Objective: In order to monitor the present situation of Avian influenza virus (AIV) and Newcastle disease virus (NDV) in migratory waterfowls effectively, 158 tracheal and cloacal swab samples for wild birds were collected from Sanjiang natural reserve during migratory seasons in October 2005, April 2006 and October 2006.
Methods: Serial passages in specific pathogen free embryonated chicken eggs, haemagglutination activity (HA) text, hemagglutination inhibition (HI) text and RT-PCR detection were used to isolate and identify AIV and NDV.
Results: Twenty AIV isolates and 13 NDV isolates were collected in the test. Twenty AIV isolates were all from aquatic birds in October 2006, and among these isolates, 12 AIV subtypes were identified definitely, 11 subtypes were found in mallards-H2N2 (2/20), H2N6 (2/20), H3N4 (1/20), H3N6 (2/20), H3N7 (2/20), H3N8 (2/20), H6N2 (2/20), H11N2 (1/20), H11N3 (1/20), H11N5 (2/20), H11N6 (1/20), and 1 subtype was found in garganey-H5N2 (1/20). Thirteen NDV isolates were collected in all three migratory seasons from 5 different species of waterfowls, including mallard (8/13), bean goose (1/13), white-fronted goose (1/13), common teal (1/13) and mandarin duck (2/13).
Conclusion: The results indicated that mallard, which possesses huge population size and world wide distribution, could be considered one of the most important natural carrier of AIV and NDV and may have more important ecological significance on viruses transmission than other species of wild birds.