Cold weather puts health officials on alert for bird flu
Mary Ann Benitez and Ng Kang-chung
Migration patterns affected as chill could linger for months
Migratory birds passing through Hong Kong because of chilly weather on the mainland could increase the risk of bird flu in the city, experts have warned.
Persistent cold weather in the city could also heighten the risk for more flu-like illnesses. So far this winter, six birds have been confirmed to have died of the H5N1 influenza virus and two others are being tested. The figures compare with 17 birds infected from January to March last year.
A dead Oriental magpie robin found with H5 on Sunday at the wholesale poultry market in Cheung Sha Wan prompted a thorough cleansing and disinfection there yesterday.
Meanwhile, private doctors and government outpatient clinics had reported they detected an increase of influenza-like illnesses in the community in the three weeks to February 2, a consultant with the Centre for Health Protection, Chuang Shuk-kwan, said.
Infectious-disease specialist Lo Wing-lok said: 'Because the winter was mild last year, perhaps birds moved north. Now with the mainland so cold, it could force the birds to delay their journeys north.'
As a result, the city had seen more migratory birds with bird flu, increasing the risk to resident birds and then to poultry, he said. 'If poultry is infected, the risk to the human population will escalate,' Dr Lo said. 'We must try our best to prevent this from occurring.'
Chinese University professor of microbiology Paul Chan Kay-sheung said the activity of H5 viruses would remain high amid the cold weather.
'We will expect a few more infected birds in the coming few weeks because the weather will be like this for a while,' Professor Chan said.
He said that in the latest bird-flu find in Cheung Sha Wan, the government should investigate whether there were any loopholes in bio- security measures.
'The key is whether the bird had any chance to contact and spread the infection to live chickens in the market,' he said. 'We do not want live chickens to have any chance of having contact with these birds.'
The Observatory said yesterday that La Nina, a weather event that was believed to have contributed to the lingering cold in the city, could last for a further two to three months.
The cooling pattern, last recorded eight years ago, had resulted in a strong winter monsoon affecting much of China.
A cold weather warning has been in force in the city since January 24. Between then and yesterday, the mean minimum temperature at the Observatory was 9.9 degrees Celsius - the second-lowest during that period since records began in 1885.
The current La Nina event is characterised by a cooling of the sea surface in the central and eastern equatorial Pacific. Senior scientific officer Yeung King-kay said it was expected to continue through the first quarter of the year.
But he added: 'La Nina does not necessarily mean extreme cold. In seven of the 12 times when La Nina was recorded, the average winter temperatures in Hong Kong were normal or even slightly higher.'