Taiwan reported the world's first human case of H6N1 bird flu infection yesterday but appealed for calm, saying no sign of human-to-human transmission had been detected.
The patient, a 20-year-old woman who worked at a breakfast shop in Changhua county, central Taiwan, was admitted to hospital on May 8 with a high fever and respiratory problems, health officials said.
They said X-rays showed she was suffering from slight pneumonia, and the woman recovered and left the hospital on May 11 after being treated with anti-bird-flu medication.
The hospital told the health authorities on May 20 that it had been unable to determine the type of virus.
"We received the hospital's report," Chou Jih-haw, deputy director of the island's Centres of Disease Control, said in Taipei yesterday, and after further examination of the samples and comparison of the genetic sequence, the centres found the patient had the H6N1 flu strain.
H6N1 is a mild form of flu that has been found only in wild birds or in poultry in the past 15 years.
As it did not kill poultry and birds had a natural resistance to it, the virus was not listed as one that required reporting to the World Health Organisation, health officials said.
It is third bird flu strain to emerge in humans in China.
Another strain of bird flu, H5N1, first jumped the species barrier in Hong Kong in 1997 and has since killed more than 380 people worldwide. And this year H7N9 began infecting people on the mainland, and has killed 37 of 133 people infected.
Chou said the centres were trying to find out how the patient was infected, because she had never been abroad and had no history of contact with poultry. He said the Centres of Disease Control had reported the case to the WHO.
He appealed to the public to remain calm, saying the Centres of Disease Control checked 36 people who had been in contact with the patient and found that none had the H6N1 virus.
Dr Chuang Jen-hsiang, director of the Centres of Disease Control's epidemic department, said: "There has been no report or evidence of person-to-person transmission in this case."
Quarantine officials said they had collected samples from two poultry farms near the patient's home, but no H6N1 virus was detected. They ordered poultry farmers in Taiwan to implement strict sanitation controls.
Some Taiwanese experts suspect the infection could have been caused by the patient's everyday contact with eggs.
Hong Kong health experts said the human infection in Taiwan was an isolated case.
H6N1 has been found in fowl and quail in Hong Kong and other areas before, but University of Hong Kong microbiologist Dr Ho Pak-leung said the risk of infection was lower now because ducks and geese are no longer sold in the city's wet markets.
The concern now, he said, was whether there were more H6N1 human infections, what the source and route of transmission were, and whether there was any human-to-human transmission. For the time being, travellers did not need to worry about going to Taiwan as long as they did not visit farms or markets, he said.
Professor Paul Chan Kay-sheung, head of microbiology at Chinese University, said H6N1 did not usually make birds ill, but it could mutate to become highly pathogenic.