Mystery surrounds 7th human infection
By Li Dapeng/Zhang Feng (China Daily)
Updated: 2005-12-31 07:03

China reported its seventh human infection of H5N1 bird flu on Thursday, but questions remain over where the virus actually came from.

The victim, surnamed Zhou, from Meilie District of Sanming City in East China's Fujian Province, had never been into contact with infected birds or poultry before.

All 66,172 poultry raised within 3 kilometres of Zhou's home had been immunized by December 5.

No bird flu outbreak had happened previously in the district, and no abnormal poultry deaths had been found since this autumn, local officials said.

Investigators tested and culled 230 poultry in the nearby area as soon as the case was reported, but no virus was found.

The infection source is still being investigated, the Ministry of Health said.

"Zhou is unlikely to have been infected from poultry," said Xu Longshan, honorary director of Fujian Provincial Disease Prevention and Control Centre.

Zhou, a 41-year-old female worker, died on December 21.

After undergoing a thymus tumour excision operation in mid-October, Zhou became weak and caught fever on December 6. She was treated in a local hospital two days later, with symptoms of continuous fever and pneumonia.

Tests on December 23 by the Chinese Centre for Disease Prevention and Control were positive for H5N1 virus.

The case was not reported until December 29 because experts could not explain how she caught the virus, an official of the Ministry of Health, who refused to be identified, told China Daily.

Those who had had close contact with the woman were tested, and they are all healthy.

Zhou's relatives said that she didn't like to eat chicken and duck, and she did not have close contact with or eat ill birds. Also, no outside visitors or patients came to the family around the time of possible infection.

She lived in an urban area with good sanitation conditions. The previous six cases were mostly reported in rural areas, where the victims had close contact with infected poultry.

The WHO office in Beijing has been informed about the case, but it is also quite confused about the infection channel, Roy Wadia, spokesman of the office, said.

In many of the other human cases on the Chinese mainland this year, it was only after a probe began that authorities realized there had been bird flu outbreaks in the area, Wadia noted.

This points to the challenges of the animal surveillance process.

"Chinese officials have acknowledged this and other challenges, and there is a commitment to improving the situation but change won't occur overnight," Wadia said.

(China Daily 12/31/2005 page1)