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Friday 25th May 2018

Bird flu mutation bad for humans

5th October 2007

The H5N1 avian influenza virus has mutated into a form that will enable it to infect humans more easily, researchers say.


The virus, previously adapted to live in the body temperature of a bird at 41 degrees Celsius (106F), has mutated so as to survive in the cooler environment of the human upper respiratory tract, according to Yoshihiro Kawaoka of the University of Wisconsin-Madison.

Kawaoka and his team have now identified a specific change that could make bird flu grow in the upper respiratory tract. The viruses now circulating in Africa and Europe were considered to be closest to becoming a human virus, he said.

Recent samples of virus taken from birds in Africa and Europe all carry the mutation, Kawaoka and colleagues report in the Public Library of Science journal PLoS Pathogens.

Kawaoka said he had published the findings not to scare the public, but to keep the scientific community abreast of the latest developments.

However, the virus would have to make more mutations yet if it were to become capable of passing easily between humans and causing a pandemic, which experts fear could spread rapidly around the world, killing millions.

H5N1 was carried across Asia to Africa and Europe by migratory birds after a mass outbreak among wild waterfowl in 2005 at Qinghai Lake in central China, where hundreds of thousands of migratory birds congregate.

The descendants of that strain are the ones that carry the mutation, and were closer to human influenza, Kawaoka said.

He said researchers were unsure of precisely how many more mutations would be needed for H5N1 to spark a pandemic.

The virus has infected 329 people globally since 2003, of whom 201 have died.

While the virus is widely considered to infect humans who come into contact with infected birds, researcher concluded that a girl in Thailand probably passed the virus to at least her mother in September 2004, causing fatal disease, in the first published account of probable secondary human transmission, resulting in severe disease, of any avian influenza virus.

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