Canterbury DHB

Toxoplasmosis - Treatment

Toxoplasmosis can complicate prolonged and intensive anti-leukaemic chemotherapy of any type but is most likely to occur post-BMT. It is caused by toxoplasma gondii. Toxoplasmosis in BMT recipients occurs as a result of reactivation of latent cysts in seropositive patients following allogeneic transplantation. It usually occurs in the first six months post-BMT. Patients who develop chronic GvHD remain immunocompromised and are at increased risk for toxoplasmosis. See UpToDate website for general information about toxoplasma.

Clinical Features

Toxoplasmosis is a mild condition in patients with normal immune systems. By contrast, toxoplasmosis in the immunosuppressed patient is often life-threatening. In this situation, pneumonia, encephalitis, myocarditis, or fever without obvious cause may occur. There are no specific findings but the patient may have neurological symptoms or the picture may resemble miliary TB or pneumocystis infection.

Diagnosis

• Serology for IgM toxoplasma titres, although in patients who cannot produce antibodies (such as allogeneic transplant patients) this may be of limited value.
• MRI if CNS disease is suspected.
• PCR for toxoplasma antigen blood or CSF.

Treatment

Note: It is important to start treatment early.

• Pyrimethamine loading dose of 200 mg for one day (regardless of patient weight) followed by, if patient weight:
  • < 60 kg, 50 mg/day PO.
  • > 60 kg, 75 mg/day PO.
• Folinic acid 15 mg once daily PO/IV/IM. Consider a higher dose – 15 to 30 mg four times a day PO if leucopenia develops. Check CBC + diff weekly.
• Sulphadiazine, if patient weight:
  • < 60 kg, 1 g six-hourly PO.
  • > 60 kg, 1.5 g six-hourly PO.
• Clindamycin 600 mg six-hourly IV or PO may be substituted if allergic to sulphadiazine.
• Regime to continue for a minimum of four weeks. Discuss with ID team.

For more information on Pyrimethamine, sulphadiazine, and clindamycin, contact the Haematology pharmacist.

Topic Code: 5024