Toxoplasmosis in pregnancy

Management

IgG	IgM	Interpretation	Management
–	–	no prior infection; at risk	counsel on prevention of primary infection (handwashing after litter, cook meat well, no raw eggs or unpasteurized dairy
–	+	acute primary infection or false positive	repeat serology in 2 to 3 weeks; if unchanged, then was false positive
+	–	prior infection	no risk of transmission except rare cases of immunocompromise
+	+	recent or prior infection	do avidity testing: if high avidity, infection was >4 months ago so unlikely to be acute; if low avidity, uncertain

Acute Infection

• If acute infection, such as IgM + / IgG – that converts to IgG +, or IgM + / low IgG avidity with compatible clinical picture
  • Amniocentesis after week 18
    • If PCR positive, treat with pyrimethamine and sulfadiazine plus folinic acid, until delivery
    • If PCR negative, continue prophylaxis with spiramycin 1 g po TID
• Choice of antiparasitic
  • Spiramycin does not cross the placenta, while pyrimethamine and sulfadiazine do
  • However, pyrimethamine is teratogenic before 14 weeks gestation