>Nearly one quarter of Americans have already been infected with the brain parasite toxoplasma. But in healthy, non-pregnant individuals, the parasite just sit

>Nearly one quarter of Americans have already been infected with the brain parasite toxoplasma. But in healthy, non-pregnant individuals, the parasite just sits there with “long-term, potentially lifelong residence in the brains of healthy individuals and animals”—kept at bay by our immune system—“without any significant clinical consequence,” and, as such, “chronic toxoplasma infection has been viewed as a benign condition.” Until now, that is.