Treatment of toxoplasmosis: drugs, antibiotics

Treatment of toxoplasmosis is only effective in active stages (trophozoites). It does not work on cysts in the central nervous system. It probably does not work on cysts in other tissues either.

Treatment is indicated in the following cases:

• clinically acute toxoplasmosis
• diagnosed primary infection in pregnancy
• proven congenital toxoplasmosis
• disease in immunodeficient patients with overt symptoms

What drugs are used in the treatment of toxoplasmosis?

1. Spiramycin

Spiramycin belongs to the group of macrolide antibiotics. Its action lies in its ability to block the production of bacterial proteins.

2. Pyrimethamine

Pyrimethamine is an antagonist of folic acid metabolism. In practice, it is mainly used in combination with sulfadiazine. This combination reduces the amount of the active form of folic acid (tetrahydrofolate). This is important for the synthesis of nucleotides that are essential for DNA synthesis and for parasite reproduction.

3. Sulfonamides (sulfadiazine)

Sulfonamides are competitive antagonists of paraaminobenzoic acid. Bacteria depend on an external supply of this acid. Paraaminobenzoic acid is essential for folic acid synthesis. Folic acid is essential for their growth. Simply put, they block folic acid synthesis.

The treatment of congenital toxoplasmosis

Treatment of congenital toxoplasmosis is used in the case of:

1. congenital toxoplasmosis that is newly diagnosed in a newborn
2. a newborn who has been prenatally diagnosed with toxoplasma infection

Treatment of congenital toxoplasmosis should be started as soon as possible. A combination of sulfadiazine and pyrimethamine is used for treatment. The duration of treatment is one month. After that, children are given spiramycin for 6 weeks.

What is the dosage of the above medicines?

• Pyrimethamine in children up to 9 months of age - 6.25 mg/day,
• pyrimethamine for children from 10 months of age - 1 mg/kg/day (max 25 mg)
• sulphadiazine for children up to 9 months of age - 100 mg/kg/day (max. 750 mg for children up to 3 months of age and max. 1 000 mg for children up to 9 months of age)
• sulphadiazine from 10 months of age 150 mg/kg/day (max. 1 500 mg)
• spiramycin 100 mg/kg/day in 2 to 4 doses

What is the treatment for pregnant women?

Treatment of pregnant women is problematic. Spiramycin is used in the 1st trimester at a dose of 4 x 0.5 g/day. From the 2nd trimester onwards, a combination of pyrimethamine and sulfadiazine is recommended. Also only if there is evidence of infection in the baby. The treatment cycle lasts 4 weeks.

In the case of treatment with spiramycin alone, the risk of transmission to the baby is reduced by 60%. Treatment with a combination of pyrimethamine and sulfadiazine reduces this risk by up to 90%.

Treatment of ocular toxoplasmosis

Pyrimethamine is administered to patients on the first day at a dose of 75-100 mg. Thereafter at a dose of 25-50 mg once daily. Sulfadiazine is administered at the same time at a dose of 0.5-1 g every 6 hours.

An alternative to the first option is a combination of pyrimethamine + clindamycin (300-900 mg every 6-8 hours). In the ocular form, the corticosteroid prednisone is also given at a dose of 0.5-1.0 mg/kg/day.