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Distinct sequences of Giardia duodenalis assemblages raised the hypothesis that certain assemblages may contribute to its clinical outcome. However, sequences analysis is time consuming, expensive, and needs many manual operations. Nested PCR targeting intergenic spacer (IGS) region was applied successfully to genotype G. duodenalis. This study aimed to identify the prevalence of G. duodenalis assemblages among giardiasis school children and its relation to the presence of symptoms using nested IGS/PCR. Of 65 microscopically confirmed Giardia-positive samples, 65 samples were genotyped proving high sensitivity (92.3%) of IGS/PCR. Negative IGS/PCR samples were also negative for β-giardin gene. Subassemblage AI was the commonest with 66.6% (20/30) among asymptomatic children compared to 53.3% (16/30) of symptomatic, while assemblage B was found in 40% (12/30) of symptomatic compared to 20% (6/30) of asymptomatic. The difference was significant. AII was only found in asymptomatic with 13.4% (4/30), while mixed infections (AI&B) were recorded only in 6.6% (2/30) of symptomatic group. A significant relation was found between younger children susceptibility for AI and B infections as presented in 77.7 (12/16) and 83.3% (10/12) of symptomatic, respectively, and 80 (16/80) and 33.4% (2/4) of asymptomatic, respectively. Significant relations were found between AI with intermittent diarrhea and B with chronic. A significant relation was found between assemblage distributions and heavy infection intensity. In conclusion, higher incidence of assemblage B among symptomatic children compared to asymptomatic could denote its possible pathogenic potential.

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The efficiency of the transmission of Giardia lamblia is assured by the presence of a cyst wall, which provides resistance to drastic osmotic and pH variations. Both magnesium oxide (MgO) nanoparticles (NPs) and microwaves (MVs) are known to inactivate many microorganisms.This study compared the effects of MgO NPs & MVs irradiation on Giardia lamblia cysts in experimental mice as to treated and un-treated cysts viability, excystation, ultrastructure changes and infectivity.The results showed that the G. lamblia cysts count were reduced to (LD 90 ) after 8, 16, & 24hrs of exposure to doses 100, 50, & 25mg/ml, respectively, while reduction rate of (EC 50 ) after 8, 16, &24 hrs of exposure to dose 50, 25, & 12.5mg/ml, respectively. MVs LD 90 efficacy on cysts was detected after 30 seconds while EC 50 after 20 seconds. Failure of excystation was 90% and 98% among MgO NPs and MVs treated cysts. MgO NPs treated cysts showed multiple cytoplasmic vesicular vacuoles while the cyst wall appeared destructive with the release of the cytoplasm outside. MVs treated cysts were filled with one big vesicular vacuole with an increase in size while some contents were decreased in size and others disappeared completely. The infectivity rate among mice inoculated with MgO NPs and microwave treated cysts was 33.3% & 8.2 % with a mild histopathological changes, with significant differences.