Using Host-Specificity of &amp;lt;i&amp;gt;Cryptosporidium&amp;lt;/i&amp;gt; to Understand Contaminant Sources, Seasonality, and Human Health Risk in Three Watersheds of Differing Land-Use

Janis L Thomas,Katarina D M Pintar,Peter M Wallis,Norman F Neumann

doi:10.4236/jep.2016.73033

Abstract

Three tributaries of the Grand River watershed (Ontario, Canada), each representing different watershed types (urban, agricultural/rural, and mixed land-use) were examined to understand the spatial, temporal, and host-source distribution of the waterborne pathogen, Cryptosporidium. Cryptosporidium was frequently found throughout the study (73%, 65/89) with occurrence and concentrations observed to be similar among the varying watershed types. However, applying advanced genotyping techniques, marked differences in dominant host sources could be observed in each watershed. The agricultural/rural and mixed land-use watersheds were dominated by genotypes typically associated with cattle (i.e., C. andersoni), while the urban watershed had the highest diversity of Cryptosporidium genotypes with a variety of wildlife as the common source of contamination (e.g., muskrat and cervine genotypes). A similar seasonal trend observed in the urban, agricultural, and mixed land-use watershed suggests that factors beyond specific land use activities (e.g. autumn manure spreading) may influence the timing and concentration of Cryptosporidium in these streams. Corresponding genotyping results provided additional insight into source inputs during these seasonal peaks, indicating that wildlife may be important seasonal contributors to Cryptosporidium contamination in these streams. Despite the abundance of Cryptosporidium in these watersheds, most of the genotypes observed were of limited human health importance. This study provides evidence regarding the significance of including genotyping results into studies examining waterborne Cryptosporidium. Using this technique can provide a greater understanding of the risk to the population using water sources, as well as provide insight into the probable sources and timing of contamination. This ancillary information can contribute to implementation of targeted management strategies to further protect sources of drinking water and recreation areas.

Highlights

Cryptosporidium is a well-recognized waterborne pathogen that has been implicated in drinking water and recreational water outbreaks in North America and around the world [1]-[4]
This study demonstrated that Cryptosporidium was ubiquitous in watersheds that were impacted by a range of land-uses, including urban, agricultural, and mixed land uses
Occurrence data alone could not determine the potential sources of Cryptosporidium; applying advanced molecular genotyping analysis proved to be a useful tool for understanding the dominant sources of Cryptosporidium in each watershed, as well as provided greater insight into seasonal contaminant sources

Summary

Introduction

Cryptosporidium is a well-recognized waterborne pathogen that has been implicated in drinking water and recreational water outbreaks in North America and around the world [1]-[4]. Agricultural animals, cattle, are well recognized as a source of Cryptosporidium [4]-[7]. A wide range of host animals can be infected and excrete Cryptosporidium in their feces, including domestic animals, various wildlife, and humans [6] [8]-[11]. Given the host range of Cryptosporidium, many fecal sources can be a source of contamination to water, including sewage treatment discharges, run-off from cropland following manure application, and direct access of domestic and wild animals to water sources. Many Cryptosporidium species are host-adapted, meaning that they infect certain types of animals over others. Two species of Cryptosporidium are primarily responsible for human infections: C. hominis and C. parvum. C. parvum is less host-adapted and can infect a range of animals including humans and cattle [12]-[14]

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