EPIDEMIOLOGICAL AND MOLECULAR DETECTION OF ENTAMOEBA HISTOLYTICA AND GIARDIA LAMBLIA IN ENVIRONMENTAL AND CLINICAL SAMPLES

Waterborne and soilborne protozoan parasites, most notably Entamoeba histolytica and Giardia lamblia, represent a complex public health challenge in resource-limited settings. This study presents an epidemiological and molecular evaluation of the prevalence of both parasites across diverse environmental matrices (N = 300), including surface water, tap water, and agricultural soil, integrated with a clinical assessment.
Direct light microscopy identified parasitic cysts belonging to the Entamoeba complex in 75 samples (25.0%). However, nested polymerase chain reaction (nested-PCR) assays refined these diagnoses, revealing that only 37 samples (12.3%) harbored the pathogenic E. histolytica, whereas 38 samples (12.7%) contained non-pathogenic species (E. dispar / E. moshkovskii). Regarding G. lamblia, molecular detection yielded a higher positivity rate of 18.7% (n = 56) compared to 15.3% (n = 46) determined microscopically.
Spatial analysis demonstrated significantly elevated contamination levels in peri-urban and agricultural sectors compared to urban centers (p < 0.001), with peak occurrence recorded during the summer season. Genotyping of G. lamblia isolates revealed a predominance of Assemblage B (53.6%), followed by Assemblage A (35.7%). These findings underscore the inherent diagnostic limitations of direct microscopy and advocate for the systematic integration of molecular tools into epidemiological surveillance frameworks and water resource management strategies.