RESUMO
Pneumocystis spp. are thought to adapt to the lungs of potentially all mammals. However, the full host range, fungal burden and severity of infection are unknown for many species. In this study, lung tissue samples originating from 845 animals of 31 different families of eight mammal orders were screened by in situ hybridization (ISH) using a universal 18S rRNA probe for Pneumocystis, followed by hematoxylin and eosin (H&E) staining for determining histopathological lesions. A total of 216 (26%) samples were positive for Pneumocystis spp., encompassing 36 of 98 investigated mammal species, with 17 of them being described for the first time for the presence of Pneumocystis spp. The prevalence of Pneumocystis spp. as assessed by ISH varied greatly among different mammal species while the organism load was overall low, suggesting a status of colonization or subclinical infection. Severe Pneumocystis pneumonia seemed to be very rare. For most of the Pneumocystis-positive samples, comparative microscopic examination of H&E- and ISH-stained serial sections revealed an association of the fungus with minor lesions, consistent with an interstitial pneumonia. Colonization or subclinical infection of Pneumocystis in the lung might be important in many mammal species because the animals may serve as a reservoir.
RESUMO
Aim of this study was the retrospective investigation of viral (porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV), torque teno sus virus type 1 and 2 (TTSuV1, TTSuV2)) and bacterial (Bordetella bronchiseptica (B. b.), Mycoplasma hyopneumoniae (M. h.), and Pasteurella multocida (P. m.)) co-infections in 110 Pneumocystis spp. positive lung samples of Austrian pigs with pneumonia. Fifty-one % were positive for PCV2, 7% for PRRSV, 22% for TTSuV1, 48% for TTSuV2, 6% for B. b., 29% for M. h., and 21% for P. m. In 38.2% only viral, in 3.6% only bacterial and in 40.0% both, viral and bacterial pathogens were detected. In 29.1% of the cases a co-infection with 1 pathogen, in 28.2% with 2, in 17.3% with 3, and in 7.3% with 4 different infectious agents were observed. The exposure to Pneumocystis significantly decreased the risk of a co-infection with PRRSV in weaning piglets; all other odds ratios were not significant. Four categories of results were compared: I = P. spp. + only viral co-infectants, II = P. spp. + both viral and bacterial co-infectants, III = P. spp. + only bacterial co-infectants, and IV = P. spp. single infection. The evaluation of all samples and the age class of the weaning piglets resulted in a predomination of the categories I and II. In contrast, the suckling piglets showed more samples of category I and IV. In the group of fattening pigs, category II predominated. Suckling piglets can be infected with P. spp. early in life. With increasing age this single infections can be complicated by co-infections with other respiratory diseases.