Genetic diversity of Toxoplasma gondii in South America: occurrence, immunity, and fate of infection

Abstract

Toxoplasma gondii is an intracellular parasite with a worldwide distribution. Toxoplasma gondii infections are of great concern for public health, and their impact is usually most severe in pregnant women and their foetuses, and in immunocompromised individuals. Displaying considerable genetic diversity, T. gondii strains differ widely according to geographical location, with archetypal strains predominantly found in the Northern Hemisphere and non-archetypal (atypical) strains, with highly diverse genotypes, found mainly in South America. In this review, we present an overview of the identification and distribution of non-archetypal strains of T. gondii. Special attention is paid to the strains that have been isolated in Brazil, their interaction with the host immunological response, and their impact on disease outcomes. The genetic differences among the strains are pivotal to the distinct immunological responses that they elicit. These differences arise from polymorphisms of key proteins released by the parasite, which represent important virulence factors. Infection with divergent non-archetypal strains can lead to unusual manifestations of the disease, even in immunocompetent individuals. Graphical Abstract

Comparison of immunological and molecular methods for laboratory diagnosis of ocular toxoplasmosis in blood, serum and tears in Brazil

“…The rates of infection caused by this protozoan are oftentimes higher in tropical environments due to their high humidity and temperatures, which favor oocysts’ sporulation in the soil [ 2 ]. Its prevalence ranges from 25% to 30%, depending on country of occurrence; these rates’ range can reach from 10% to 90% [ 3 , 4 ]. This parasite’s seroprevalence in humans, in Brazil, ranges from 21.5% to 97.4% [ 5 ].…”