Re-assessing the public health risk associated with the waterborne transmission of Cryptosporidium spp.

Cryptosporidium is a faecally transmitted parasite and an aetiologic agent of human enteric disease worldwide. Contaminated food, water, and direct contact with infected animals have long been considered risk factors for parasitic infection. The applications of molecular diagnostic tools in clinical and environmental research settings have inspired a new understanding of Cryptosporidium taxonomy and disease transmission. Once thought to be a non-specific parasite with a broad host range, cryptosporidia are now considered to be relatively host specific, bringing into question the true zoonotic potential of this parasite. Contaminated water is considered a major risk factor contributing to outbreaks of human cryptosporidiosis. In light of Cryptosporidium host-specificity and the expanding complexity associated with the molecular epidemiology of this parasite, the ability to differentiate the various species and genotypes of Cryptosporidium from environmental water samples becomes imperative. These emerging concepts need to be integrated into the risk assessment strategies used to associate the public health impact of water supplies contaminated with Cryptosporidium spp. (c) 2006 Lippincott Williams & Wilkins.