Background & Objectives: Cryptosporidium is a coccidial protozoa parasite belonging to subphylum of Apicomplexa. Although it is globally widespread and its species exist all over the world, this parasite was unknown until several years ago. Nowadays it is considered as an important infective agent in Immunocompromised hosts especially patients with AIDS. Due to high mortality rate of this infection in immunocompromised and cancerous patients and because of the popularity of Urmia as one of the animal husbandry regions in Iran and since this disease is likely to transfer from animals to human beings this study was conducted to determine the rate of contamination with this parasite.

 Methods: This case-control study was performed on 72 children (case) with cancer who referred to oncology clinic of Urmia Imam Hospital during 2001. Another 30 children with normal immune system were selected as controls. To determine the amount of contamination with parasite, two fecal specimens were collected from each patient. After being concentrated with Formalin–Ether, these specimens were examined using modified acid fast method.

 Results: Three cases of�cryptosporidiosis was seen in the patients (4.16%). Of these, there were 2 patients from the rural area and 1 from urban region. There was no significant relationship between the presence of cryptosporidiosis and living in rural or urban areas.

 Conclusion: Cryptosporidium was detected in three cases of the patients under study who were undertaking chemotherapy. However since the population under study was small, no statistically significant relationship was found between being immunocompromised and contamination with parasite.

 Background & Objectives: Cryptosporidium is an intracellular – extracytoplasmic parasite that has taken much attention in last 20 years as a clinically important human pathogen. Cryptosporidial infection can be transmitted from fecally contaminated food or water and from animal-human or human-human contact. In immunocompromised persons, the illness is much more severe such as debilitation, fatigue, cholera-like diarrhea, severe abdominal cramps, low-grade fever, severe weight loss and Anorexia. Because there was no regional study about cryptosporidiosis in Ardabil, we carried out this survey to determine the prevalence of cryptosporidiosis among the children hospitalized in Ardabil.

 Methods: This descriptive and analytical study was carried out on 371 patients in Sabalab and Aliasghar hospitals of Ardabil between 2004 and 2005. A questionnaire was filled for each patient. Stool samples were examined by concentrated formal - ether method and stained with modified Ziehl-Neelson method. The data were analyzed with SPSS (ver 11) using Chi-square test.

  Results: We analyzed 371 stool samples from children with diarrhea. Cryptosporidium oocysts were detected microscopically in 15 samples. Its prevalence was 4.04% in infected patients. 66.7% of the infected ones were at the age of 6 to 24 months, 20% 25-48 months, and 13.3% 49-72 months.

 Condusion: Because cryptosporidiosis was more prevalent at the age of 6-24 months, health education is more necessary for their mothers.