Are zoonotic protist parasites present in the English urban environment?

Giardia duodenalis (syn. G. lamblia and G. intestinalis) and Entamoeba spp. are intestinal protozoa capable of infecting a range of animal species. Giardia has potential to contaminate water and food, whereas E. histolytica can cause amoebic disease. From a public health perspective, these protozoan parasites have high zoonotic potential being among the most common intestinal human parasites worldwide. The main aim of this study was to evaluate if Giardia and Entamoeba are present in an English urban environment (Leicester) and to determine if public health interventions are necessary to protect human health. Thus, fourty-six fresh animal faecal samples were collected from Humberstone and Abbey Park (Leicester) in August and November 2017, respectively. A veterinarian identified the possible animal species as: 28 avian (2 songbird, 2 pigeon, 19 waterfowl, 5 uncertain), 14 dog and 4 cat. Smears were stained with trichrome as described elsewhere. Entamoeba spp. was not detected in any of the monitored samples. Conversely, Giardia spp. cysts were observed in three faecal samples from dogs (21.4% dog; 6.5% faecal samples), confirming our previous results in which we detected the presence of G. duodenalis in one dog faecal sample collected in Leicester’s Castle Park (central Leicester) in a pilot study performed in winter 2016 using the immunoassay ImmunoCard STAT!®. Our results, although preliminary, indicate the presence of Giardia spp. in Leicester’s urban environment. Moreover, dogs could act as reservoirs and might play a potential role in the transmission of these pathogens in Leicester as they could intermittently excrete cysts in their faeces, which can remain viable and infective in the environment for several months. Thus, a more comprehensive study to determine the size of this risk and the necessity of enhancing public health awareness to reduce canine faecal pollution in Leicester is necessary to protect human health.