Preventing laboratory-acquired Toxoplasma gondii infection: literature review and case-based post-exposure prophylaxis proposal

Occupationally acquired cases of the intracellular parasite Toxoplasma gondii have been reported, even though there is uncertainty on which infection prevention measures should be implemented in such event. We report a clinical case of laboratory-acquired toxoplasmosis and propose a protocol for post-exposure prophylaxis, given there are no formal guidelines. In this community case study, we describe the management and prevention protocol following an occupational laboratory exposure by a healthy 30-year-old Toxoplasma -seronegative female researcher who suffered an accidental needle puncture with a sample containing a genetically modified hypervirulent Toxoplasma gondii strain. Post-exposure prophylaxis (PEP) with trimethoprim-sulfamethoxazole was implemented for 4 weeks, during which seroconversion occurred, without any accompanying symptoms. Toxoplasma IgM and IgG positivity was observed 21 and 50 days after exposure, respectively, using a validated commercial electrochemiluminescence immunoassay (ECLIA, Roche). Follow-up was maintained for 1 year, during which the patient remained asymptomatic. This report highlights the importance of special care, surveillance and decision on the need for PEP upon occupational laboratory accidental exposure to Toxoplasma gondii . Since there are no guidelines on what the optimal PEP regimen should be, after a literature review, we propose a PEP occupational safety protocol to be implemented in laboratories that handle samples containing Toxoplasma gondii , either in clinical or research setting.