Geographical difference of the virulence of Toxoplasma gondii

The genotype of Toxoplasma gondii ( T. gondii ) is expected to be disparate due to its biological and epidemiological diversity; however, these disparities can only be found in Central and South America. Here we attempt to offer an explanation for this contradiction from the perspective of virulence evolution. We provide an evolutionary dynamic framework with the only assumption that the direction of virulence evolution is to maximize its ability to infect more hosts. We made thorough investigations on the experimental and epidemiological survey data of T. gondii to obtain an evaluation of the ranges of transmission related parameters and therefore can capture the global evolutionary scenarios of T. gondii virulence. Our work reveals that transmission route is the key to the geographical difference of T. gondii around the world and the diversity of hosts cannot always increase the diversity of T. gondii virulence. The reproduction mode of T. gondii and frequent human trades are the prerequisites for T. gondii virulence to reach the present status. Our results demonstrate that virulence evolution of T. gondii is a perfect example of evolutionary adaptation to environment, which is also the reason of the successfulness of that parasite. (c) 2023 Published by Elsevier Inc.