Prevalence and associated risk factors of Cystoisospora belli and Cyclospora cayetanensis infection among Iranian patients with colorectal cancer.

From among intestinal parasites, coccidian intestinal parasites such as Cystoisospora belli (previously known as Isospora belli), and Cyclospora cayetanensis are well-known as opportunist parasites, particularly in patients with cancer. This study assessed the prevalence of C. belli and C. cayetanensis in patients with cancer in Lorestan Province, Southwest of Iran. This cross-sectional descriptive study was conducted on 87 patients with colorectal cancers, referred to the general hospitals of Lorestan from October 2017 to August 2018. A fresh stool specimen was collected from each subject in a sterile labeled container. The collected stool samples were concentrated through sucrose flotation method and then prepared for Ziehl-Neelsen staining for microscopic examination. Demographic and possible risk factors such as age, sex, education, residence, and unwashed vegetable/fruit consumption were collected by an applied questionnaire. Out of the 87 patients with colorectal cancer, eight (9.2%) were found positive for C. belli and C. cayetanensis infections, with five (5.74%) and three (3.44%) patients positive for C. belli and C. cayetanensis infections, respectively. Results also showed that sex and unwashed vegetable/fruit consumption were significantly associated with the prevalence of these parasites (p < 0.01). The findings revealed the considerable prevalence of C. belli and C. cayetanensis in patients with colorectal cancers. It is therefore essential for gastrointestinal specialists to pay special attention to the prevalence of coccidian parasites in patients with colorectal cancer.