Can toxoplasmosis be cured, and is it contagious?

Can toxoplasmosis be cured?

Not at present. The drugs used against Toxoplasma work on the fast-replicating tachyzoite stage, the form responsible for acute illness. They are good at that. What they cannot do is reach the bradyzoites sitting inside tissue cysts in brain and muscle, which are metabolically quiet and walled off behind a cyst wall the drugs do not cross¹. Treatment therefore ends an episode of disease without ending the infection.

This is why a course of treatment does not turn a positive antibody test negative, and why doctors do not re-test to confirm cure. Which drugs are used and who actually needs them is covered on the toxoplasmosis treatment page.

Does toxoplasmosis stay in your body forever?

Yes. Once the cysts form, usually within the first few weeks of infection, they persist for the rest of your life². Antibodies persist too, which is why a positive IgG result stays positive indefinitely and records an old infection rather than a current illness. What that result means is explained on the blood tests page.

Permanent sounds alarming and in this case mostly is not. Your immune system keeps the cysts in check without any help, and roughly a third of the world lives this way without consequence. The lifelong infection matters in two situations: if immunity fails, covered on the weakened immune system page, and in the eye, where old cysts can reactivate locally and cause the recurrent inflammation described on the ocular toxoplasmosis page.

Is toxoplasmosis contagious from person to person?

Not through any ordinary contact. You cannot catch it by touching, kissing, sharing food or utensils, coughing, or living with someone who carries the parasite³. There is no need to isolate anyone or take precautions around an infected person.

There are three genuine routes of human-to-human transmission, and all are unusual. The first is from a mother to her unborn baby during a first infection in pregnancy, which is the one that matters in practice and is covered on the congenital toxoplasmosis page. The second is organ transplantation, where a seropositive donor organ can carry cysts into a seronegative recipient. The third is blood transfusion, which is rare¹. Everyday infection comes from food, water and soil instead, as set out on the meat, water and soil page.

Will there ever be a cure?

Clearing the dormant stage is an open research problem rather than a solved one. The obstacle is biological: the bradyzoite inside a cyst is slow, metabolically quiet and shielded, so the drug targets that work against an actively dividing parasite are mostly absent or inactive. Compounds that kill cysts in culture have repeatedly failed to clear them in animals¹.

Work in this laboratory and others is aimed at the underlying biology: which parasite genes are needed to establish and maintain the cyst, and which host pathways keep it contained. Any real cure would have to come from that, and the same applies to a human vaccine, which does not exist. You can read what we work on under research.

Sources

1. Dunay IR, Gajurel K, Dhakal R, Liesenfeld O, Montoya JG. Treatment of Toxoplasmosis: Historical Perspective, Animal Models, and Current Clinical Practice. Clin Microbiol Rev 2018;31:e00057-17. PubMed · DOI
2. Montoya JG, Liesenfeld O. Toxoplasmosis. Lancet 2004;363:1965-76. PubMed · DOI
3. Centers for Disease Control and Prevention. Toxoplasmosis. Accessed 22 October 2026.