H7N9 virus 'one of the most lethal'
Source: Agencies |
April 25, 2013, Thursday
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Print Edition
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The new strain of bird flu that has killed 22 people in China is "one of the most lethal" of its kind and is more easily transmissible to humans than an earlier strain that has killed hundreds around the world since 2003, a top World Health Organization official said yesterday.
The H7N9 virus has infected 108 people in China since it was first detected in March, according to the Geneva-based WHO. Although it is not clear exactly how people have been infected, WHO experts see no evidence so far of the most worrisome scenario - sustained transmission between people.
An international team of experts led by the WHO and the Chinese government conducted a five-day investigation in China, but said they were no closer to determining whether the virus could become transmissible between people.
Keiji Fukuda, WHO's assistant director-general for health security, said "the situation remains complex and difficult and evolving.
"When we look at influenza viruses, this is an unusually dangerous virus for humans," Fukuda said at a briefing, also naming the previous H5N1 strain that killed 30 of 45 people infected in China since 2003.
Although the H7N9 strain in the current outbreak has a lower fatality rate to date, he added: "This is definitely one of the most lethal influenza viruses that we've seen so far."
Fukuda stressed that the team was still at the beginning of its investigation and that "we may just be seeing the most serious infections" at this point.
The experts said that what was mystifying about the virus was the absence of visible illness in poultry, "making it harder to track and control."
Fukuda also said that, based on the evidence, "this virus is more easily transmissible from poultry to humans than H5N1," the virus which has killed 371 people worldwide since 2003.
Ho Pak-leung, an associate professor in the microbiology department at the University of Hong Kong, noted in the British Medical Journal that in the two months since it was first detected, the H7N9 flu had already resulted in almost twice as many confirmed infections in China as H5N1 caused there in a decade.
Besides the initial cases of H7N9 in and around Shanghai, others have been detected in Beijing and five provinces.
Samples from chickens, ducks and pigeons from poultry markets have tested positive for the H7N9 virus, but those from migratory birds have not, said Nancy Cox, director of the influenza division at the US Centers for Disease Control and Prevention.
"At least we can now understand the likely source of infection is poultry," Cox said.
The experts also looked at poultry samples from farms but found nothing, said Malik Peiris, a clinical virologist at the University of Hong Kong.
There has been a "dramatic slowdown of cases" in Shanghai, which recorded most of the deaths, said Anne Kelso, Melbourne-based director of the WHO Collaborating Center for Reference and Research on Influenza.
"This is very encouraging at this stage of the outbreak," she said.
After Shanghai closed down its live poultry markets in early April, "almost immediately there was a decline in detection of new cases," Kelso said.
The H7N9 virus has infected 108 people in China since it was first detected in March, according to the Geneva-based WHO. Although it is not clear exactly how people have been infected, WHO experts see no evidence so far of the most worrisome scenario - sustained transmission between people.
An international team of experts led by the WHO and the Chinese government conducted a five-day investigation in China, but said they were no closer to determining whether the virus could become transmissible between people.
Keiji Fukuda, WHO's assistant director-general for health security, said "the situation remains complex and difficult and evolving.
"When we look at influenza viruses, this is an unusually dangerous virus for humans," Fukuda said at a briefing, also naming the previous H5N1 strain that killed 30 of 45 people infected in China since 2003.
Although the H7N9 strain in the current outbreak has a lower fatality rate to date, he added: "This is definitely one of the most lethal influenza viruses that we've seen so far."
Fukuda stressed that the team was still at the beginning of its investigation and that "we may just be seeing the most serious infections" at this point.
The experts said that what was mystifying about the virus was the absence of visible illness in poultry, "making it harder to track and control."
Fukuda also said that, based on the evidence, "this virus is more easily transmissible from poultry to humans than H5N1," the virus which has killed 371 people worldwide since 2003.
Ho Pak-leung, an associate professor in the microbiology department at the University of Hong Kong, noted in the British Medical Journal that in the two months since it was first detected, the H7N9 flu had already resulted in almost twice as many confirmed infections in China as H5N1 caused there in a decade.
Besides the initial cases of H7N9 in and around Shanghai, others have been detected in Beijing and five provinces.
Samples from chickens, ducks and pigeons from poultry markets have tested positive for the H7N9 virus, but those from migratory birds have not, said Nancy Cox, director of the influenza division at the US Centers for Disease Control and Prevention.
"At least we can now understand the likely source of infection is poultry," Cox said.
The experts also looked at poultry samples from farms but found nothing, said Malik Peiris, a clinical virologist at the University of Hong Kong.
There has been a "dramatic slowdown of cases" in Shanghai, which recorded most of the deaths, said Anne Kelso, Melbourne-based director of the WHO Collaborating Center for Reference and Research on Influenza.
"This is very encouraging at this stage of the outbreak," she said.
After Shanghai closed down its live poultry markets in early April, "almost immediately there was a decline in detection of new cases," Kelso said.
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