** Institute of Haemathology and Blood Transfusion, U nemocnice 1, 120 00 Prague, Czech Republic

The protozoan Toxoplasma gondii is one of the most widespread human parasites. It has been estimated that 30-60% of total population is currently infected with this parasite. The most usual form of infection in immunocompetent patient is latent toxoplasmosis, which is conventionally considered as asymptomatic. However, recent studies show that the infection is associated with specific changes in some personality factors. In this study we focused our attention on the influence of the infection on psychomotor performance. A total of 116 subjects (69 men, 47 women) were tested for toxoplasmosis and underwent a computer version of reaction time test. The infected subjects reacted significantly slower in the second and third minute of the test (F(1,113)=7.62; p=0.007; respectively F(1,113)=4.81; p=0.03). Also the total average reaction time of the infected subjects was significantly longer in comparison with the noninfected subjects (F(1,113)=5.37; p=0.022). In 60 Toxoplasma-positive subjects there was found out that reached reaction time in the first (Kendall tau=-0.175; p=0.038) and second minute of the test (Kendall tau=-0.156, p=0.048) and also the total average reaction time (Kendall tau=-0.183, p=0.029) was positively correlated with the length of infection (estimated from the level of antibody titers).