H7N9 avian flu
The influenza A (H7N9) virus is one subgroup among the larger group of H7 viruses that normally circulate among birds. A number of human infections of the H7N9 virus have been reported in eastern China, mostly in the Yangtze River Delta region since late March 2013. Some of the patients have died of severe pneumonia brought on by the virus.
H7N9 bird flu appears contained, UN health experts say
International experts praise China's efforts, but note outbreak has cost economy US$6.5b
The H7N9 virus appears to have been brought under control in China largely due to restrictions at bird markets, but caused some US$6.5 billion in losses to the economy, UN experts said.
Health authorities worldwide must be on the lookout to detect the virus, which could still develop the ability to spread easily among humans and cause a deadly influenza pandemic, the experts said.
The new bird flu virus is known to have infected 130 people in mainland China since emerging in March, including 36 who died, but no cases have been detected since early May, Health Minister Li Bin told the World Health Organisation.
One case was found in Taiwan in April, making a total of 131.
"The immediate outbreak has been controlled, but it is also unlikely that virus has simply disappeared. We believe we need go another autumn/winter/spring season to know," said Dr Keiji Fukuda, WHO assistant director general for health security.
"We also have high concern over the potential, I stress the potential, to gain the ability to sustain transmissibility."
There was no evidence of sustained spread among people and "most cases probably resulted from infected poultry or perhaps contamination related to live poultry markets", Fukuda said.
Li said local authorities had shut down live poultry markets "temporarily or permanently as needed" to control the source of outbreaks in 10 provinces.
Methods of transporting poultry had been standardised to reduce the virus' spread among birds, she said.
The central government had spent 600 million yuan (HK$752 million) to support healthy development of the poultry industry, Li said.
"In view of the present situation, H7N9 is preventable and controllable," she said. "There has been no qualitative change in the epidemic. Cases are sporadic and there has been no genetic mutation [of the virus]."
H7N9 is highly pathogenic in humans, causing severe respiratory disease, but is not virulent among birds, making it nearly impossible for farmers to detect, experts said.
There is "no red flag" for H7N9 among poultry, unlike H1N1 which kills off flocks, said Dr Juan Lubroth, chief veterinary officer at the UN's Food and Agriculture Organisation.
"There have been no [human] cases since May 8, that is a good indication and means measures are being taken seriously," said Dr Bernard Vallat, head of the World Organisation for Animal Health.
"Now when the virus is found at market, all birds are killed, that is important too."
Out of 60,000 samples taken from birds, 53 were found to carry the virus, the Health Ministry's Dr Liang Wannian said.