Response to Villena et al.: Toxoplasma strain type and human disease

Abstract Recent work has confirmed our earlier assertion that cases of human toxoplasmosis can involve more than one parasite type. This possibility might not have been previously observed because parasite samples studied by earlier workers had been subjected to extended passage through mice. We thus agree with the suggestion that future work examining the relationship between Toxoplasma strain type and human disease should be confined to the analysis of primary clinical material.