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 (LD90) after 8, 16, & 24hrs
of exposure to doses 100, 50, & 25mg/ml, respectively, while reduction rate of (EC50) after 8,
16, &24 hrs of exposure to dose 50, 25, & 12.5mg/ml, respectively. MVs LD90 efficacy on cysts
was detected after 30 seconds while EC50 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.