Pathologic manifestations of experimentally and naturally acquired lungworm infections in opossums.

Experimentally induced and naturally acquired lungworm infections (Didelphostrongylus and Capillaria) were studied in opossums, Didelphis marsupialis. Each of 4 helminth-free opossums were experimentally infected with 250 3rd-stage Didelphostrongylus hayesi larvae. At 2 and 8.5 months after infection, 2 animals were necropsied. Hypertrophy of pulmonary smooth muscle characterized D hayesi infections, with lesions pronounced in the vicinity of helminths. There was mucous bronchitis characterized by peribronchial gland hyperplasia, lymphoid nodule formation, and exudation of mucus and eosinophils into bronchioles. Lung from 4 opossums harboring natural infections of D hayesi or Capillaria or both was examined. Concomitant infections produced multifocal, indurated lesions often resulting in generalized consolidation. Microscopic examination revealed pulmonic damage consisting of hypertrophy of smooth muscle, extensive peribronchiolar adenomatoid hyperplasia of alveolar epithelium, and diffuse areas of granulomatous interstitial pneumonia. Capillaria provoked well-defined granulomas, and frequently only eggs and cuticular debris were contained within the lesions. Loss of pouch young by 1 naturally infected feamle was associated with extensive verminous pneumonia.