with “local and migratory birds”.
The organisation is, however, urging countries to be vigilant for the H5N1 and H7N9 viruses, and says that action needs to be taken to contain the spread of the H5N1 and H7N9 viruses.
“Anecdotal reports suggest an increased number of spike mutations during recent bird flu outbreaks,” the WHO says in a new report.
“This suggests that there is high risk of a further spike mutation or amplification of different molecular elements, which could potentially spread the virus from the birds to people”.
The agency says that it “strongly recommends” an enhanced surveillance programme to detect H5N1 and H7N9 viruses, to increase collaboration between labs and agencies, and to release infected animals from poultry flocks.
In August 2017, WHO said that 95% of flu viruses now vary from what is termed the “A” virus family, and the proportion is likely to be higher in mammals.
The reason for this, it says, is because the diversity of viruses is high, which means it is harder to recognise virus mutations.
The WHO report comes as scientists who have studied several bird flu viruses for the first time recently reported that H5N1 H7N9, reported in South Korea last year, could be an Influenza A variant.
They called for a global response, saying there was no evidence that the virus was spreading from person to person.
In 2001 and 2002, bird flu killed 229 people in Asia. In 2014, 153 died. In 2017, there were no human deaths.