2008-04-30 17:09 Caijing Magazine

http://english.caijing.com.cn/20080430/59003.shtml

Health officials are debating whether person-to-person transmission of the deadly bird flu virus has occurred in China. But even if it hasn't yet, it may someday.

By staff reporter Li Hujun

The case of a father and son infected with H5N1 bird flu in Nanjing remains controversial, more than four months after the report triggered close scrutiny from medical specialists worldwide.

Intensifying the debate was Wang Yu, director of China’s Center for Disease Control and Prevention (CDC), who along with colleagues wrote an article published April 8 in the British medical journal The Lancet citing the case as a “probable, limited person-to-person transmission” of highly pathogenic avian influenza A, that is, H5N1.

Yu’s article marked the first official report from Chinese scholars about a possible case of person-to-person bird flu transmission in the country. It said experts think the virus was transmitted to Lu Wei from his son, Lu Kan. At the time, the son was in a hospital and being cared for by the father.

But later Mao Qun An, a spokesman for the Ministry of Health --  the overseer of the CDC -- insisted at a press conference that the virus had jumped to each patient from a bird. “There is still no conclusive, epidemiological or biological, evidence to prove a person-to-person transmission,” Mao said.

A representative of the World Health Organization (WHO) in China, Hans Troedsson, backed the ministry’s opinion. He told Caijing that Yu’s article only showed that “limited and non-continuous person-to-person transmission” may have occurred in China.

According to WHO statistics, 381 human cases of H5N1 in 14 countries had been confirmed between November 2003 and mid-April 2008, killing 240 people.

Most cases affected only a single individual. But one-fourth affected two or more people with close contact who displayed symptoms simultaneously. Limited person-to-person cases probably happened in Vietnam, Thailand and Pakistan.

But only one direct case of person-to-person transmission has been confirmed by scholars. It happened in Indonesia when eight members of a rural family were infected. The female patient who first showed symptoms was found to have transmitted the virus to her niece, and from that point the virus continued spreading to others.

In China, more than one case of person-to-person transmission has been suspected. Guan Yi, a microbiology professor at Hong Kong University, raised the possibility in connection with a 1997 bird flu outbreak in Hong Kong. In a 2003 case, three members of a Hong Kong family were infected with the virus in the mainland’s Fujian province.

A suspicious case drawing the most attention on the mainland involved the death of He Yin, a 12-year-old girl who died in October 2005 after being diagnosed with an unknown strain of pneumonia. Around the same time, her 9-year-old brother was hospitalized. But because the girl’s corpse was cremated, it was impossible to determine whether the boy contracted the bird flu from his sister.

A team led by Chinese researcher Gu Jiang discovered that the bird flu virus could be transmitted from mother to fetus. The study, published in September’s The Lancet, was based on the autopsy of 24-year-old Zhou Maoya, who died of bird flu in 2005 four months into pregnancy.

The case of Lu Kan has so far been harder to crack. He had contact with his father as well as about 90 other people, an overwhelming number of people. Yet only the father was infected, leading some scientists to guess that genetics have an influence in transmission.

Officially, Chinese health authorities warned that “people have been infected with a new kind of flu virus, but person-to-person transmission has not occurred.” Yet they still remain cautious. Most poultry in China has already been immunized, but bird-to-bird transmission has not entirely stopped yet, raising concerns about future human infections.

Certainly, no one is suggesting the possibility of widespread person-to-person transmission of the virus. Jeremy Farrar, a leading bird flu researcher in Oxford University, said there are no signs that such events have occurred anywhere in the world.

But Farrar warned that, as long as bird flu continues breaking out among poultry, it is “just a matter of time” before it begins jumping between people.

Some experts have criticized a lack of coordination between the animal immunization program managed by the Ministry of Agriculture and disease control organizations under the Health Ministry, which they say makes it difficult for officials to identify any original virus carrier. Troedsson told Caijing that the bird flu issue is deeply linked to both animal hygiene and public health. For that reason, he said, more cooperation among government agencies is needed.

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