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Human semen can host up to 27 different viruses

When scientists discovered that the Zika virus can survive in semen for up to 6 months, people exposed to the disease—especially those hoping to have children—were horrified. It’s now known that the virus can be sexually transmitted up to 41 days. Now, a new meta-analysis has found that 26 other viruses can also live in human semen and go on to infect the bloodstream. Those include the viruses that cause Ebola, HIV, hepatitis B, and herpes. After reviewing more than 3800 scientific publications, the authors also found evidence that at least 11 viruses can live in the testes, including those that cause influenza, dengue, and severe acute respiratory syndrome. These viruses could potentially be found in semen, too, the authors say. Though not all 27 viruses are capable of person-to-person transmission, they can have other serious consequences, like reducing fertility or increasing the risk of acquiring a sexually transmitted disease. Some of these viruses can even cause mutations in the DNA of sperm, which could then fertilize an egg and pass along the virus-induced mutations to future generations. The findings, published last week in the Centers for Disease Control and Prevention’s Emerging Infectious Diseases journal, suggest that more viruses can live in semen than previously thought. But the authors warn that far more research is needed to understand how and whether the viruses can be sexually transmitted and exactly which viruses remain viable in semen, for how long, and at what concentrations.