For everyone
Toxoplasmosis, answered
About a third of all people carry Toxoplasma gondii, and most will never notice. For some it matters a great deal. These pages explain what is known, what is not, and what is only a scare story.
For information, not diagnosis. This page explains the science. It cannot take your own situation into account, so for decisions about your health or a pregnancy, talk to your doctor.
I have studied this parasite in the laboratory for twenty years. These pages are what I tell friends and family when they ask. Every page says what the evidence is and where it comes from, and carries the date it was last updated, because the science moves.
What toxoplasmosis is, and who needs to care
The parasite, how people catch it, and the three situations in which it is dangerous.
Pregnancy: the real risks and the sensible precautions
Why only a first infection during pregnancy matters, what testing can tell you, and a short list of precautions that work.
Cats: what they do and what they do not do
You almost certainly do not need to give up your cat. Here is why, and what to do about the litter box.
Meat, water, soil and shellfish: infection beyond cats
Most infections never involve touching a cat. Where the parasite really comes from, and how cooking and washing deal with it.
Blood tests explained: IgG, IgM and avidity
What a positive result means, what it cannot tell you, and whether a test can reveal which strain you carry.
Why the same parasite is mild in Europe and severe in South America
Strains differ enormously. This has been the main subject of my own research.
The eye: ocular toxoplasmosis
The most common serious consequence in otherwise healthy people, and one that is often missed.
The brain and behavior: what the evidence shows
Does a parasite change your personality? A careful look at a famous claim.
Treatment, and why there is still no vaccine
What the drugs can and cannot do, and what stands between us and a vaccine for people.
Pets and livestock: toxoplasmosis, Neospora and Sarcocystis
For owners, farmers and veterinarians: the related parasites that cause abortion in cattle and disease in dogs and birds.
What our lab studies
We study the molecular basis of Toxoplasma disease: how the parasite evades immunity, spreads through the body and persists, and which parasite and host genes decide the outcome. Part of that work asks why some strains cause severe eye disease even in people with a healthy immune system.