Primary prophylaxis
Start primary prophylaxis for toxoplasmosis when the patient’s CD4 count is less than 100 cells/microlitre and the patient has Toxoplasma gondii IgG antibodies.
The regimens below also provide protection against Pneumocystis jirovecii pneumonia (PJP).
Trimethoprim+sulfamethoxazole is the most effective prophylaxis against T. gondii. The high-strength (160+800 mg) daily regimen is preferred for T. gondii prophylaxis in patients with HIV infection. Use:
1 trimethoprim+sulfamethoxazole 160+800 mg orally, daily; see below for advice on duration of therapy. For dosage adjustment in adults with kidney impairment, see trimethoprim+sulfamethoxazole PJP prophylaxis dosage adjustment toxoplasma gondii encephalitis, prophylaxis (adult with HIV) trimethoprim + sulfamethoxazole
OR
2 trimethoprim+sulfamethoxazole 80+400 mg orally, daily; see below for advice on duration of therapy. For dosage adjustment in adults with kidney impairment, see trimethoprim+sulfamethoxazole PJP prophylaxis dosage adjustment trimethoprim + sulfamethoxazole
OR
2 trimethoprim+sulfamethoxazole 160+800 mg orally, 3 times weekly; see below for advice on duration of therapy1. trimethoprim + sulfamethoxazole For dosage adjustment in adults with kidney impairment, see trimethoprim+sulfamethoxazole PJP prophylaxis dosage adjustment.
Assess patients reporting hypersensitivity to trimethoprim+sulfamethoxazole. Desensitisation (see Principles of antimicrobial desensitisation) is an option for clinically stable patients; however, do not desensitise patients with severe hypersensitivity (eg drug rash with eosinophilia and systemic symptoms [DRESS], Stevens–Johnson syndrome / toxic epidermal necrolysis [SJS/TEN]) or if adherence to therapy is unlikely. If 1 day of therapy is missed, the patient’s hypersensitivity will return and desensitisation must be performed again. Seek expert advice if desensitisation is being considered. If desensitisation is not an option, alternative regimens are provided below.
For patients with nonsevere hypersensitivity to trimethoprim+sulfamethoxazole, use dapsone daily or weekly (in combination with weekly pyrimethamine and calcium folinate). Consider patient preference, adherence and tolerability when choosing between the daily and weekly regimens.
If a daily dapsone-based regimen is preferred, use:
dapsone 50 mg orally, daily; see below for advice on duration of therapy23. For dosage adjustment in adults with kidney impairment, see dapsone dosage adjustment toxoplasma gondii encephalitis, prophylaxis (adult with HIV) dapsone
PLUS
pyrimethamine 50 mg orally, once weekly; see below for advice on duration of therapy toxoplasma gondii encephalitis, prophylaxis (adult with HIV) pyrimethamine
PLUS
calcium folinate 30 mg orally, once weekly (preferably not on the same day pyrimethamine is taken); see below for advice on duration of therapy. toxoplasma gondii encephalitis, prophylaxis (adult with HIV) calcium folinate
If a weekly dapsone-based regimen is preferred, use:
dapsone 200 mg orally, once weekly; see below for advice on duration of therapy23 dapsone . For dosage adjustment in adults with a glomerular filtration rate (GFR) less than 10 mL/min, seek expert advice
PLUS
pyrimethamine 75 mg orally, once weekly (on the same day dapsone is taken); see below for advice on duration of therapy pyrimethamine
PLUS
calcium folinate 30 mg orally, once weekly (preferably not on the day dapsone and pyrimethamine are taken); see below for advice on duration of therapy. calcium folinate
For patients with severe hypersensitivity to trimethoprim+sulfamethoxazole (eg anaphylaxis, DRESS, SJS/TEN), choosing a safe and effective regimen is complex—seek expert advice. Do not give dapsone because there is a possibility of cross-reactivity between dapsone and sulfamethoxazole (see Cross-reactivity between sulfonamides).
Duration of therapy: for patients taking combination antiretroviral therapy with a suppressed HIV viral load, stop primary prophylaxis when the CD4 count is more than 200 cells/microlitre for 3 months.