Prevalence and histopathological analysis of cystic echinococcosis in ruminants of District Narowal, Pakistan: focus on pulmonary involvement.

A total of 384 animals (sheep, goat, cattle, and buffalo) were examined for the presence of hydatid cysts only in the lungs. The lung tissue samples associated with the hydatid cyst were collected immediately after slaughter, followed by fixation in 10% formalin. The fixed tissue was subjected to paraffin embedding technique. Tissue sections of 5 microns were cut by microtome and stained using Harri's Haematoxilin and Eosin method. Overall, 13.80% of ruminants were found positive for lung infections with hydatid cyst. Only the sex of ruminants showed significant (P < 0.05) association with the infection of hydatid cyst in lungs. All other variables, such as species of ruminants, age, and months showed non-significant (P > 0.05) association. Pulmonary sections taken from infected animals revealed laminated membranes encased in a region with significant (P < 0.05) cellular infiltration (53.4 ± 7.9 µm2), primarily composed of lymphocytes, plasma cells, macrophages, and occasionally neutrophils, and eosinophils. In addition, significant (P < 0.05) epithelial disruption in the bronchioles (0.94 ± 0.05 µm2) and alveolar septa were also noticed in sections. These histopathological findings lead to the conclusion that pathological changes occur in the tissues surrounding the cyst as well as in areas more distant from the cyst.