An inexpensive method to measure latent toxoplasmosis and its behavioral consequences.

An estimated 2.4 billion humans are affected by the protozoan Toxoplasma gondii, which causes one of the most common infections influencing human behavior and cognition. The infection and its effects are severely underresearched, because the diagnosis is costly and time-intensive, preventing widespread testing, in particular in less-than-wealthy regions. Psychological methods such as response time analysis could circumvent these problems and facilitate more intensive research. We propose a psychological diagnostic method for latent toxoplasmosis using response times, hence enabling large-scale tests of psychological, psychiatrical, and behavioral effects. A clinical trial (N = 119) showed that the method is sensitive (92 %) and specific (97 %) compared to testing for Toxoplasma IgG Antibodies (p < 0.0001, w = 0.85). A representative UK survey (N = 2020) using this method confirmed previously-hypothesized behavioral effects and uncovered previously-unknown effects of latent toxoplasmosis infections which are relevant and pervasive, both psychologically (increase in risky behaviors, depression, anxiety, and stress) and economically (decrease in yearly income of 2500 GBP; decrease in employment of 11 %).