The most common symptom is diarrhea along with cramping abdominal pain, especially in the right side. The diarrhea can be profuse and watery. Infection can also cause loss of appetite and vomiting. In people whose immune systems aren't compromised, infection is either without symptoms or symptoms go away on their own, usually in 30 days. However, in young children and immunocompromised adults, infection can cause severe and lengthy illness.
Diagnosis is made by the identification of the parasite in fecal smears or by intestinal biopsy.
Cryptosporidiosis has recently been added to the list of infections that must be reported by doctors and other health-care providers to the New York City Department of Health. The primary way of getting infected is person to person via the fecal-oral route. Those at highest risk are young children, especially those in day care, those who engage in oral-anal sex, and close personal contacts of infected patients. Some outbreaks have been traced to water supply systems. Cryptosporidiosis was first found in a human in 1976.