Severe T cell defects - Patients are at increased risk for developing Toxoplasma infections. Examples of severe T cell defects include SCID, complete DiGeorge, and MHC class I and II deficiency. Patients with secondary T cell immunodeficiency from HIV infection also have increased susceptibility to Toxoplasmosis infection (mainly encephalitis) which usually manifests when the CD4 T cell count is below 100cells/mm3.
XL hyper IgM (CD40L deficiency) - Patients with CNS toxoplasmosis have been reported. have been reported. The CD40-CD40L interaction appears to be important for immunity against this parasite.