Cryptosporidium

Cryptosporidium is a water born pathogen that is a protozoan pathogen that causes a diarrheal illness called cryptosporidiosis. It usually causes a mild to severe infection of the gastrointestinal system, including watery diarrhea, fever, abdominal cramps, nausea, and vomiting.
Cryptosporidium is transmitted through feces and capable of completing its life cycle within a single host, resulting in microbial cyst stages which are excreted in feces and are capable of transmission to a new host. While the parasite is usually transmitted by the fecal-oral route infection may be acquired in a number of other ways:
-from animals, particularly lambs and calves, through contact with their infected feces;
-person to person contact, which is considered especially relevant in child day-care centers;
-from contaminated raw foods, e.g. raw meat, unpasteurized milk, fruit and vegetables.
There are many different species of Cryptosporidium though the main vectors are:
C. parvum (species of frog found in Lesotho, South Africa, and Swaziland)
C. hominis (humans)
C. canis (dogs)
C. felis (cats)
C. meleagridis (foul I.e. turkey, chicken, pigeon, quail, pheasant)

Treatment
Infection can lasts for up to two weeks and in rare cases as long as a month. There is no reliable treatment for cryptosporidium enteritis; certain medications are sometimes used, but they usually have only temporary effects. Treatment is primarily supportive. Fluids need to be replaced orally. A lactose-free diet should be taken as tolerated. In rare situations, intravenous fluids may be required. Antibiotics are not usually helpful.

Drinking water
Cryptosporidium is extremely resistant to chlorination methods it has been found that it is susceptible to ozone treatment given a long enough contact time. slow sand filters, diatomaceous earth filter and membranes will remove 99% of Cryptosporidium . As with all other pathogens boiling your water is the most reliable way of removing cryptosporidium.