Experimental cryptococcosis in buffalo calves.

摘要

The pathogenicity and pathology of Cryptococcus neoformans infection in buffalo calves were investigated. Fourteen young male calves were divided into 2 groups (7 were treated with 8 mg/kg/day dexamethasone for 10 days and 7 were untreated; 5 animals from each group were each inoculated intratracheally with 10 X 106 parasites and the remaining 4 served as uninfected controls). One animal from each infected group was killed on days 7, 14, 30 and 60 pi and one animal from each uninfected group was killed on days 14 and 60 pi to study the progression of disease. Clinical signs were mild fever, nasal and ocular discharge and respiratory distress. Haematology revealed leukocytosis with initial neutrophilia and subsequent monocytosis. Varying gross lesions were observed in lungs, brain, lymph nodes and intestines. Interstitial pneumonia, mild hepatitis, enteritis and meningoencephalitis were the major histopathological findings. C. neoformans was demonstrated in nasal discharge and various tissue sections using special stains. Except for a greater involvement of the respiratory tract in immunosuppressed (dexamethasone-treated) animals, immunosuppression did not appear to have much effect in modulating the disease.