Lesions caused by Diplotriaena tricuspis (Nematoda: Diplotriaenoidea) in the American crow, Corvus brachyrhynchos Brehm

Lesions in crows (Corvus brachyrhynchos Brehm) experimentally infected with Diplotriaena tricuspis (Fedtschenko, 1874) Henry and Ozoux, 1909 were studied. Larvae caused traumatic lesions during their movements through the hepatic portal system. Giant cell granulomas surrounded dead nematodes in the liver and its capsule. Some eggs were encapsulated in the hepatic capsule and subcapsular parenchyma. Chronic liver inflammation, including lymphoid hyperplasia, occurred.Various pulmonary lesions developed, including oedema, fibroplasia, infiltrations, haemorrhage, periarteritis, endothelial swelling and vacuolation, lymphoid hyperplasia, congestion, and thrombosis. Giant cell granulomas, containing living and dead nematodes, occluded parabronchi and secondary bronchi. Pulmonary inflammation persisted although most live D. tricuspis had moved into the air sacs by 45 days. Aspirated eggs evoked granulomatous pneumonia and mucoid hyperplasia of bronchiolar epithelium.In air sacs a few live D. tricuspis were surrounded by an acute inflammatory reaction. Dead nematodes were enclosed in giant cell granulomas. Rarely, air sacs were discoloured and roughened, and excess frothy fluid was present. Eggs encapsulated in fibrous tissue in the wall of air sacs were noted. Clinical signs were observed in only 1 of 44 experimentally infected crows.