Patients at risk:
(1) HIV-positive patient with AIDS
(2) cardiac transplant recipient
(3) bone marrow transplant recipient
Potential routes of infection:
(1) reactivation of latent infection
(2) primary exposure (cat feces, contaminated food, soil, undercooked meat)
(3) passive transfer from cardiac transplant (seronegative recipient, seropositive donor)
(4) blood transfusion
Clinical findings:
(1) headache
(2) altered mental status
(3) focal neurologic deficits
(4) hemiparesis
(5) ataxia
(6) facial weakness
Imaging findings:
(1) Patients with HIV infection may have one or more mass lesions with a marked ring enhancement.
(2) The degree of ring enhancement in a transplant patient depends on the degree of immunosuppression - it is marked with mild immunosuppression and minimal with severe immunosuppression.
Laboratory testing:
(1) demonstration of tachyzoites on brain biopsy
(2) seroconversion or rise in titers on ELISA testing for antibodies to T. gondii in the presence of ring enhancing lesion on imaging studies
(3) PCR on CSF
