Comparison of gdh polymerase chain reaction-restriction fragment length polymorphism and tpi assemblage-specific primers for characterization of Giardia intestinalis in children.

Background: Giardia is a diarrheagenic eukaryotic parasite that consists of at least eight morphologically identical but genetically distinct genotypes. Human giardiasis is caused mainly by A and B assemblages. Aim and objectives: The study aimed to compare the performance of gdh polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and tpi assemblage-specific primers in genotyping of G. intestinalis. Materials and Methods: Stool samples of 315 children were microscopically screened for G. intestinalis. Positive samples were genotyped using tpi assemblage-specific primers and gdh semi-nested PCR-RFLP techniques. Results: The prevalence of Giardia was 18.1%. The detected genotypes using tpi and gdh approaches were assemblage A (15.8% vs. 12.7%) and assemblage B (36.8% vs. 74.5%) as single infections and mixed assemblages A and B (47.4% vs. 12.7%). The two approaches showed a moderate agreement (kappa index = 0.413, P < 0.001). PCR-RFLP of gdh gene revealed that sub-assemblages BIII and BIV were equally detected (30.9% each). The remaining samples were equally divided between sub-assemblage AII, mixed BIII and BIV, and mixed AII and BIII (12.7% each). A significant association was detected between the retrieved sub-assemblages and the presence of symptoms. Conclusions: Although both approaches confirmed the predominance of assemblage B, the use of assemblage-specific primers is more effective in elucidating the true picture of mixed assemblage infection.

Detection of Giardia intestinalis assemblages A and B among children from three villages in the West Delta region, Egypt using assemblage specific primers.

Giardia intestinalis is a common diarrheagenic parasite infecting children globally. It has been classified into eight morphologically identical but genetically distinct genotypes. Human infection is mainly associated with A and B assemblages with variable geographical distribution. The present work aimed to study the epidemiology of assemblages A and B in children inhabiting different areas in Lower Egypt. Stool samples were collected from 315 children and examined microscopically for parasitic infections. Giardia positive samples were genotyped using tpi assemblage specific primers. The prevalence of Giardia was 18.1% among the examined children. Mixed assemblages A and B was more common (47.4%) than single assemblage B (36.8%) or A (15.8%). The distribution of different genotypes was significantly associated with the residence area, animal contact, and handwashing habits. A non-significant association was observed between Giardia assemblages and the clinical manifestations. Assemblage B is the predominant genotype among Egyptian children. The distribution of different Giardia assemblages is strongly associated with the studied area and the habits of its people.