BEIJING • China is grappling with its worst bird flu outbreak, with the death toll so far this winter rising to at least 108, stirring further concerns about the spread of the deadly virus.
Chinese disease control experts have warned the public to stay alert against the H7N9 avian flu, saying that more than 340 cases of human infection have been reported since last October. South Korea and Japan are also battling their own major outbreaks and have culled millions of chickens.
The virus is likely to strike in winter and spring, and farmers have in recent years ramped up measures such as cleaning regimes to prevent the disease from striking. China has confirmed five bird flu outbreaks among poultry this winter, which has led to the culling of more than 175,000 birds. Some live poultry markets have been closed after people and chickens were infected by the avian flu strains
China is the world's third-largest producer of broiler chickens and second-biggest poultry consumer.
The new strain of H7N9 bird flu virus could become drug-resistant, experts say, while a leading specialist in respiratory diseases warns that it might be resistant already.
Two human cases have been reported in Guangdong province, with the strain showing resistance to oseltamivir phosphate, a commonly used drug in the prevention and treatment of flu, said Mr Zhong Nanshan, a member of the Chinese Academy of Engineering, according to a report in Nanfang Daily, a newspaper in the provincial capital of Guangzhou.
Death toll from the H7N9 avian flu.
Number of cases of human infection that have been reported since October.
Although the two patients are resistant to the drug, oseltamivir phosphate has been effective for most human H7N9 cases, Mr Zhong was reported as saying. "This shows that most H7N9 viruses have not mutated to the new strain," he said.
Mr He Jianfeng, chief expert in infectious disease at the Guangdong Provincial Centre for Disease Control and Prevention, said the drug could still have an effect.
"Both patients have used oseltamivir phosphate before, so it is not known whether the drug resistance is caused by previous use of the drug or by a mutation of the virus," Mr He told Nanfang Daily.
"But the possible drug-resistant nature of the new strain deserves more attention."
Much of China has seen the H7N9 outbreak since the start of winter. In most cases, it has been linked to exposure to live poultry. Last month alone, 192 human cases of the virus, including 79 deaths, were reported, making it the worst outbreak since the virus was first reported in China in 2013, according to the National Health and Family Planning Commission.
The new strain is more dangerous to poultry, and not humans at the moment, according to a statement by the Chinese Centre for Disease Control and Prevention (CCDC).
Current research shows that the H7N9 virus is not easily transmitted between humans, according to the World Health Organisation.
Mr He Xiong, deputy director of the CCDC, said the new strain does not result in increased risk of human-to-human transmission of the virus, but unlike other H7N9 viruses, it can cause diseases in poultry, which should be studied further.
Meanwhile, four vaccines have been approved for clinical trials by China's top drug regulator, according to the Beijing Food and Drug Administration. No vaccines for the H7N9 bird flu are on the market in China or overseas at present.
REUTERS, XINHUA, CHINA DAILY/ASIA NEWS NETWORK