Prevalence of Blastocystis hominis, Cryptosporidium, and Strongyloidesstercoralis among patients with colorectal carcinoma in Egypt.

BACKGROUND AND AIM: Colorectal cancer (CRC) is a leading cause of cancer-related death, with strong environmental associations and genetic risk factors. Although some microorganisms have been linked to carcinogenesis in CRC, the prevalence of parasites and their potential role in carcinogenesis remain unclear. This study aimed to determine the prevalence and association of the parasites Blastocystis, Cryptosporidium, and Strongyloides in CRC.

PATIENTS AND

METHODS

A case-control study was conducted, including 120 participants, divided into 60 patients with CRC and 60 healthy controls. Patients were recruited from two tertiary care hospitals in Cairo, Egypt. Parasitologic microscopy-based tests for Blastocystis hominis (B. hominis), Cryptosporidium oocysts, and Strongyloides stercoralis (S. stercoralis) rhabditiform larvae were performed using iodine-stained smears after formol ether concentration, modified Ziehl-Neelsen (MZN) staining, and agar plate culture, respectively.

RESULTS

Blastocystis and Cryptosporidium were detected at comparable rates in the CRC and control groups (26.7 % vs 28.3 %, p = 0.83 and 8.3 % vs 10 %, p = 0.75, respectively), with no significant association with CRC in terms of site, pattern, histological types, or stages (p = 0.92, 0.88, 0.84, and 0.39, respectively). However, most cases of Blastocystis or Cryptosporidium were observed in localized CRC in the rectum of the adenocarcinoma type. S. stercoralis was not detected in the stool examinations of either patients or controls.

CONCLUSION

None of the parasites studied demonstrated a significant association with CRC when using conventional microscopy-based methods of parasite detection.