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Avian Influenza
on July 1, 2009

H5N1 human infections in China unexplained and worrying

International community should be concerned about an emerging pattern in human cases of avian flu.

China has announced the death of its 17th victim of the H5N1 strain of the highly pathogenic avian influenza (HPAI) virus. It was a 24-year-old man from Nanjing in the Jiangsu province of eastern China who died in late November. This is the first death for five months and it is not particularly worrying in itself. However, the background of his infection and death and subsequent announcement that his 52-year-old father contracted the same disease about one week later certainly is.

Xinhua News Agency said the man had no contact with dead poultry and there had been no reported poultry outbreak in the province. The local government adopted appropriate prevention and control measures and all 69 people having close contact with the victim were put under strict medical observation. “So far, they have shown no signs of symptoms," claimed the report.

World Health Organisation (WHO) said the Chinese authorities had told them about the case and they were in constant touch with the Ministry of Health. “It looks like Ministry of Health is doing the right thing in terms of follow-up action,” commented WHO spokeswoman, Joanna Brent, referring to surveillance of the victim’s close contacts. “At this stage, we don't have any more information about how he would have contracted it,” she said.

Most likely, the first infection, at least, came from infected poultry. Wild birds could be an option while reports this year from other Asian countries indicate H5N1 is entrenched in the Indonesian cat population and is possibly transmitted by rodents to poultry in Japan.

A Reuters report quoted Chinese Health Ministry spokesman, Mao Qun'an, as saying analysis of a sample taken from the younger man indicates that the HPAI virus has not mutated, but he could not exclude the possibility of human-to-human infection in this case. “The virus is still avian and has not undergone a mutation in its nature,” he told a news conference.

Hong Kong is invariably the best source of information about what is really going on in mainland China. According to Reuters, a Hong Kong newspaper controlled by the mainland claimed that father and son had both eaten chicken that was not fully cooked. Ta Kung Pao newspaper cited unnamed sources as saying they had eaten the partly cooked chicken in a restaurant in Nanjing, capital of Jiangsu.

CIDRAP says many experts are sceptical about China’s persistent claims that virtually no human H5N1 cases have had any contact with infected poultry. A classic case was in June 2007 when WHO confirmed a 19-year-old male soldier serving in Fujian province died from an H5N1 infection without  having been anywhere near infected poultry (according to the Chinese authorities).

At that time, WHO spokesman, Gregory Hartl, told Associated Press that only one of China’s H5N1 cases had reported contact with sick poultry. He went on to raise questions about accuracy and effectiveness of the Chinese government’s monitoring of the disease in birds. Similar doubts are being expressed this time round by Julian Tang Wei-tze, a virologist based in Hong Kong, as to whether the latest victim really had no contact with infected birds. “It's about the accuracy of their contact history. With an incompatible history it is hard to exclude any contact with infected birds, their droppings or people,” he told The Standard, a Hong Kong business newspaper, on 4 December 2007.

Subsequent infection of the victim’s father, unless both were in contact with infected poultry (unknown to the authorities), is especially worrying because it strongly indicates human-to-human transmission. WHO are clearly concerned and especially about the second infection. Spokesman John Rainford told the BBC, “We are concerned. The fact that we have two cases here without necessarily a clear source of animal infection and within the same family means we need to make sure we do a thorough investigation.”

Other contacts are so far free of disease which is heartening but is in line with the view of some experts. They believe H5N1 can only move between most people with difficulty because of genetic differences, but this would clearly not apply in the same degree to blood relatives. The large human H5N1 cluster of 8 people on the Indonesian island of Sumatra during May 2006 showed all infected persons were blood relatives. Spouses were unaffected despite close contact with other infected family members. This means the workforce on a family-run poultry farm could be at particular risk if the virus makes a move from poultry to people.

With its own past experiences of H5N1 in 1997 and 2002/03 and also SARS, Hong Kong wasted no time in introducing strict legislation to avert any health crisis developing from these worrying developments on mainland China. Under the new bill, the Health Minister will have authority to seize any object suspected to be an infectious agent and to detain anyone believed to be a disease carrier for isolation, quarantine and medical examination. He can also order the arrest of anyone who absconds from medical detention.

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