First detection of microsporidia in raised pigeons in Poland.

Microsporidia are single-celled intracellular parasites which occur in a number of animals, both vertebrates and invertebrates. Several species of microsporidia can cause disease in humans in both immunocompromised and immunocompetent individuals. However, the sources of human infection and the routes of transmission of microsporidia have not yet been fully determined, although more and more researchers are of the opinion that microsporidia in humans is zoonotic. The aim of the presented study was to identify the most common microsporidial species in the droppings of raised and wild pigeons in Poland. A total of 139 collective samples of droppings (33 samples of droppings from feral pigeons and 106 samples from raised pigeons) were examined using conventional staining and molecular techniques. Using chromotrope staining and multiplex FISH techniques, the microsporidial spores were found in 12 (8.6%) of the 139 samples of droppings. The spores of Encephalitozoon hellem were detected in five samples of pigeon droppings (3.6%), spores of E. intestinalis in four samples of droppings (2.9%), while spores of E. cuniculi and E. bieneusi were only detected in two samples (1.4%). Furthermore, a mixed infection of E. bieneusi and E. cuniculi was found in a single sample of droppings (0.7%). The presence of microsporidial spores in droppings collected from raised pigeons indicates a risk of infection to humans, mainly pigeon fanciers.