Pulmonary cryptococcosis and Capillaria aerophila infection in an FIV-positive cat

Abstract

A 12-year-old, FIV-positive, domestic longhair cat was presented with a history of sneezing and coughing during the previous seven months. On thoracic radiographs, a prominent bronchial pattern and three focal, opacified nodules were seen. Cytology of bronchoalveolar lavage fluid demonstrated spherical, capsulate, narrow-necked, budding yeasts within macrophages. Culture of the fluid yielded a heavy growth of Cryptococcus neoformans var neoformans. The serum latex cryptococcal antigen agglutination test titre was 158. The cat was treated with itraconazole and the cough resolved over a 5-month period but then recurred. Repeat thoracic radiographs showed resolution of the pulmonary nodules but a persistent bronchial pattern. Adult nematodes and ova with morphology characteristic of Capillaria aerophila were seen in bronchoalveolar lavage fluid and no yeasts were cultured from the fluid. The cryptococcal titre was zero. The lungworm infection was treated successfully with abamectin and the cough resolved. Immunosuppression related to FIV infection may have predisposed this cat to sequential respiratory tract infections.