Press Release WHO/1 6 January 1998   INVESTIGATION OF ORIGINS OF H5N1 INFLUENZA VIRUS STEPPED UP IN HONG KONG   There have now been 16 cases of H5N1 influenza in humans, while a further four are suspected. Of the 16 confirmed cases, six have already been discharged from hospital. Moreover, the rate of reporting of new cases has slowed down in the past week. Epidemiological studies centred around the confirmed cases in humans continue. In the light of recent developments, the World Health Organization (WHO), together with several of its Collaborating Centres for Influenza, has been focussing for the past two weeks on identifying the reservoir of H5N1 in poultry and animals. To date, over 1 850 samples have been taken from 12 species of birds and animal by a joint WHO/Hong Kong University team. The samples are currently being investigated for the presence of H5N1 virus and first results will be available within a few days. WHO headquarters and its Regional Office for the Western Pacific (WPRO), in close collaboration with, and at the request of, the Government of the People's Republic of China, will send a team of WHO officials and international experts to China within two weeks to discuss surveillance and control aspects of the H5N1 outbreak in Hong Kong. ADisease does not respect borders and intensified surveillance is an important step towards elucidating pathways of transmission of the H5N1 virus and the links between human disease and the animal reservoir,@ said Dr David Heymann, Director of WHO=s Division of Emerging and other Communicable Diseases Surveillance and Control (EMC). To date, there is still no clear evidence of human-to-human transmission. In the absence of any sign of such transmission no new measures, such as travel restrictions or quarantine, are warranted. Furthermore, no measures are currently warranted vis-à-vis cats and dogs in Hong Kong which may have come into contact with chickens, as cats and dogs are not known at present to carry or transmit the H5N1 virus.  Related stories: Low Levels of Exposure to H5N1 Influenza Virus Unlikely to Result in Infection (29 December, 1997) H5N1 Influenza Virus in Hong Kong, No New Measures Warranted (23 December, 1997) Influenza A(H5N1) in Hong Kong: Update (19 December, 1997) Influenza A(H5N1) in Hong Kong : Two New Suspect Cases (17 December, 1997) International Effort to Combat New Influenza Strain Stepped Up (15 December, 1997) WHO Confirms Second Case of New Flu Virus Strain in Humans (2 December, 1997) For further information, please contact Gregory Hartl, Health Communications and public Relations , WHO, Geneva. Telephone (+41 22) 791 4458. Fax (+41 22) 791 4859. Email hartlg@who.ch All WHO Press Releases, Fact Sheets and features as well as other information on this subject can be obtained on the Internet on the WHO home page at http://www.who.ch .