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The recent outbreak of cases of avian flu (avian influenza strain H5N1) has created a new interest in influenza. International public health organisations have stepped up their joint effort to combat the further spread of this virus in humans and its possible consequences.
Two main thrusts of action by the international health community are the preparation of seed virus for the eventual development of a vaccine for the H5N1 strain and increased surveillance activities in human and birds.
The World Health Organisation (WHO) Collaborating Centres for Influenza are working with various H5 strains to prepare seed virus in case a vaccine is needed. The eventual preparation of a vaccine strain may take several months, but in the absence of human-to-human transmission and of any documented outbreak, WHO is not recommending the development of a specific H5N1 vaccine. In the meantime, two antiviral drugs, amandatine and rimantadine, have been shown to be effective when taken in the early phase of illness.
Influenza surveillance in humans has also been intensified and now includes all hospitals and 63 public health clinics in Hong Kong, Special Administrative Region of China. A team of five epidemiologists from the WHO Collaborating Centre for Influenza Reference and Research at the Centres for Disease Control and Prevention (CDC), Atlanta, USA are on site for investigations. Blood samples are being collected from family members of the people infected, nursing staff and other contacts.
The H5N1 virus, formerly found only in fowl, has been isolated as the cause of nine confirmed cases of influenza in Hong Kong, Special Administrative Region of China, since May. Three of these cases have been fatal. There are an additional three suspected cases currently under investigation. This number is likely to increase slowly in coming weeks due to the enhanced surveillance activities now in progress.
Detection of new cases is probably the result of very comprehensive surveillance rather than an indication of increased transmission. The Department of Health in Hong Kong has stepped up its monitoring and surveillance activities. In addition to all hospitals and clinics in Hong Kong, a selected number of general medical practices are also now part of the surveillance system.
“The cases so far isolated come from all parts of Hong Kong and there is still no definite sign of human-to-human transmission. The cluster of cases which has been observed within a family does appear to have a common source and we are working to identify that,” said Dr Daniel Lavanchy of WHO’s Division of Emerging and other Communicable Diseases Control and Surveillance (EMC).
It is evident that the virus transmits poorly. WHO is assisting in the increased surveillance to search for any evidence of the infection in live chickens, and other animals such as rats, mice, dogs, cats and other domestic and wild birds, in Hong Kong and the vicinity.
Surveillance for the Influenza A (H5N1) virus is being carried out in Singapore. This strain of influenza virus has not been seen in Singapore among humans or poultry.
The Ministry of Health, Singapore, urges medical practitioners to be on a look-out for possible cases of the infection. Patients, in particular those who have recently travelled to Hong Kong, presenting with flu-like symptoms should be followed-up closely. Patients with severe acute respiratory infections should be referred immediately to the hospitals for management and virological investigations.
Source: WHO Press Release. 15, 17 & 23 Dec 97