Influence of Toxoplasma gondii Infection on Male Fertility: A Pilot Study on Immunocompetent Human Volunteers

Background: This study was conducted to investigate the influence of Toxoplasma gondii infection on spermatic and hormonal parameters in a pilot sample of immunocompe­tent human male subjects. Methods: This cross sectional, observational pilot study on 60 immunocompetent hu­man male subjects aged between 18 and 60 yr old was conducted between 2012 -2013. Blind evaluation of serological markers of past T. gondii infection (TOX-IgG, TOX-IgM) was performed, along with individual spermiograms and determinations of folli­cle-stimulating hormone (FSH) and testosterone serum levels. Results: The overall prevalence of past T. gondii infection in the investigated immunocom­petent male subjects was 25%. No statistically significant influence of T. gondii infection on sperm characteristics (ejaculate quantity, sperm count, motility, morphol­ogy) and serum levels of FSH or testosterone were found. Among possible predictors of a modified spermiogram studied by multiple logistic regression along with the T. gondii infection (age, smoking, alcohol consumption, fertility influencing malfor­mations, infections, trauma or medication), only the presence of varicocele in the medi­cal history of the studied subjects was found to significantly participate in the predic­tion of a modified spermiogram (P=0.0154). A necessary sample size of 994 subjects was computed in order to achieve a test power of 0.8 (80%) to discriminate an effect size of 8.89% estimated by our pilot study. Conclusions: Although our investigation did not demonstrate an influence of latent T. gondii infection on spermatic and hormonal parameters of immunocompetent male hu­mans, the absence of such an influence cannot be affirmed, due to the limited sample size of our pilot study.