Crypto under the microscope at Anglian Water

When testing water supplies for Crypto it is often difficult to distinguish the organism from other microscopic particles, so borderline cases must always be regarded as positive.

Cryptosporidium: a thorn in the side of every water supply company

Cryptosporidium has become a common cause of acute gastrointestinal illness in recent years. There have been several outbreaks associated with contaminated drinking water, including an incident in Milwaukee, US, affecting 400,000 people in 1993. Several smaller incidents have occurred in the UK, including a 4-5,000 victim outbreak in Torbay in 1995.

A major problem in preventing contamination is that Cryptosporidium is highly resistant to chlorine. The hard shells of the oocysts protect Cryptosporidium from the environment but once ingested, body temperature, acid, trypsin and bile salts break down the shell to release four mobile sporozoites, which infect and irritate the lining of the gastrointestinal tract.

A major source of contamination is from infected farm animals and wildlife. Cryptosporidium oocysts can be easily washed from farmland into rivers and other water sources.