The majority of Toxoplasma gondii strains from a variety of human and animal sources have
been grouped into three highly clonal but closely related lineages. The low occurrence of
nucleotide differences among the three predominant lineages and their unusual dimorphic
allelic composition suggest that they have arisen from a recent common ancestry. Less than
1% of the previously studied strains contain unique genotypes and high divergence of DNA
sequence, and therefore are considered 'exotic'or 'atypical'strains. The seemingly low …