Microsporidiosis differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ogheneochuko Ajari, MB.BS, MS [2] Ahmed Younes M.B.B.CH [3]

Overview

Microsporidiosis should be differentiated from other conditions that cause chronic diarrhea in immunocompromised patients.

Differentiating Microsporidiosis from other Diseases

Differential Diagnosis

Microsporidiosis must be differentiated from other diseases that may cause chronic diarrhea, weight loss, and abdominal pain especially in immunocompromised patients.

Disease	Prominent clinical findings	Laboratory or radiological findings
Chronic giardiasis	Chronic giardiasis may develop after acute episode of giardiasis or without any acute events. Loose foul smelling stools Flatulence Fatigue Weight loss Steatorrhea Some patients develop acquired lactose intolerance (manifested by exacerbation of symptoms following ingestion of dairy products)	Microscopic identification of the organism in the stool Hypoalbuminaemia Vitamin B12 and folate deficiencies (as the organism inhabits the duodenum)
Cryptosporidiosis	Incubation period is 7-10 days. In immunocompetent patients: Disease might be asymptomatic or cause gastroenteritis (but without any biliary involvement) Gastroenteritis usually resolves spontaneously within 14 days. In immunocompromised patients: Disease is usually more severe and prolonged (especially in severly immunocomprmised patients with CD4 count < 100 cells/microL). Cryptosporidiosis may involve the biliary tract and the liver. Weight loss Abdominal RUQ tenderness might be present if biliary or hepatic involvement is present.	Microscopic identification of the organism in the stool: The oocysts appear red on staining with modified acid fast staining PCR: Most specific and sensitive diagnostic tool. PCR is expensive and used in limited cases.
Cystoisosporiasis (isosporiasis)	Cystoisosporiasis is usually seen in immunocompromised patients. Incubation period can last up to 2 weeks Watery diarrhea that is profuse and foul smelling Constitutional symptoms (headache, low grade fever, myalgia and malaise)	Isospora ova or parasites can be visualized on stool microscopic examination. Upper GI endoscopy may used for excluding other esophageal or gastric disease and obtaining specimens for histopathology.
Tropical sprue	History of travel to a tropical region (for a period more than a month) Chronic diarrhea Steatorrhea Examination may show signs of vitamin deficiencies (eg glossitis)	Megaloblastic anemia that might progress into pancytopenia Hypoalbuminaemia Vitamin D defeciency and hypocalcemia