<B>Cryptosporidiosis of Colon </B>

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Cryptosporidiosis of Colon

Etiology:

• Cryptosporidiosis is caused by the protozoan parasite Cryptosporidium parvum

Pathogenesis:

• The disease is acquired by ingestion of an oocyst
• Trophozoites are liberated and attach themselves to the surface of small and large intestinal mucosal cells by destroying the microvilli and lying extrcytoplamically beneath the luminal enterocyte membrane
• The intestinal mucosal cells are not destroyed, and the malabsorption and profuse diarrhea characteristic of the disease are produced by destruction of the microvilli

Epidemiology:

• Crytosporidiosis is acquired through ingestion of fecally contaminated material with water being the usual source in epidemics
• It is most commonly seen in immunocompromised individuals particularly those with Aids
• Milder cases of Cryptosporidiosis are also being seen in immunologically competent patients particularly those working on farms and day care centers

General Gross Description:

• Endoscopically the intestinal mucosa is red, non-friable and without ulceration

General Microscopic Description:

• The organisms are seen as spherical 2-5mm basophilic bodies that line up on the surface of intestinal mucosal cells
• No intracellular organisms are seen
• Electron microscopy can demonstrate the trophozoites attached to the mucosal cell surfces as well as oocysts
• While the organisms are easily seen on H&E, silver and Giemsa stains can aid in the diagnosis
• Mild nonspecific inflammation of the lamina propria can been seen in most cases with severe cases showing some acute inflammation
• There is an absence of necrosis or ulceration

Clinical Correlations:

• The symptoms are crampy apin and profuse watery diarrhea which may be accompanied by low grade fever and nausea
• Hyperactive bowel sound may be heard and more severe cases have abdominal tenderness
• In experimental animals the symptoms occur 3-5 days after ingestion of the oocysts
• While examination of stool can reveal the parasites, the most common mode of diagnosis is mucosal biopsy of the colon
• The disease can be self limited in patients competent to produce anti-parasite IGA, but in immunocompromised patients it can remain a difficult to treat chronic illness

References:
•Sleisenger MH and Fordtran JS, Gastointestinal Diseases WB Saunders Philadelphia 1993 pp1203-1204