3 Dec 2009
The latest surveillance indicators have shown a slight increase in human swine influenza (HSI) activity but it is too early to say whether we are looking at the second wave of HSI, a spokesman for the Department of Health's Centre for Health Protection (CHP) said today (December 3).
In the week commencing November 22, 2009, there were 135 influenza detections, compared with 60 in the previous week, of which 93 per cent were HSI virus. The attendance due to influenza-like illness (ILI) at designated flu clinics was 1,432 as compared with 786 in the previous week.
The sentinel surveillance at private clinics in the same week saw ILI attendance at 50.2 per 1,000 consultations, compared with 44.8 in the previous week. During the week, the CHP also recorded 12 ILI outbreaks as compared with eight during the week before.
Commenting on the slight rise in HSI activity, the spokesman said: "It is still early to conclude whether we have entered the second wave of HSI. The CHP is closely monitoring the activity in the coming weeks and will alert the public again if a definite increase in activity is observed."
Meanwhile, a systematic study of 269 virus isolates, including virus isolates from 29 fatal cases in Hong Kong, has revealed four more cases with the same mutation as found in Norway recently. The four cases included two fatal ones, bringing to five the total number of Norwegian mutations detected by the CHP in Hong Kong. The gene sequence from the other 27 fatal cases did not show the same mutation.
One of the patients who died, a 37-year-old Filipina who came to Hong Kong from the Philippines on June 28, 2009 and developed respiratory symptoms on the same day, passed away on July 27. The other, a 40-year-old lady who developed respiratory symptoms on September 6,2009, passed away on September 9. The other three patients had fully recovered.
"Currently, according to WHO, no evidence so far suggests that these mutations lead to an unusual increase in the number of HSI infections or a greater number of severe or fatal cases," the spokesman said.
"The Public Health Laboratory Centre of CHP has been monitoring influenza viruses worldwide and will remain vigilant against any further changes in the virus that may have public health significance."