Prevalence and Pathology of Lung Worm Infection in Sheep in Kashmir Valley, India

The study was conducted in the Kashmir Valley with the aim of determining prevalence and pathology of lung worm infection in indigenous sheep. A total of 1455 slaughtered or spontaneously dead sheep were screened. The overall prevalence of lung worm infection was found to be 26.6%. Age, sex and body condition were taken as risk factors for the occurrence of lung worm infection. Prevalence of 40.68% and 16.37% were observed in sheep of age groups < 1 years and > 1 years, respectively. There was no significant (P < 0.05) difference in the prevalence among male and female sheep. However, the prevalence was significantly (P < 0.05) the higher in those sheep with emaciated body conditions than in those with relatively good body conditions. On the basis of morphological characteristics the most adult worms were identified as Dictyocaulus filariae. Histopathological examination of affected lungs revealed bronchitis and bronchiolitis with desquamation of epithelial cells in the lumen of bronchiole. Cross sections of the adult nematodes were demonstrated in the bronchi and bronchiole. At places, pneumonic areas with mononuclear cell infiltration and peribronchiolar lymphoid hyperplasia were observed. The bronchial epithelium showed marked hyperplasia and desquamation and peribronchiolar and perivascular areas were infiltrated by inflammatory cells. Hyperplastic bronchiolar epithelium as well as parasitic sections in the bronchiole was positive for acid mucopolysaccharides. Disruption and disorientation of elstic fibres was also noticed. Hyperplastic epithelium revealed metachromasia and mast cell reaction was observed to be more pronounced in bronchial and peribronchial areas.