Patho-epidemiology of respiratory disease complex pathogens (RDPs) in commercial chicken
*Corresponding author: e-mail: karam.singh@rediff mail.com
Respiratory disease complex (RDC) has emerged as a challenge to poultry industry. A total of 534 chicken suspected to have died of respiratory disease caused by pathogens such as Newcastle disease virus (NDV), infectious bronchitis virus (IBV), low pathogenic avian influenza virus (LPAIV), infectious laryngotracheitis virus (ILTV), metapneumovirus and fowl adenovirus infections (FAdV), Es-cherichia coli, Pasteurella multocida, Avibacterium paragallinarum, Ornithobacterium rhinotracheale (ORT) and Mycoplasma gallisepticum (MG) were screened by polymerase chain reaction and the pathological lesions were characterized. Of these 534 chickens with respiratory pathology, 457 (85.58%) were found to be positive for at least one of the screened pathogens. Among these 457 positive cases, 227 (48.67%) cases revealed infection by single screened pathogen (monoinfection), while 230 samples (50.33%) had concurrent infections by two to five pathogens in a single case. Among different pathogens, NDV could be detected in 265 cases (57.99%) either as single infecting agent or in combination with other viral or bacterial pathogens, followed by LPAI-H9N2 in 132 cases (28.88%), E. coli in 115 cases (24.95%), respiratory mycoplasmosis in 82 cases (17.94), infectious bronchitis in 47 cases (10.28%), infectious laryngotracheitis in 35 cases (7.66%), FAdV infection in 8 cases (1.75%), fowl cholera in 7 cases (1.53%), and ornithobacteriosis in 3 cases (0.66%). From these fi ndings it was concluded that concurrent infections by several genotypes of NDV, H9N2 strain of AIV-A, IBV, E. coli and MG are the leading cause of respiratory disease complex in chicken, while pathogens such as ILTV, FAdV and ORT are emerging as potential threat to poultry industry.
Chicken, concurrent infections, pathology, respiratory disease complex.