Two people in southwest China have tested positive for the H5N1 bird flu virus and are critically ill, state news agency Xinhua said on Sunday, citing the Chinese health ministry.
A 21-year-old woman and 31-year-old man in Guiyang had tested positive for the highly pathogenic H5N1 virus on Sunday after developing symptoms on February 2 and February 3 respectively, Xinhua cited health authorities as saying.
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"They are in critical condition and medical workers are carrying out emergency treatment," the health ministry was quoted as saying. "No epidemiological connections have been found between the two cases."
Millions of Chinese are currently travelling in crowded buses and trains across the country to celebrate the Lunar New Year, raising the risk of the spread of infectious diseases.
People who had close contact with the patients are under medical observation but none have fallen ill, the news agency said.
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The pair did not have contact with fowls before they fell ill, Xinhua said. In most cases, victims had direct contact with infected birds, mostly chickens.
The virus is especially abundant in the feces and respiratory secretions of affected birds.
The H5N1 virus mainly affects birds, but occasionally jumps to people.
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Experts fear it may mutate into a form that could spread easily among humans who have no natural immunity against it.
The H5N1 virus has infected more than 600 people since it was first detected in Hong Kong in 1997 and is usually fatal.