OUTBREAK OF EQUINE INFLUENZA AMONG HORSES IN HONG-KONG DURING 1992

Equine-2 influenza virus A (H3N8) infection occurred among vaccinated thoroughbred horses in Dong Kong during November and December 1992, Th e outbreak was unique in that it occurred among a large population sta bled under intensive conditions, It resulted in the postponement of se ven race meetings over a period of 32 days, The outbreak originated af ter the importation of horses 25 to 32 days before any clinical signs were reported. Vaccination did not prevent 75 per cent of the populati on from becoming infected, and half the infected horses developed clin ical signs, Vaccination did, however, contribute to reducing the morbi dity and the severity and duration of the clinical signs.