How and why Toxoplasma makes us crazy.

For a long time, a latent toxoplasmosis, the lifelong presence of dormant stages of Toxoplasma in various tissues, including the brain, was considered harmless for immunocompetent persons. Within the past 10 years, however, many independent studies have shown that this parasitic disease, with a worldwide prevalence of about 30%, could be indirectly responsible for hundreds of thousands of deaths due to its effects on the rate of traffic and workplace accidents, and also suicides. Moreover, latent toxoplasmosis is probably one of the most important risk factors for schizophrenia. At least some of these effects, possibly mediated by increased dopamine and decreased tryptophan, are products of manipulation activity by Toxoplasma aiming to increase the probability of transmission from intermediate to definitive host through predation.