Semen may have been hiding a deadly secret. It turns out that sperm can host at least 27 different viruses, incorporating a diverse range of the infectious agents, and potentially playing a bigger role in the spread of diseases than we previously thought.
The discovery came after the news broke that the Zika virus can survive in semen for up to six months after infection. This finding inspired a pair of researchers from the University of Oxford to look at what other viruses can survive in sperm but they found little work on the subject.
So they ran a search through the literature on the link between viruses and semen, sperm, and seminal fluid, and discovered to their surprise that there were quite a few examples. It turns out that there are at least 27 different viruses that have been reported in semen and at least 11 that are able to survive in the testes. These findings were published in the journal Emerging Infectious Diseases.
We all know that some viruses, such as HIV and hepatitis, can be spread through semen, but the results threw up a whole host of other viruses which we know less about. The diverse range of families that these viruses derive from suggests that their ability to live in the testes and the male reproductive tract is unlikely to depend on specific or conserved mechanisms within the viruses.
The authors do, however, note that there may be other factors influencing whether or not a guy is harboring viruses in his semen. For example, if a person is immunosuppressed from another infection, this could allow viruses to survive. Other sexually transmitted infections might even play a role. As this latest study was simply a literature analysis, we still don't know for sure.
The analysis could not determine whether or not all the viruses detected in semen are sexually transmitted, but it does raise some important questions about the role sperm may have in spreading infections throughout a population, something that has generally been overlooked. The results also suggest that some of these viruses are able to alter the DNA of sperm meaning that virus-induced mutations could be passed on to a man's children.
Therefore, the researchers are warning that far more work should be carried out to ascertain exactly whether, and if so how, these viruses found in the semen and testes can remain viable and infectious, and hence if they can be sexually transmitted.
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