Pneumocystis spp. in Pigs: A Longitudinal Quantitative Study and Co-Infection Assessment in Austrian Farms

Meta-Analysis and Systematic Literature Review of the Genus Pneumocystis in Pet, Farm, Zoo, and Wild Mammal Species

A systematic literature search on Pneumocystis in 276 pet, farm, zoo, and wild mammal species resulted in 124 publications originating from 38 countries that were analyzed descriptively and statistically, for which inclusion and exclusion criteria were exactly defined. The range of recorded Pneumocystis prevalence was broad, yet in half of the citations a prevalence of ≤25% was documented. Prevalence was significantly dependent on the method used for Pneumocystis detection, with PCR revealing the highest percentages. Pet animals showed the lowest median Pneumocystis prevalence, followed by farm, wild, and zoo animals. In contrast, pet and farm animals showed higher proportions of high-grade infection levels compared to zoo and wild mammals. Only in individual cases, all of them associated with severe Pneumocystis pneumonia, was an underlying immunosuppression confirmed. Acquired immunosuppression caused by other diseases was frequently discussed, but its significance, especially in highly immunosuppressive cases, needs to be clarified. This meta-analysis supported a potential influence of the social and environmental factors of the host on Pneumocystis transmission in wildlife, which must be further elucidated, as well as the genetic diversity of the fungus.

Detection of Pneumocystis and Morphological Description of Fungal Distribution and Severity of Infection in Thirty-Six Mammal Species

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.

Clinical Efficacy of Two Novel, Differentially Administered (IM, ID) Vaccines against Mycoplasma hyopneumoniae and PCV2 in Swine under Field Conditions

Enzootic pneumonia (EP) of pigs is caused by Mycoplasma hyopneumoniae (M.hp.), which is, together with the porcine circovirus type 2 (PCV2), among the most prominent inducers of the porcine respiratory disease complex (PRDC). Therefore, vaccination of piglets against M.hp. and PCV2 is crucial in the fight against pulmonary infections. In this field study, we tested the clinical efficacy of two novel vaccines, one delivered IM (Hyogen^® + Circovac^®) and the other ID (MHyo-Sphere^®PCV ID), on a fattening farm in Lower Austria with a history of still ongoing EP. Average daily weight gain, coughing/sneezing index, losses due to morbidity/mortality, and lung scoring data at slaughter by means of CLP (Ceva Lung Program) were recorded for three consecutive fattening cohorts to achieve a powerful number of animals, one half each vaccinated with the IM vaccine and the other half with the ID vaccine (n = 659 in total). No statistically significant differences could be observed between the two vaccination groups for the parameters investigated, but the total median EP score, which categorizes pulmonary lesions due to infection by M.hp. with a theoretical range of 0-28, was lowered from initially 1.9 to 1.0, indicating that both vaccines proved very suitable measures in the fight against EP.

Maintenance of gut microbiome stability for optimum intestinal health in pigs - a review

Pigs are exposed to various challenges such as weaning, environmental stressors, unhealthy diet, diseases and infections during their lifetime which adversely affects the gut microbiome. The inability of the pig microbiome to return to the pre-challenge baseline may lead to dysbiosis resulting in the outbreak of diseases. Therefore, the maintenance of gut microbiome diversity, robustness and stability has been influential for optimum intestinal health after perturbations. Nowadays human and animal researches have focused on more holistic approaches to obtain a robust gut microbiota that provides protection against pathogens and improves the digestive physiology and the immune system. In this review, we present an overview of the swine gut microbiota, factors affecting the gut microbiome and the importance of microbial stability in promoting optimal intestinal health. Additionally, we discussed the current understanding of nutritional interventions using fibers and pre/probiotics supplementation as non-antibiotic alternatives to maintain microbiota resilience to replace diminished species.