Immunohistochemical and ultra-structural detection of Pneumocystis in wild boars (Sus scrofa) co-infected with porcine circovirus type 2 (PCV2) in Southern Brazil.

Pneumocystis spp. are fungi that are able to infect a variety of host species and, occasionally, lead to severe pneumonia. Porcine circovirus type 2 (PCV2) is an important viral pathogen which affects both swine and wild boar herds worldwide. Co-infection between PCV2 and other pathogens has been reported, and the secondary immunodeficiency caused by the virus may predispose to these co-infections. In the present study, postmortem tissue samples obtained from wild boar herds in Southern Brazil were analyzed by histopathology, ultra-structural observation, and immunohistochemistry. Forty-seven out of seventy-eight (60%) wild boars showed clinical signs, gross, and histopathological lesions characteristic of infection by PCV2. Pneumocystis was detected by immunohistochemistry in 39 (50%) lungs and viral antigens of PCV2 were found in 29 (37.2%) samples. Concomitant presence of Pneumocystis and PCV2 were observed in 16 (20.5%) of the wild boars. Cystic and trophic forms of Pneumocystis were similar to previously described ultra-structural observations in other mammals.