Prevalence and Molecular Detection of Giardia intestinalis in Erbil Province, Iraq: A Cross-Sectional Study

Abstract

Background: Protozoal infections are a major cause of diarrheal disease throughout the world. Giardia intestinalis is one of the most commonly identified intestinal protozoan parasites worldwide . Objectives: This study was carried out to investigate the prevalence rate of Giardia intestinalis among laboratory visitors in Erbil Province and to identify the best and most accurate method for identification. Methods: In a cross-sectional study conducted from June 2024 to March 2025, stool samples were examined from individuals who were referred to Erbil Medical Laboratory Center and some private laboratories for parasitic testing. Real-time Polymerase Chain Reaction (Rt-PCR) was performed for 96 samples, 20 of which had negative microscopy results. The study aimed to investigate epidemiological factors influencing giardiasis and to evaluate the performance of RT-PCR to detect parasites missed by microscopy. Results: Giardia intestinalis was found in (1.48%) 74/5000 of total samples and 74/470 (15.74%) of protozoan infections. The highest infection 32 (6.8%) was detected in the 26–35 year old age group. Gender analysis revealed that 62 (13.19%) were male higher than female. Occupational analysis showed elevated infection rates among food-industry workers 14 (2.98%) and supermarket workers 11 (2.34%) workers. Among infected individuals, the common water sources included mixed tap water, along with intake of raw vegetables. Clinically,45 (9.57%) of infected persons were asymptomatic; symptomatic patients reported mild or intermittent gastrointestinal symptoms. PCR detected 87/96 (90.63%) compared to microscopy 74/96 (77.08%) in the same subset. Real-time PCR demonstrated higher sensitivity (98.65%) compared to microscopy by amplification of the gdh gene, while the sensitivity of microscopy was relatively low (83.91%) with a P value as highly significant (p < 0.00001). Conclusion: Giardia intestinalis prevalence in Erbil is relatively low compared to other Iraqi regions. Surveillance strategies are needed and should be contextualized with molecular diagnostic procedures, taking possible limits on molecular detection into account.