Cryptosporidium is a single-celled parasite which infects the epithelial cells of the small intestines leading to cryptosporidiosis.
Symptoms include diarrohoea, vomitting, stomach cramps and fever.
Symptoms last for 2 weeks in healthy people.
In immuno-suppressed people (eg. with AIDS or the elderly) it's more serious.
No effective treatment.
Spread of Cryptosporidium
Cells of Crypt. leave the gut as oocysts in the faeces.
Oocysts are resistant to environmental changes and can lie dormant for many months in cool, damp conditions. If ingested they infect the new host.
Slurry from infected farm animals and sewage with faeces from infected humans can carry oocytes to rivers used for drinking water abstraction.
Outbreaks occur when water is still contaminated with oocytes after passing from the water treatment plant into drinking water supply.
Most water treatment plants cannot completely remove them because they are very small and resistant to the levels of chlorine used.
Levels of Crypt. can be kept to a minimum by limiting the contamination from slurry and sewage, the use of ultra-filtration and ozone to purify water, careful maintenance of water treatment systems.
The guideline for notifying of an outbreak is one in every 10 liters of water.