Are human pathogenic free-living amoebae present in Leicester city’s environment (UK)?

The environmental presence and distribution of human pathogenic free-living amoebae (FLA) Acanthamoeba spp., Naegleria fowleri and Balamuthia mandrillaris, have been reported in different environmental compartments and geographical locations, as they do not require a host to complete their life cycle. However, information on the environmental distribution of these opportunistic pathogens in Europe remains unclear and mostly limited to water environments in certain European countries such as Spain or Poland. The main aim was to further study the potential environmental presence of these opportunistic pathogens in Leicester in environments other than water ecosystems but that could represent a risk to the public. Forty-five samples were collected in October 2018 (5 topsoil, 5 grass and 5 animal faecal samples) from three different and frequently visited urban parks in Leicester (Castle Gardens, Victoria Park and Newalk Park). Only fresh faecal samples were selected for this study and collected on days with no previous precipitation for at least two days. A veterinarian identified the possible animal species as: 7 avian (3 waterfowl, 4 pigeon) and 8 canine (dog or possibly fox). After appropriate pre-treatment, DNA was extracted from each sample using the Fast DNA® Spin kit, following manufacturer’s methodologies. A triplex real-time TaqMan PCR assay was performed for detecting FLA using positive controls for the three amoebae, using established methodologies. All 45 environmental and animal faecal samples assessed for FLA were negative. However, our results should be considered inconclusive as, although rare, several studies have reported an increase in AK in England in recent years, which might indicate not only the presence but also the distribution of these parasites. Further monitoring studies are required to understand the presence and circulation of FLA in the English environment, particularly for Acanthamoeba spp., to inform public health decisions to prevent future infections.