Toxoplasma gondii from Gabonese forest, Central Africa: first report of an African wild population

Abstract

The protozoan Toxoplasma gondii is a ubiquitous and highly prevalent parasite that can theoretically infect all warm-blooded vertebrates. In humans, toxoplasmosis causes infections in both immunodeficient and immunocompetent patients, congenital toxoplasmosis, and ocular lesions. These manifestations have different degrees of severity. Clinical severity is determined by multiple factors, including the genotype of the T. gondii strain involved in the infection. T. gondii exhibits remarkable genetic diversity, which varies according to geography and ecotype (domestic or wild). Previous studies have demonstrated that wild strains of T. gondii are of particular epidemiological interest, as they have been associated with more severe forms of toxoplasmosis in different regions of the world. However, no data on wild strains of T. gondii are available from Africa. In this study, we describe for the first time a wild T. gondii population from Africa. Wild animals from the forest environment of Gabon, Central Africa, were screened for chronic infection with T. gondii using quantitative PCR. The infecting T. gondii strains were genotyped whenever possible by the analysis of 15 microsatellite markers and by whole-genome sequencing. A new genotype was identified and was found to be highly divergent from previously described T. gondii populations worldwide, including those from the domestic environment in Gabon. Whole genome-based analyses indicated that this strain was genetically closer to a wild Pan-American population than to domestic African populations. This discovery marks the first description of a wild T. gondii population in Africa. The role of wild T. gondii strains in the incidence of severe toxoplasmosis in Africa remains unclear and requires further investigation. Author SummaryThe emergence of new pathogens from wildlife is today a well-recognized health threat. Studying these infectious agents has proven to be challenging due to the difficulty in accessing to samples from wild animals. In the present study, we took advantage of a recent survey on the viral carriage of wild animals from Gabon, Central Africa, to screen animal samples for the presence of the zoonotic protozoan Toxoplasma gondii, a ubiquitous and highly prevalent parasite that can theoretically infect all warm-blooded vertebrates, including humans. This parasite is the etiological agent of toxoplasmosis, a disease causing a substantial public health burden worldwide through different clinical manifestations and varying degrees of severity. A novel genotype was identified and found to be highly divergent from previously described T. gondii populations worldwide, including those from the domestic environment in Gabon. This discovery marks the first description of a wild T. gondii population in Africa. It has been shown that wild strains of T. gondii are of significant epidemiological relevance, as they have been associated with more severe forms of toxoplasmosis in different regions of the world. The implications of wild T. gondii strains in the incidence of severe toxoplasmosis in Africa remain unclear and merit further investigation.