Study: H7N9 virus can spread between humans
Source: Agencies |
00:06 UTC+8 May 25, 2013
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THE H7N9 bird flu virus may be capable of spreading from human to human and be transmitted not only through direct contact but also through airborne exposure, researchers at the University of Hong Kong have found.
A study presented at a news briefing yesterday found that three ferrets - the main animal used for research into human influenza - placed in close contact with ferrets injected with H7N9 contracted the virus. One out of three that were kept in different cages became infected through airborne exposure.
The World Health Organization has said it had no evidence of "sustained human to human transmission" of the virus. The WHO in China did not immediately respond to a request for comment on the study.
"The findings suggest that the possibility of this virus evolving further to form the basis of a future pandemic threat cannot be excluded," said the research team led by bird flu expert and microbiologist Yi Guan.
The team also found that some infected animals did not develop fever and other clinical signs, indicating that asymptomatic infections among humans are possible, making the virus harder to detect and control. The virus can also infect pigs, but could not be transmitted from pig to pig or from pigs to other animals, the study showed.
The findings come just days after the WHO said the virus appeared to have been brought under control in China thanks to restrictions at bird markets.
H7N9 has relatively mild clinical signs in ferrets, according to the study. All the animals infected with the virus in the experiments presented symptoms for no more than seven days and all recovered from the disease.
The researchers said that cases where humans died or became extremely ill were triggered by additional causes.
"All the deceased or seriously ill patients, (their illness) are due to other causes," said Dr Zhu Huachen from the research team.
The H7N9 virus is known to have infected 130 people in Chinese mainland, but no cases have been detected since early this month.
A study presented at a news briefing yesterday found that three ferrets - the main animal used for research into human influenza - placed in close contact with ferrets injected with H7N9 contracted the virus. One out of three that were kept in different cages became infected through airborne exposure.
The World Health Organization has said it had no evidence of "sustained human to human transmission" of the virus. The WHO in China did not immediately respond to a request for comment on the study.
"The findings suggest that the possibility of this virus evolving further to form the basis of a future pandemic threat cannot be excluded," said the research team led by bird flu expert and microbiologist Yi Guan.
The team also found that some infected animals did not develop fever and other clinical signs, indicating that asymptomatic infections among humans are possible, making the virus harder to detect and control. The virus can also infect pigs, but could not be transmitted from pig to pig or from pigs to other animals, the study showed.
The findings come just days after the WHO said the virus appeared to have been brought under control in China thanks to restrictions at bird markets.
H7N9 has relatively mild clinical signs in ferrets, according to the study. All the animals infected with the virus in the experiments presented symptoms for no more than seven days and all recovered from the disease.
The researchers said that cases where humans died or became extremely ill were triggered by additional causes.
"All the deceased or seriously ill patients, (their illness) are due to other causes," said Dr Zhu Huachen from the research team.
The H7N9 virus is known to have infected 130 people in Chinese mainland, but no cases have been detected since early this month.
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