Protozoan

In the summer of 2007, 6 fatal cases of infection occurred in the United States, all young males (Medscape)

Giardiasis is not associated with mortality except in rare cases of extreme dehydration, primarily in infants or malnourished children (Medscape)

Case fatality rates associated with amebic colitis range from 1.9%-9.1% (Aristizábal et al, 1991)

Cryptosporidium parvum causes cryptosporidiosis, a parasitic infection. The symptoms of cryptosporidiosis are: watery diarrhea, stomach cramps, dehydration, nausea, vomiting, fever, and weight loss. In healthy people, the disease created by the parasite is self-limiting, but in immunosuppressed individuals, the disease may be chronic and severe.

C. hominis causes the disease, Cryptosporidiosis. The symptoms are: diarrhea, vomiting, anorexia, fever, and abdominal cramping. The respiratory system can be affected as well. It is usually self-limiting, but can be harmful to immunocompromised individuals.