Even after six weeks, the testes stayed the same and did not return to their original size. Because of this, there was a large decrease in the amount of sperm and the levels of testosterone being produced. With less sperm, male mice that had been affected with the Zika virus in the past or present, were less likely to impregnate a female.
After the male mice no longer contained the virus within their bloodstream, the consequences remained. Researchers believe that this damage is irreversible. The virus destroys the Sertoli cells, which are used to nourish the sperm cells and act as a barrier. Unfortunately, these cells are not capable of regenerating.
Human males that have had the Zika virus did not report any decrease in testosterone, sperm, or smaller testes, but that does not mean that it is not happening within their bodies. Men will not realize their decrease in reproduction rates until they want to have children, and that could be years. Also, the shrinkage in size of their testes may be so small that it is not noticeable to themselves. This reproductive affect from Zika could be a major problem within the future. More research needs to be performed on how Zika affects males, not just pregnant females.