Between 20 and 60 % od the population in most countries are infected with the protozoan Toxoplasma gondii. Subjects with clinically asymptomatic latent toxoplasmosis differ from those who are Toxoplasma-free in several behavioural parameters.
Case control studies cannot decide whether these differences already existed before infection or whether they were induced by Toxoplasma. Here we searched for morphological differences that could be induced by the parasite (body weight, body height, body mass index, waist-hip ratio), or could rather correlate with natural resistance to parasitic infection (fluctuating asymmetry, 2D:4D ratio).
We found Toxoplasma-infected men to be taller and Toxoplasma-infected men and women to have lower 2D:4D ratios previously to be associated with higher prenatal testosterone levels. These results suggest that some of the observed differences between the infected and non-infected subjects may have existed before infection and could be caused by the lower natural resistence to