Toxoplasmosis: A Widespread Zoonosis Diversely Affecting Humans and Animals
Résumé
Infections by the protozoan parasite Toxoplasma gondii are widely prevalent in humans and animals worldwide. Since the discovery of the life cycle of the parasite (1969), several studies identified sources of contamination for humans through ingestion of viable tissue cysts in raw or undercooked meat or ingestion of food and water contaminated with sporulated oocysts after shedding in the feces of infected felids. Prevalence of toxoplasmosis varies between different countries and regions in the same country depending on age, social culture, eating habits, and environmental factors. In immunocompetent patients, toxoplasmosis is generally asymptomatic or benign, but severe infections are described in tropical areas due to atypical strains. In immunocompromised patients, T. gondii is an opportunistic parasite that may induce life-threatening disease; severe disease could occur in HIV-infected patients or in transplant patients. Finally, in case of congenital toxoplasmosis, infection can lead to abortion, cerebral damage, or ocular lesions. New genotyping tools were recently applied to field studies in different continents and revealed a complex population structure for T. gondii with a greater genetic diversity than expected, and a relation between genotype of Toxoplasma strain and severity of infection is described. According to different routes of transmission, hygienic measures can be recommended to avoid Toxoplasma contamination. These measures can be completed by a serological screening of patient at risk for toxoplasmosis as it is recommended in France. Although the cost of screening is expensive, the important preventive role of healthcare policies in the decrease of the burden of toxoplasmosis cannot be denied.