Cryptosporidium
In a healthy population, infection results in acute diarrhea,
which lasts for 2-3 weeks. The parasite can be life threatening for
people who suffer from suppressed immune systems such as AIDS patients,
children, and the elderly. Since the common method of treatment for
cryptospordium is filtration and chlorine is ineffective, the Environmental
Protection Agency (EPA) requires that all public water supply systems serving
more than 100,000 connections to monitor for cryptosporidium.