Annual presence and distribution of human-pathogenic {Acanthamoeba} spp. in River Soar, Leicester, UK

Abstract

BACKGROUND AND AIM: {Acanthamoeba} spp. can act as opportunistic parasites and are becoming a serious threat to human health due to the resistance of their cysts to harsh environmental conditions and water treatment practices. Owing to the lack of knowledge about {Acanthamoeba}'s epidemiology in England, the aim of the present work was to study, over one year, the presence and circulation of this opportunistic parasite in the River Soar, which crosses Leicester city (England) and attracts large numbers of users. METHODS: Water samples were collected from nine different locations following the course of the river through the city per season (n=45) from Summer 2017-Summer 2018, following protocol 1623 described by US EPA. Samples were concentrated using IDEXX® Filta Max system following manufacturer's instructions. DNA extraction from concentrated water was performed with FastDNA® Spin Kit. A triplex real-time TaqMan PCR assay was performed to detect {Acanthamoeba} spp., using established methodologies. RESULTS:{Acanthamoeba} spp. was detected in 17 water samples: 4 in each season from Summer to Winter 2017, two in Spring 2018 and three in Summer 2018. These free-living amoebas were discovered in each sampled location, which highlights a moderate to high circulation of {Acanthamoeba} in the River Soar throughout a year, without seasonality, despite significant changes in the water flow rate and temperatures recorded in the river and in Leicestershire. This river is rich in wildlife, which might play a role in the presence/circulation of {Acanthamoeba} spp. CONCLUSIONS:To our knowledge, this is the first report reporting the presence and circulation of {Acanthamoeba} spp. in an English river throughout a complete year. The presence of {Acanthamoeba} spp. in this river could represent a risk for human health, for example rowers, which is present throughout the whole year. Therefore, this risk should be tackled as the incidence of {Acanthamoeba} keratitis has increased in recent years in England. KEYWORDS: {Acanthamoeba} spp., River Soar, environmental presence, human risk.