CLINICAL AND LABORATORY DIAGNOSES OF NEWCASTLE AND INFECTIOUS BURSAL DISEASES OF CHICKENS
Keywords:Clinical diagnosis, NDV, IBDV, HI, AGIDT, RT-PCR assay
A comparative study was conducted to compare the disease diagnostic parameters (clinical signs & postmortem findings, organism isolation, serological test and molecular method) used to diagnose the Newcastle disease (ND) and infectious bursal disease (IBD) during the period from March 2009 to February 2010 in the laboratory of the Department of Microbiology and Hygiene, Bangladesh Agricultural University (BAU), Mymensingh. A total of 187 sick and dead chickens (63 broilers and 124 layers) of different ages (1 week to >15 weeks) were collected from 12 selective poultry farms (4 broilers and 8 layers) of Mymensingh and Gazipur districts. Clinically, 7 (14.89%) of 63 affected broiler and 27 (30.68%) of 124 affected layer chickens were diagnosed as Newcastle disease (ND) whereas, 11 (23.4%) of 63 affected broiler and 6 (4.82%) of the 124 affected layer birds were diagnosed as IBD on the basis of clinical history, clinical signs and postmortem findings. Virus isolation from field samples was performed by inoculating each suspected sample into 10-day-old chicken embryos. Out of 34 ND suspected field samples, 26 (5 broilers and 21 layers) were positive for NDV isolation and 11 (8 broilers and 3 layers) of 17 IBD suspected field samples, were positive for IBDV isolation. For confirmatory diagnosis, virus detection was confirmed by serological tests (HI and AGID) and RT-PCR assay. Out of 34 clinically diagnosed ND field samples, 20 (5 broiler & 15 layer) were positive by RT-PCR assay and 15 (10 broiler & 5 layer) of 17 IBD suspected field samples, were positive by both AGIDT and RT-PCR assay. Of the 26 HA positive NDV suspected AF, 19 (4 broilers and 15 layers) were positive by both HI & RT-PCR assay whereas, 10 (7 broilers and 3 layers) of 11 IBDV isolation positive tissue suspension were positive by both AGIDT & RT-PCR assay in the laboratory. Therefore, it may be concluded that serological (HI & AGIDT) and molecular (RT-PCR) techniques which allow rapid identification of most of samples are the reliable, sensitive, specific and more accurate methods to detect the viruses for the confirmatory diagnosis of diseases.
Bangl. J. Vet. Med. (2010). 8 (2) : 131-140