Pathomorphological and molecular diagnosis of Haemophilus parasuis in pigs of northern parts of India

Septicaemic diseases are the leading cause of mortality in piglets causing great economic loss to the porcine industry. Haemophilus parasuis, an important pathogen in piglets, is widely distributed in all pig rearing countries. Carrier pigs are considered as the major reservoir of H. parasuis and could be a significant source of infection leads to septicaemia and pneumonia in pigs. In this study, a total of 51 tissue samples from different outbreaks of septicaemia in and around Bareilly district of Uttar Pradesh state of India were evaluated for H. parasuis infection by PCR and histopathological examination. A total of 12 samples were found positive for H. parasuis on screening (12/51, 23.52%). On post mortem examination, the gross lesion in lungs, heart, spleen and brain indicated establishment of septicaemia and pneumonia. The predominant histological changes observed were fibrinous polyserositis and bronchopneumonia as compared to other tissue lesions such as splenitis, nephritis, myocarditis and meningitis. The involvement of lymph nodes and joints were also observed as an important finding of the H. parasuis infection. The study revealed H. parasuis is prevalent in Indian pigs and is responsible for large outbreaks of septicaemia. In this context, more studies targeting the H. parasuis are highly warranted to establish its pathology and pathogenesis among Indian pigs.