Molecular detection and genotyping of Giardia lamblia in diarrheal patients: Analysis of assemblage distribution and risk factors.

Background: Giardia lamblia (G. lamblia) is a common enteric parasite linked to gastrointestinal illnesses, particularly diarrhea, with its prevalence influenced by various factors. Aims and Objectives: This study aimed to detect and genotype G. lamblia in diarrheal patients using real-time PCR with assemblage-specific primers, and to assess associations with potential risk factors. Materials and Methods: A total of 332 stool samples were collected and examined microscopically. Genotyping was performed on positive samples using real-time PCR targeting the tpi and gdh genes. Results: G. lamblia was detected in 50 samples (15%), with single and mixed infections each accounting for 7.5%. The tpi gene was successfully amplified in all microscopically positive samples, revealing that mixed assemblages A&B (46%) were the most common, followed by assemblage B (32%) and assemblage A (22%). The gdh gene was amplified in 96% of samples, showing a similar pattern: mixed assemblages (42%), assemblage B (36%), and assemblage A (18%). Additionally, dual peaks in the gdh gene suggest genetic variability that may assist in subtyping. Assemblage distribution based on the tpi gene was significantly associated with age, residence, and animal contact but not with gender, water source, or clinical symptoms. Conclusion: Real-time PCR effectively detected and genotyped G. lamblia, with a high prevalence of mixed assemblages A&B. The observed genetic variability highlights the importance of molecular tools in understanding Giardia transmission dynamics and supporting targeted public health interventions.