Suitability of specimen types for isolation of avian influenza viruses from poultry.

In view of the outbreaks of the highly pathogenic avian influenza (HPAI) H5N1 virus in poultry in India, its impact on global public health and growing concerns of avian influenza (AI) viruses, surveys in wet poultry markets were conducted in the states of Maharashtra, West Bengal and Jharkhand in India during the period 2009-2012. During these surveys various types of samples from poultry were collected. During outbreaks and surveys in poultry, tracheal swabs (TS), cloacal swabs (CS), poultry drinking water (PDW) samples and fecal samples (FS) are preferred samples for AI diagnosis. The suitability of various types of poultry samples for AI virus isolation was analyzed. The parameters such as availability of specimen, ease of collection, quality of the specimen for the presence of contaminants such as organic debris or solid matter were considered for the analysis. A total of 2,405 samples were collected, which included 1,297 TS, 1,012 CS, 79 PDW, and 17 FS. Out of 2,309 TS and CS samples 1,752 samples were paired samples, collected from 876 birds. All samples were processed for virus isolation and identification. Of the 2,405 samples AI H9N2 was isolated from 199 samples (8.27 %). The virus isolation rate was significantly higher in PDW samples (21.5 %) (P < 0.05) and TS samples (12.1 %), in comparison with CS (2.3 %) (P < 0.001). Other viruses isolated were AI H4N6 and HPAI H5N1viruses; however the number of isolates of AI H4N6 and H5N1 were not sufficient for comparison. In conclusion, the PDW and TS samples were suitable for AI H9N2 virus isolation from poultry.