| Abstract|| |
A 35-year-old male, positive for Human Immunodeficiency Virus (HIV) antibodies, was found to have heavy infestation by Isospora belli, leading to gastrointestinal opportunistic infection. Stool sample of the patient presenting with diarrhea of 2 months duration showed numerous oocysts of I. belli. His blood CD4 count was 85/cmm. The patient was from a slum area with poor sanitation. He was put on antimicrobial agent trimethoprim-sulfmethoxazole and was followed up. However, he died after 1 month of treatment.
Keywords: Acquired Immunodeficiency Syndrome, isosporiasis
|How to cite this article:|
Mudholkar VG, Namey RD. Heavy infestation of Isospora belli causing severe watery diarrhea. Indian J Pathol Microbiol 2010;53:824-5
| Introduction|| |
Isospora belli is a rare gastrointestinal pathogen in Human Immunodeficiency Virus (HIV) infected patients in North America, whereas it is endemic in some developing countries such as Haiti. 
Cryptosporidium, Isospora, Cyclospora and Microsporidia are increasingly becoming prevalent in Acquired Immunodeficiency Syndrome (AIDS) patients.  Isosporiasis is a chronic diarrheal illness in AIDS patients, caused by the protozoan Isospora belli. The parasitic infection has been commonly reported from different centers of India.  Here, we are reporting a patient with AIDS, having severe watery diarrhea harboring heavily parasitized I. belli oocysts in stool [Figure 1].
|Figure 1: Microscopic photograph showing acid fast I. belli oocysts in stool smear (×400)|
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| Case Report|| |
A 35-year-old male patient, positive for HIV antibodies and residing in a slum area, presented with episodes of diarrhea since 2 months, and fever and vomiting since 8 days. He also had history of weight loss. The patient was moderately dehydrated and cachexic. He had episodes of watery diarrhea with blood and mucus. The stool sample received was examined for saline mount, iodine mount and modified Zeihl-Neilson (Z-N) stain. The reports of routine biochemical investigations were within normal limits. The peripheral smear showed leukopenia with TLC 2700/cmm. The CD4 count was 85/cmm. The wet mount of stool revealed numerous cysts of I. belli measuring about 10 × 20 μm in size, with round granular center. Some of the cysts contained two sporocysts. Stool smear stained by modified Z-N stain showed many acid fast (pink) oocysts [Figure 2]. The patient was put on antimicrobial agent trimethoprim-sulfmethoxazole and was followed up. However, he died after 1 month.
|Figure 2: Microscopic photograph of stool smear stained with modified Z-N stain, showing oocysts of I. belli of size 10 × 20 μm, containing one immature sporont (×1000)|
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| Discussion|| |
I. belli, a relative of Toxoplasma, Cryptosporidium and Sarcocystis species, is a protozoan parasite of the phylum apicomplexa, class sporozoea, subclass coccidian and family eimeriidae. 
The diagnosis of isosporiasis is made following detection of oocysts (10 × 20 μm) of I. belli, which are passed in stool. Usually, the oocyst contains only one immature sporont but two may also be present. Continued development occurs outside the body with the development of two mature sporocysts, each containing four sporozoites. The sporulated oocyst is the infective stage, which upon ingestion, excyst in the small intestine releasing the sporozoites that penetrate the mucosal cells and initiate the life cycle in the infected host. Intestinal infection due to I. belli is distributed worldwide and the highest incidence has been reported from underdeveloped countries. The prevalence of I. belli infection was estimated to be 15% of AIDS patients in Haiti, but is <0.2% in US AIDS population. ,
In India,  the prevalence of I. belli infection is about 12% in AIDS patients. Very rarely, disseminated extraintestinal infection may occur.  Kumar et al. have found the incidence of I. belli infection 18.6% of chronic diarrhea and 7.3% of acute diarrhea in HIV positive patients. Lanjewar et al., in their study of 77 cases of HIV patients, found four cases of isolated isosporiasis. 
Diarrhea is often the presenting symptom of full blown AIDS and is characterized by large volume, presence of blood and abdominal pain, as seen in this patient.
Isosporiasis of the gastrointestinal tract responds readily to therapy with trimethoprim-sulfmethoxazole. I. belli should be considered a part of spectrum of potentially treatable infectious agents in patients with AIDS. It is therefore recommended that for patients of AIDS with diarrhea, an apprehensive examination for pathogenic bacteria, protozoa helminthes, etc. should be done.
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Vishal G Mudholkar
C/o Dr. Ravindra D. Namey, "Swarnim" A-18, Arihant Park, Behind SSC Board, Kolhapur - 416 004, Maharashtra
[Figure 1], [Figure 2]