We are very aware of the effects Zika virus has on fetuses and pregnant women, but a new study from Washington University in St. Louis published Monday in the journal Nature, suggests that Zika may also interfere with a man's ability to reproduce.
During the study, male mice were infected with Zika and within one week the virus had traveled to their testicles and there was some inflammation observed. After two weeks, the testes had shrunk, their internal structure was collapsing and many cells were dying.
After the third week, researchers found the mice's testicles had shrunk to one tenth their original size, they had a reduced level of sex hormones and reduced fertility. Female mice were paired with both Zika infected and uninfected male mice, and the females mated with infected males were four times less likely to get pregnant than those mated with uninfected males.
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Six weeks later, even after the virus was cleared from the mices' bloodstream, their testicles did not heal. The structure of testes are dependent on Sertoli cells, which nourish developing sperm cells but do not regenerate.
Michael Diamond, MD, PhD, a co-senior author on the study and the Herbert S. Gasser Professor of Medicine said in a press release, "We don't know for certain if the damage is irreversible, but I expect so, because the cells that hold the internal structure in place have been infected and destroyed."
He added, "While our study was in mice - and with the caveat that we don't yet know whether Zika has the same effect in men -- it does suggest that men might face low testosterone levels and low sperm counts after Zika infection, affecting their fertility."
Currently, the Centers for Disease Control and Prevention recommend that men who have traveled to places with a known presence of Zika use condoms for at least six months afterward because the virus can persist in their semen for several months.
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