Cryptosporidium oocysts in drinking water and recreational water

Abstract

Oocysts belonging to a wide variety of species and genotypes of Cryptosporidium are common in livestock, wild animals, and humans. Consequently, water is frequently contaminated through direct contact with infected animals and their waste, run-off from contaminated land, or structural and engineering failures in water conveyance, storage, or treatment facilities. Oocysts are resistant to chlorine disinfection at the concentrations typically applied during drinking water treatment but properly operated treatment plants that utilize filtration usually remove oocysts from source water with high efficiency. Nevertheless, waterborne Cryptosporidium continues to be a public health concern. Outbreaks have been linked to treated drinking water, but regulations enacted over the last decade, better watershed management, and operational improvements have led to a decline in drinking water related cryptosporidiosis in some countries. However, the same period has seen a marked increase in cryptosporidiosis outbreaks caused by contamination of recreational water, particularly swimming pools. This chapter reviews recent waterborne outbreaks of cryptosporidiosis, discusses oocyst prevalence in drinking water and recreational water, examines the risk of waterborne transmission, and describes the principal methods for detecting oocysts in water, including genotyping environmental oocysts.