Waterborne cryptosporidiosis: current status.

In the past ten years Cryptosporidium oocysts have been shown to be common contaminants of water, causing at least 19 waterborne outbreaks of cryptosporidiosis which have affected more than 427 000 individuals. Recommended methods for oocyst isolation and enumeration are time-consuming and inefficient and experts state that the absence of Cryptosporidium oocysts in drinking water can never be guaranteed. In the UK alone, a National Research Programme costing pound3 million has been undertaken. Here, Huw Smith and Joan Rose review the current status of knowledge and identify approaches taken by UK and USA Government regulatory bodies in order to reduce the likelihood of waterborne transmission.