Last updated: April 3, 2013 1:15 pm

China confirms several more bird flu cases

A farmer holds a chicken as she poses for a photograph at a hennery in Beifan village of Zouping county, Shandong province on April 1 2013©Reuters

Chinese authorities have confirmed several new cases of a deadly new strain of bird flu, raising questions over whether a new flu pandemic could be emerging in eastern China.

Authorities confirmed two additional cases of H7N9 on Wednesday – bringing to nine the total cases to date. The infections prompted Vietnam to announce a ban on poultry imports from China, while neighbouring Hong Kong has strengthened surveillance of flu cases.

Of the nine confirmed cases of H7N9, three people have died while the rest are in hospital in critical condition. Authorities said the infections occurred between late February and late March, and that the cause of infection was unknown.

Wendy Barclay, professor of virology at Imperial College London, said scientists had already decoded the full genetic sequence of the Chinese H7N9 strain, which shows it to be a “low pathogenic virus” for birds.

This will make it harder to detect in flocks than the highly pathogenic H5N1, the avian flu virus causing most concern over the last few years, which has a devastating effect on domestic fowl.

John MCauley, director of the World Health Organisation Collaborating Centre on Influenza, added: “Analysis of [H7N9] isolates at the Chinese Centre for Disease Control and Prevention has shown that the viruses are sensitive to the anti-influenza drugs Tamiflu and Relenza.”

Little is known about how H7N9 is transmitted from birds – the main mixing vessel for new viral strains – to humans. A pork trader, a poultry culler and a cook are among the nine people infected. Chinese health authorities said no human-to-human transmission has been discovered.

But Chinese citizens have questioned on the internet whether they are getting the full story about the new virus, after Beijing’s cover-up of the deadly Sars in 2002 and 2003.

On Tuesday, public fears of a cover-up mounted when unverified online reports claimed a new case in Nanjing, more than 300km away from the initial infections. Those reports turned out to be true, and the Nanjing case was one of the four new cases that were announced on Tuesday night.

“They are doing it again, hiding it for days like they did when Sars broke out,” wrote one Weibo user.

To help combat the virus, Shanghai told hospitals to step up flu monitoring and testing, and to stock up on supplies for a possible outbreak.

Shanghai authorities denied there was any link between the new virus and the thousands of dead pigs that were dumped in the city’s main waterway last month.

Yin Ou, deputy director of the Shanghai Municipal Agricultural Committee, told reporters the city had tested 34 river pigs for the H7N9 virus and all were negative. He added that the chicken and pork being sold in Shanghai was safe, with no cases of avian flu or swine flu found in the city’s food markets.

Leung Ting-hung, Hong Kong’s top disease control official, said the new influenza strain should not be taken lightly.

“The mortality of Influenza A [H7N9] is very high,” Mr Leung said. “Although there is no evidence to show human-to-human transmission, the mutation potential of the virus is high.”

“At present we do not think it has enough mutations to make it transmissible through the air between people,” said Prof Barclay.

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