Antiprotozoal activity of magnesium oxide (MgO) nanoparticles against Cyclospora cayetanensis oocysts

Outbreaks of Cyclospora cayetanensis infection have been linked to consumption of food and water contaminated by oocysts that can survive both physical and chemical disinfectants. Magnesium oxide (MgO) nanoparticles (NPs) can be potentially used in food as bactericides. In this study, C. cayetanensis pre- and post-sporulated oocysts were exposed to MgO NPs with different doses ranging from 1.25-25 mg/ml. With comparison to control, the antiprotozoal activity of MgO NPs was evaluated by identifying the median effective concentration dose (EC₅₀), lethal concentration dose (LC₉₀), microscopically changes on treated oocysts and rates of sporulation. Among pre- and post-sporulated oocysts, MgO NPs ≥ EC₅₀ was observed after 24 h at concentrations 10 and 12.5 mg/ml, respectively, while ≥ LC₉₀ was observed after 24 h, 48 h and 72 h at concentrations 15, 12.5 and 10 mg/ml, respectively. MgO NPs treated oocysts showed abnormal morphological changes such as an increase in size, wall injury, deposition of vacuolated homogenous particles in the cytoplasm, evacuation of oocyst's contents, and collapse. Sporocysts of treated oocysts were noticed to be peripherally shifted. Sporulation failure of treated oocysts achieved ≥90% after 24 h and 72 h of incubation with 15 and 12.5 mg/ml, respectively, while it was 10.1% among non-treated. All the differences were statistically significant. Our results demonstrated that MgO NPs has a significant anti-Cyclospora effect on both unsporulated and sporulated oocysts, especially considering that it could be biologically synthesized, that way it can be used safely as a preventive agent in food and water disinfectant treatment.