CM phenotype describes mice that were judged as developing CM if they displayed neurological symptoms including mono-, hemi-, para-, or tetraplegia, movement disorder, ataxia, hunching, convulsions, and coma, and succumbed to infection by day 12 after inoculation (references 6, 7). Susceptible strains developed neurological symptoms within 6–10 d after inoculation. Highly susceptible mice showed both a significantly higher parasite density and an early onset of neurological symptoms and death than susceptible mouse strains. Resistant strains displayed a significantly delayed onset of neurological symptoms and improved survival compared with susceptible groups. Highly resistant strains did not develop neurological symptoms and displayed enhanced survival compared with resistant strains. Strains analyzed in this study are bolded. Other strains (italicized) were derived as previously described (references 26–28).