Protozoa infections - Toxoplasmosis
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Immunocompetent persons with primary infection are usually asymptomatic, but latent infection can persist for the life of the host. In immunosuppressed patients, especially patients with AIDS, the parasite can reactivate and cause disease, usually when the CD4 lymphocyte count falls below 100 cells/mm3.
Clinical presentation
- Altered mental status
- Focal neurological deficits
- Seizures
- Neuropsychiatric manifestations
Imaging Investigations
- Contrast head CT scan - demonstrates ring-enhancing lesions
- Contrast brain MRI with diffusion weighted sequences (DWI)
- CXR
Laboratory Investigations
Toxoplasma serology (IgM)
Non-pharmacological Treatment
Similar to bacterial meningitis
Pharmacological Treatment
For acute infection give:
D:sulfadiazine (PO) 1g 6hourly for 6weeks
AND
D: pyrimethamine (PO) 100mg loading dose then 50mg /day for 6weeks
AND
S: folinic acid (PO) 10mg /day for 6weeks
After six weeks of treatment give maintenance treatment with
D: sulfadiazine (PO) 500mg 6hourly
AND
D: pyrimethamine (PO) 25-50mg /day
AND
S: folinic acid (PO) 10mg /day until CD4 counts is above 200cells/microlitre and/or undetectable viral load for 3-6months
For those allergic to sulphur replace sulfadiazine with
S: clindamycin (PO) 450mg 6hourly for for 6weeks.