The cardinal symptom is diarrhea, which is typically watery, and accompanied by abdominal cramps, fatigue, nausea, and anorexia. Fever and vomiting may occur. Diarrhea tends to persist longer (median of 5 to 10 days) than that seen with other etiologies and may relapse. In industrialized countries, most cases are immunocompetent adults who experience a self-limited illness. In persons with HIV/AIDS, it is not until the CD4 count falls below ~100 cells/ mm3 that the risk increases for severe, unrelenting disease accompanied by malabsorption, weight loss, and high case fatality, although asymptomatic or mild infection can occur even in this group.
Shirley, D., Moonah, S., & Kotloff, K. (2012). Burden of disease from cryptosporidiosis. Current Opinion in Infectious Diseases, 25(5), 555-563.
Cryptosporidium is an Apicomplexan oocyst-forming protozoan, first recognized as a causative agent of gastroenteritis in 1976. It is one of the most common human enteropathogens worldwide, with young children living in developing countries and persons with HIV/AIDS experiencing more frequent and more severe illness sometimes complicated by malnutrition and long term impairment of physical fitness. Reported cases in industrialized countries are also rising due to the leading role that Cryptosporidium plays as a cause of waterborne outbreaks.