[Cryptosporidiosis in humans. Review].

Cryptosporidiosis basically is a gastrointestinal infection caused by the coccidian protozoa Cryptosporidium. The infection is associated with diarrhea worldwide but it is most prevalent among children below 5 years of age in the undeveloped countries. It is an important Public Health problem. Infection in humans is usually with C. parvum. The parasite appears to be transmitted by a variety of mechanisms but zoonotic- and person-to-person transmission, and contaminated water appear to be the most important. The mechanism by which the coccidium causes diarrhea is unknown. The extent of the disease is mostly dependent on the immune status of the host. In immunocompetent persons, C. parvum may cause a short term diarrheal disease that resolves spontaneously; in immunocompromised patients, especially those with AIDS, produces a prolonged, life-threatening cholera-like disease. The diagnosis is generally made by detection of oocysts in stools by means of several concentration and staining procedures. Modified acid-fast and fluorescence stains are widely used. Immunofluorescent assays with Cryptosporidium-clonal antibodies have been developed to detect oocysts in stool specimens. Specific humoral antibodies have been detected by immunofluorescence and enzyme-linked immunosorbent assay techniques. Although an effective agent for Cryptosporidium is not available yet, promising results have been related to the immunotherapy. Vaccines are not available and the control and prevention of the infection is limited because of the environmentally resistant oocysts and the ignorance of all its possible transmission routes.