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Semen in the Spotlight

​​During pregnancy, women may be more susceptible to infection with a range of viruses. Certain viruses pose a threat to embryos, foetuses or neonates, as well as to women themselves. For that reason, infection prevention receives a lot of attention, both preconceptionally, prenatally and perinatally. The vaccination status of women who want to have a child is checked, and during pregnancy, their serum is tested on a series of viral infections. Women also receive extensive instructions on how to prevent infection with viruses (Cytomegalovirus, Zika et cetera), often tailored to specific risks that exist in the region where they live.

Sofar, men have been a bit out of sight in many of these preventive measures, although one possible way for a woman to contract a virus, is through sexual intercourse. In that respect, this new literature study is relevant. It shows that 27 viruses that can cause viremia (presence of virus in the blood), can be found in human semen. Among these, there are quite a few that can be relevant for midwifery practice as they may be transmitted from the mother to an unborn child during pregnancy or delivery. Apart from the obvious HIV, Hepatitis B and C, Cytomegalovirus, Varicella zoster virus and several strains of Human herpes virus were detected in semen.

​​It is important to note some things here. Firstly, for 14 of the 27 viruses, no evidence was found of sexual transmission within the same cohort. Secondly, some of the viruses that at first sight may seem less relevant to perinatal health, may be sexually transmitted; the possible effect on mother or child remains unclear. And thirdly, because of the research methods used in some of the investigated studies, the presence of a virus in the semen does not always mean that it is able to replicate or to infect.

So while the “presence of viruses in semen is probably more widespread than currently appreciated, and the absence of virus in genital secretions should not be assumed for traditionally non-sexually transmitted viruses”, the authors rightly note there are still crucial questions begging for an answer: “which viruses are shed and remain viable in semen, for how long, and at what concentrations?”

So have we been overlooking semen as one of the possible sources of viruses causing birth defects and congenital disabilities? Let’s hope researchers will be able to close the knowledge gaps and provide the answers, as they are bound to have “implications for risks for sexual transmission and, therefore, embryonic infection, congenital disease, miscarriage, and effects on epidemiologic and transmission models”.

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Salam, A.P. & Horby, P.W. (2017) The breadth of viruses in human semen. Emerg Infect Dis. 23(11). See:

Photo credits

Photo 1: CCBY Grace Hebert, Sperm Graffiti. See:

Photo 2: CCBY Yale Rosen, CMV infection, Basophilic nuclear inclusions. See:

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