Presence and distribution of microsporidia, emerging human pathogens, in an English urban environment.

The rapid development and expansion of urban environments is occurring on a global scale resulting in new and unprecedented environmental hazards to human populations. Thus, humans are becoming exposed to emerging pathogens in urban environments that could present a potential health risk. Microsporidia have emerged as opportunistic infectious agents with a ubiquitous distribution, mainly affecting immune-deficient humans such as HIV-infected patients. However, their infections are increasingly reported in non-HIV immunocompromised patients such as organ transplant recipients, patients with cancer, diabetes, as well as in immune-competent children and the elderly. Thus, accidental ingestion of human-pathogenic microsporidia (Enterocytozoon bieneusi, Encephalitozoon spp.) spores while using recreational areas and urban parks could be a threat for humans that has been minimally investigated. We have detected, for the first time, the presence of human-related microsporidia spores in 2 out of 18 dog faecal samples collected in public parks from the centre of Leicester (UK) in January 2016 during a pilot study. Further investigation using 228 animal faecal samples collected randomly in parks and recreational areas across Leicester and surroundings was performed from June 2016 to February 2017. Stool samples were from domestic and wild animals: 91 deer, 88 avian (pigeons and waterfowl), 18 dogs, 5 fox, 4 herbivores (squirrel, rabbit) and 22 unidentified due to diarrhoea. Detection of microsporidia was performed by Weber’s Trichrome staining. Spores of Enterocytozoon bieneusi were observed in 9 samples from a range of animals including birds, deer, fox and dog; and Encephalitozoon spp. in 27 samples (14 deer, 8 avian, 1 dog, 4 unidentified). Positive samples are being confirmed with conventional PCR after extraction of DNA by bead disruption of spores using the Fast-DNA-Spin kit. To our knowledge, this is the first study showing the distribution of microsporidia in an English urban region and highlights a range of urban animals as potential reservoirs in the studied areas. Further research is critical to understand the circulation of these emerging human pathogens in the urban environment to identify applicable preventive, control and decontamination approaches for reducing their infections.