Cryptosporidiosis

Cryptosporidiosis
Micrograph showing cryptosporidiosis. The cryptosporidium are the small, round bodies in apical vacuoles on the surface of the epithelium. H&E stain. Colonic biopsy.
Classification and external resources
Specialty	infectious disease
ICD-10	A07.2
ICD-9-CM	007.4
DiseasesDB	3221
MedlinePlus	000617
eMedicine	med/484
Patient UK	Cryptosporidiosis
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Cryptosporidiosis, also known as crypto, is a parasitic disease caused by Cryptosporidium, a genus of protozoan parasites in the phylum Apicomplexa. It affects the distal small intestine and can affect the respiratory tract in both immunocompetent (i.e., individuals with a normal functioning immune system) and immunocompromised (e.g., persons with HIV/AIDS or autoimmune disorders) individuals, resulting in watery diarrhea with or without an unexplained cough. In immunocompromised individuals, the symptoms are particularly severe and can be fatal. It is primarily spread through the fecal-oral route, often through contaminated water; recent evidence suggests that it can also be transmitted via fomites in respiratory secretions.

Cryptosporidium is the organism most commonly isolated in HIV-positive patients presenting with diarrhea. Despite not being identified until 1976, it is one of the most common waterborne diseases and is found worldwide. The parasite is transmitted by environmentally hardy microbial cysts (oocysts) that, once ingested, sporozoites within oocysts excyst (i.e., are released) and result in an infection of intestinal epithelial tissue.

Cryptosporidiosis may occur as an asymptomatic infection, an acute infection (i.e., duration shorter than 2 weeks), recurrent acute infections in which symptoms reappear following a brief period of recovery for up to 30 days, and a chronic infection (i.e., duration longer than 2 weeks) in which symptoms are severe and persistent. It may be fatal in individuals with a severely compromised immune system.Symptoms usually appear 5–10 days after infection (range: 2–28 days) and normally last for up to 2 weeks in immunocompetent individuals (i.e., individuals with a normal functioning immune system); symptoms are usually more severe and persist longer in immunocompromised individuals (e.g., persons with HIV/AIDS). Following the resolution of diarrhea, symptoms can reoccur after several days or weeks due to reinfection. Based upon one clinical trial, the likelihood of re-infection is high in immunocompetent adults.

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