Description of the situation
13 April 1999
Disease Outbreak Reported
Further genetic analysis of the human virus isolates from 2 hospitalized children in Hong Kong SAR in March 1999, confirmed to be influenza A(H9N2) by the WHO Collaborating Centre for Influenza in London (United Kingdom) WHO Collaborating Centres in Atlanta (United States), has revealed that the viruses are genetically closely related to, but distinct from, influenza A/Quail/Hong Kong/GI/97(H9N2) isolates detected in 1997 during the influenza A(H5N1) outbreak in Hong Kong SAR.
Studies on the spread of A(H9N2) viruses between cages of chickens indicate that quail H9N2 virus is transmitted by aerosol more effectively than by faecal transmission.
In China, 5 human cases of influenza A(H9N2) were apparently identified in March 1999, but laboratory confirmation of the virus was not reported. Of the 5 cases, the youngest was 1 year old and the oldest was a man in his 70s. All patients apparently had mild influenza-like symptoms and recovered with no medical complications.