December 16, 1997
Initial assessment made by the Special Working Group on Influenza A H5N1 noted an association with poultry in some of the cases under investigation, Director of Health, Dr Margaret Chan said at a press conference today (Tuesday).
She noted that genetic analysis of the H5N1 virus in the first four cases so far had shown avian gene sequences while laboratory results of the other cases were pending.
Information collected during the investigation of the first seven cases - six confirmed and one suspected - indicated that some patients had contacts with poultry before the onset of the disease while others had not.
"This points to the fact that the transmission of the virus both from bird-to-human and human-to-human are possible," Dr Chan said.
"However, the efficiency of transmission from human-to-human should not be high or there should be hundreds and thousands of such cases in the territory by now, according to past experience with other types of influenza. Thus, the present cluster of cases detected in Hong Kong had not reached epidemic proportions."
"While the mode of transmission requires further study, the Hong Kong Government is proactive and considers it necessary to introduce a number of preventive measures to protect public health.
"The Inter-departmental Co-ordinating Committee on H5N1 convened this morning came up with a plan of action including tightened control on import of chicken, enhanced surveillance in both man and poultry, as well as improvements in environmental hygiene in markets."
She said that the Hong Kong Health Authority had been working very closely with the World Health Organisation (WHO) and the Centres for Disease Control (CDC) in USA in dealing with the investigation and study of this new strain of Influenza A H5N1 strain in man.
As one of the 110 surveillance centres for the monitoring of influenza, Hong Kong had played a vital part in detecting this new strain of flu in human.
The Department of Health was currently conducting four epidemiological studies to ascertain the mode of transmission.
CDC was conducting further tests on genetic sequencing of the virus and also working at full speed on the development of a test for blood samples taken.
WHO would distribute H5N1 virus testing kits to all of its Collaborating Centres around the world shortly for surveillance purpose.
However, time and more cases were required to provide scientific evidence that could be used for drawing up conclusive findings.
In the meantime, a lot of work had been done by the Department of Health and experts in this field to provide data for scientific analysis.
Of the seven cases being analysed so far, all were tested positive by the Hong Kong Government Virus Unit. Six had been confirmed by the CDC while the remaining one was classified as "suspected" pending CDC's independent confirmation.
Two of these cases indicated exposure to poultry within the incubation period, but the histories of the remaining five cases were less clear.
"Over 550 interviews were conducted and 2 550 laboratory specimens were taken during the course of investigations."
Follow-up on patient contacts showed all those with flu like illness had recovered. Results of throat swabs taken from contacts in the first few cases were all negative while results for the last three cases were pending.
Test results on the more than two thousand blood samples which could shed more light on the form of transmission could not be confirmed pending development and refinement of test by CDC.
So far, two patients had fully recovered, one under treatment in satisfactory condition, two under treatment in critical condition and two died.
In the meantime, two more cases were classified as "suspected" by the Department of Health, making the total number of Influenza A H5N1 cases in human nine.
The two latest cases involved a two year old boy and a three year old girl who were cousins of a confirmed case (5 year-old girl).
They had mild symptoms only and were now receiving treatment in hospital. Their conditions were satisfactory.
Follow-up investigation of the two cases had already started. The public would be kept informed of the latest development.
On treatment for this new strain of flu, Dr Chan said amantadine was found to be an effective agent if used during the early stage. Such information had been made available to government doctors and private practitioners.
For the public, Dr Chan advised that the best way to combat influenza infection was to build up body resistance by having a proper diet with adequate exercise and rest.
"Good ventilation should also be maintained."
To prevent this avian flu, the public are advised to maintain good personal hygiene. They should wash their hands thoroughly after handling live poultry. They should also avoid coming into contact with of sick or diseased poultry.
But Dr Chan also pointed out that chicken cooked thoroughly were safe for eating.
Note to Editors:
A table distributed at the press conference showing the update of the seven cases will be sent through the GIS fax machine.