Intestinal Parasitic Infections among Iraqi Patients: A Multicenter Cross-Sectional Study Integrating Microscopy, Molecular Confirmation, and Risk-Factor Analysis

Abstract

This study was conducted to evaluate the prevalence of intestinal parasitic infections among patients in Iraq and the associated risk factors. Intestinal parasitic infections continue to be a major cause of gastrointestinal morbidities in areas where environmental conditions and personal hygiene favor the transmission of parasites. Most published studies in Iraq are limited mainly to single-center designs and depend on microscopy, which underestimates the true prevalence of infections and cannot differentiate between morphologically similar parasites. This study was designed to provide more accurate estimates of the prevalence of intestinal parasitic infections in Iraq. A cross-sectional study was conducted from January 2025 to March 2026 in six governorates of central and southern Iraq, including Baghdad, Babylon, Karbala, Najaf, Wasit, and Thi-Qar. A total of 240 stool samples were collected, with 40 samples obtained from each governorate. The stool samples were examined by direct saline wet mounts and iodine wet mounts and after concentration by formalin-ethyl acetate. Modified Ziehl-Neelsen staining was also used. Molecular confirmation by PCR included selected protozoan parasites: Entamoeba histolytica, Entamoeba dispar, Giardia duodenalis, Cryptosporidium parvum, and Cryptosporidium hominis. Demographic, clinical, environmental, and behavioral data were analyzed by chi-square testing and multivariable logistic regression. Intestinal parasites were detected in 94 of 240 patients, giving an overall composite prevalence of 39.2%. Parasites were seen in 78 samples by microscopy (32.5%) and in 89 samples by PCR for selected protozoan parasites (37.1%). The highest infection rates were recorded in Wasit and Thi-Qar (45.0% each), and the lowest rate was observed in Karbala (32.5%). The most frequently confirmed parasites were Giardia duodenalis (12.1%), Entamoeba histolytica (10.8%), Entamoeba dispar (7.1%), Cryptosporidium parvum (6.7%), and Cryptosporidium hominis (3.3%). Microscopy and PCR had substantial agreement with a Cohen's kappa coefficient of 0.808. Microscopy had a very high specificity of 96.7% but a sensitivity of 82.0% when compared with PCR. Irregular handwashing after toilet use, untreated drinking water, age below 15 years, and animal contact were identified as independent risk factors for infection by multivariable logistic regression.