Preprints with The Lancet is part of SSRN´s First Look, a place where journals and other research experts identify content of interest prior to publication. These preprint papers are not peer-reviewed. Authors have either opted in at submission to The Lancet family of journals to post their preprints on Preprints with The Lancet, or submitted directly via SSRN. The usual SSRN checks and a Lancet-specific check for appropriateness and transparency have been applied. Preprints available here are not Lancet publications or necessarily under review with a Lancet journal. These papers should not be used for clinical decision making or reporting of research to a lay audience without indicating that this is preliminary research that has not been peer-reviewed. For more information see the Comment published in The Lancet, or visit The Lancet´s FAQ page, and for any feedback please contact preprints@lancet.com

16 Pages Posted: 4 Sep 2019

Abstract

Background: Toxoplasmosis is one of the most widespread human parasitoses in the developed countries. Toxoplasma gondii has been found in the ejaculate of various animals, including human. Sexual transmission of this zoonosis has been confirmed in several animal species but not in human. Nevertheless, a large part of infections in mothers of children with congenital toxoplasmosis cannot be explained by contact with any currently known risk factor, while high prevalence of toxoplasmosis has been observed in the fathers of children with this diagnosis. This indirect evidence supports the hypothesis of sexual transmission of toxoplasmosis in humans.



Methods: We compared the prevalence of toxoplasmosis in couples and analysed various risk factors for toxoplasmosis including the infection status of sexual partner. By comparing the risk factors for Toxoplasma infection in men and women, we tested the hypothesis of man-to-woman sexual transmission of toxoplasmosis. Findings The prevalence of toxoplasmosis in women with infected male partners (25·6%; n=156) was higher than the prevalence in women with uninfected male partners (18·2%; n=477; p=0·023). Partner's infection therefore seems to be a risk factor for infection in women (n=593; odd ratio=1·602; p=0·022) but not in men (n=573; odds ratio=1·064; p=0·816).



Interpretation: Our results support the hypothesis of sexual transmission of toxoplasmosis from men to women. The risk may seem relatively low, but transmission can occur during unprotected sexual intercourse, which may be the time of conception. Due to the risk of congenital toxoplasmosis, even a lower risk of infection than that observed in our study can represent a serious public health problem.



Funding Statement: Charles University Grant Agency (number 104218), Czech Science Foundation Grant (number 18-13692S), Charles University Research Centre program (number 204056) and RVO-VFN64165 from the Ministry of Health of the Czech Republic.



Declaration of Interests: The authors declare no competing interests.



Ethics Approval Statement: Informed consent was obtained from all participants. Blood samples for serological testing for toxoplasmosis were taken during a routine examination. This research has been repeatedly approved by Ethics Committee of General University Hospital in Prague (No. 384/16; 92/17) and by Institutional review board of Faculty of Science, Charles University (No. 2015/29).