Treatment of toxoplasmosis in pregnancy

If infection is acquired before 18 weeks of gestation
And fetal infection is not suspected or diagnosed
Therapeutic abortion is not recommended :
- Early treatment can prevent fetal infection as tachyzoites take 4-8 weeks to cross placenta

If infection is acquired at or after 18 weeks of gestation
And fetal infection is suspected or diagnosed by amniocentesis
Mechanism of action
Inhibition dihydrofolate reductase
Inhibition synthesis of DNA and RNA
Adverse effects :
Category C drugs : cause teratogenic effects in the first trimester .
- Bone marrow suppression
Folic acid antagonist .
Precautions
Not used in the first trimester
Regular CBC
Leucovorin Ca supplement .

Notes
If there is allergy to sulfa , sulfadiazine can be replaced by clindamycin.
Another alternative to the standard triple scheme is :
trimethoprim + sulfamethoxazole
All drugs should be continued until delivery
All drugs active only against tachyzoites