Report on avian influenza in the Eastern Hemisphere during 1997-2002.

Since the Fourth International Symposium on Avian Influenza (AI) there has been considerable AI activity in the Eastern Hemisphere. The higher profile of AI resulting from the human infections with H5N1 and H9N2 viruses in Hong Kong, in 1997 and 1999, respectively, resulted in increased reporting and active surveillance. There have been three reported incidents of high-pathogenicity (HP) AI: H5N2 in northeastern Italy in 1997 (eight outbreaks); H5N1 in Hong Kong in 1997 recurring in 2001 and 2002; H7N1 in northeasten Italy resulting in 413 outbreaks in 1999-00. The Italian HPAI outbreaks were preceded by 199 H7N1 low-pathogenicity (LP) AI outbreaks in 1999, and this virus continued to cause some problems after the eradication of HPAI. During the second half of the 1990s outbreaks of LPAI due to H9N2 subtype have been reported in Germany, Italy, Ireland, South Africa, Hungary, Korea, China, Hong Kong, countries of the Middle East, Iran, and Pakistan. The continued presence of virus of this subtype in the Middle and Far East may mean it is becoming an established endemic disease in those regions. Other more restricted outbreaks in poultry have resulted in the isolation of LPAI viruses of H5, H6, H7, and H10 subtypes.