permutation test

The latent toxoplasmosis is usually considered to be asym ptomatic, however, this paradi gm has never been rigorously tested. Here we searched for symptoms of de terioration of physical health (decrease of weight) in infected people by analysis o f clinical records of 758 women tested for toxoplasmosis in the 16th week of gravidity. Toxoplasma -positive women have a lower body weight in the 16th week of gravidity (p = 0.02) than Toxoplasma -negative women. Moreover, a negative correlation be- tween weight and the duration of toxoplasmosis was found in a subset of 174 Toxoplasma -positive women (p = 0.04), suggesting that slow and cumulative effects of latent toxoplasmosis, rather than a transient eff ect of acute toxoplasmosis, are responsibl e for the decreased weight of infected subjects. Longer duration of gr avidity estimated from the date of last menstruation in the set of Toxoplasma -positive women in the 16th week of gravidity estimated with ultrasonography (p = 0.04) suggests a possibility of retarded foetal growth in Toxoplasma -positive women. The prevalence of latent toxopl asmosis is extremely high. Therefore, even its mild symptoms such as the decreased body weight in Toxoplasma- positive pregnant women mi ght in fact indicate an unrecognized serious public health problem.