Role of Cryptosporidium spp in Development of Colorectal Cancer

BACKGROUND: Colorectal cancer is one of the most common malignancies in humans. About 20% of the cancer incidence was attributed to infectious agents highlighting the association between infectious agents and the development of cancers. It has been suspected that Cryptosporidium spp. infection may be correlated with colon adenocarcinoma. AIM: investigate the percentage of cryptosporidiosis among colorectal cancer patients. SUBJECTS: 100 patients were recruited from Medical Research Institute, Alexandria University. METHODS: Fresh stool specimens were collected, homogenized and examined using direct wet mount and by permanent staining of faecal smears using Modified ZN staining. Molecular detection by PCR amplification of Cryptosporidium COWP gene. RESULTS: Significantly higher proportion of colorectal cancer patients (32.5%, 42.5%) tested positive by MZN and ELISA respectively compared to only 3.3% and 5% of positive MZN and ELISA among control group. Also, positive PCR was detected among higher proportion of colorectal cancer patients (47.5%) and only 5% of control group. Odds of colorectal cancer is 19 times among positive cases of Cryptosporidium by PCR than those without proven infection by PCR (OR 19.12; 95% CI 4.82-75.99). Comparison of the assessment of Cryptosporidium infection made by two techniques produces a kappa value of 0.770, and .759 respectively between NZN, ELISA and PCR as a gold standard, suggesting a good agreement between the two techniques and PCR. This value of kappa is significantly different from zero, K.770, p<0.001 for MZN and K.759, p<.001 for ELISA. Specificity of MZN (100%) is higher than that of ELISA (96.2%) and both reported higher specificity than sensitivity denoting that both tests are good positive to rule in the presence of infection at 40% prevalence. CONCLUSION: Cryptosporidium infection is significantly higher among cancer colon patients reinforcing that it might be considered as a likely risk factor for the development cancer colon.