Toxoplasmosis

Background

• Most common cause of focal encephalitis in patients with AIDS

Clinical Features

• Headache
• Fever
• Focal neurologic deficits
• AMS
• Seizures

Differential Diagnosis

• Lymphoma
  • More commonly single lesion in the periventricular white matter or corpus callosum
• Cerebral TB
  • Characteristic inflammatory appearance with isodense exudate filling basal cisterns
• Fungal infection

Diagnosis

• Head CT without contrast
  • Shows multiple subcortical lesions w/ predilection for basal ganglia
  • Contrast usually not needed; if obtained, will show ring enhancing lesions
• CSF
  • Helpful but high rate of false negatives

Treatment

Antibiotics

Immunocompetent

Antibiotics only needed if patient has severe symptoms

• Pyrimethamine 200mg PO one dose (for loading) THEN 50mg PO q24hrs x4wks AND
  • Leucovorin 10mg PO q24hrs AND
  • Sulfadiazine 1g PO q6hrs

Immunosprepressed

• TMP/SMX 5mg/kg IV q12hrs OR
• Pyrimethamine 200mg PO one dose (for loading) THEN 75mg PO q24hrs x4-8wks AND Leucovorin 25mg PO q24hrs PLUS
  • Sulfadiazine 1500mg PO q6hrs OR
  • Clindamycin 600mg PO or IV q6hrs OR
  • Azithromycin 12000mg PO q24hrs OR
  • Atovaquone 1500mg PO q12hrs

Pregnant

• Spiramycin 1 g orally every 8 hours
  • If amniotic fluid is positive treat with 3 weeks of pyrimethamine (50 mg/day orally) + sulfadiazine (3 g/day orally in 2-3 divided doses)
  • Alternate with a 3-week course of Spiramycin 1 g 3 times daily OR
• Pyrimethamine (25 mg/day orally) and sulfadiazine (4 g/day orally) divided 2 or 4 times daily until delivery AND
  • Leucovorin 10-25 mg/day orally to prevent bone marrow suppression

Steroids

• Consider dexamethasone 4mg IV q6hr for significant edema or mass effect

Folinic Acid

Administer if the treatment regimen includes Leucovorin

• Folinic acid 10mg PO QD x6–8wk

Disposition

• Admit