Pulsed Electric Fields as an Effective Tool for Toxoplasma gondii Inactivation

Toxoplasma gondii is an intracellular protozoan transmitted via environmentally resistant oocysts present in food and water, as well as through the consumption of meat containing infective bradyzoites. This study evaluated the inactivation of T. gondii oocysts and bradyzoites (ME-49 strain) by Pulsed Electric Field technology (PEF). Treatment efficacy was determined by mouse bioassay combining brain qPCR and indirect immunofluorescence (IFA), with complementary qPCR in Hs27 cells. The infectious dose (ID₅₀) of T. gondii was estimated at 34.6 oocysts. PEF-treated oocysts (15 kV/cm; 50 kJ/kg; 225 µs) showed a significant reduction in infectivity compared with untreated controls; accordingly, the dose required to establish infection increased to 85.3 oocysts after PEF treatment. Brain qPCR and IFA were highly correlated, whereas heart tissue was less sensitive. Bradyzoites recovered from PEF-treated meat (3.3 kV/cm; 27 kJ/kg; 1600 µs) showed a 50% infectivity reduction compared with untreated samples. In vitro assays confirmed an in vivo reduction in infectivity, indicating that cell cultures can serve as an ethical and efficient tool for preliminary viability assessment. This is the first evidence of T. gondii inactivation by PEF, highlighting its potential as a non-thermal strategy. Further studies are needed to optimize treatment parameters.