The Studies On The Epidemic Of Avian Influenza In China

Aiming at the two major migrating routs of wild birds in China, the ecological distribution and prevalence of avian influenza were studied based on the investigation and analysis of the occurring and relative influential factors of highly pathogenic avian influenza (HPAI), serology of free birds of HAPI areas were investigation and analysis, live stocks and poultries of some areas of Heilongjiang province were investigation and analysis, the HA gene of avian influenza virus A/Goose/XJYL/10/2003HA(H₅N₁)isolated from Xinjiang goose were cloned and sequenced, NS gene of avian influenza viruses (H₅N₁) isolated in Xinjiang were also cloned and sequenced. On the base of upper studies, epidemiology and space-time distribution of HAPI were analyzed, the risk assessing frame of HPAI were established, the space-time model of air temperature which influenced the transmission of HPAI virus were analyzed and constructed, Bio-Math model for immunity and prevalence of avian influenza were establish. Major conclusions:1. The occurring and prevalence of avian influenza have their inevitable causes. They often take place on the area of water, birds, forests or the migrating area of wild birds and surrounding environments.2. The space-time rules of HAPI were studied and the risk assessing frame of HPAI was established.3. The air temperature in 2004 when avian influenza prevailed in China was analyses. The results showed that the high risk areas were under change during the whole year, which moved from south to north in Jan to May. From Jun to Aug, most areas of China were at a lower risk with Qingnai-tibet Plateau exceptions. The hign risk areas moved from north to south in Sep to Dec. The spatial and temporal cnaracters of high risk areas had certain correlations with the avian influenza events in the 2004 AIV season in China.4. The Bio-Math model for immunity and prevalence of avian influenza were established.5. Serology of free birds on HPAI areas was investigated and analysis, results indicated that investigation were an effective way of prediction and warning of avian influenza out breaking in China by inspecting the avian influenza virus, and also were essential The detection of serology offered a distinct target for further analysis on molecular level.6. Serology of live stocks and poultries of some areas of Heilongjiang province was investigated and analysis, results showed that the transmission of avian influenza virus existed in livestock and poultry industry. Subtype H₅ of avian influenzza virus existed in water fowls and chicks, but subtype H₉ of avian influenza virus has been found in swine flocks.7. HA gene of avian influenza virus A/Goose/XJYL/10/2003HA (H₅N₁) isolated from Xinjiang goose were cloned and analyzed, revealed a high homology of HA gene between this experimental strain and some strains isolated from Guangdong, Hong Kong and Southeast Asia, and there was some character of HPAI near the enzyme site of amino acid. Analalysis of phylogenetic tree demonstrated the avian influenza viruses isolated in Xinjiang are on a new separate brancn originated from Eurasian Lineage.8. NS gene of subtype H₅N₁ of avian influenza viruses isolated from Xinjiang were cloned and analyzed, results snowed that the nucleotide and deduced amino acid among them were 97.8-98.9% and 96.5-99.4% homology, respectively. These strains have 90.0-99.4% identity with 11, avian influenza viruses isolated from Guangdong, Hong Kong and Southeast Asia. And there was 81.4-99.3% homology between stains isolated from Xinjiang and 11 avian influenza viruses isolated from wild poultries and swine. The phylogenetic analysis indicated the Xinjiang strains were on a new separate brancn.9. One H5N1 avian influenza virus strain was isolated from wild bird.