When the Zika virus first burst onto the scene in South America, pregnant mothers were found to be most at risk from getting the disease through mosquito bites. But as the epidemic evolved, further research uncovered that the virus is not only spread by the insects, but also sexually.
Now, research suggests that the virus may also impact infected men and could potentially lead to infertility and even testicular atrophy, or shrinkage. Transmission via mosquito is still thought to be the main way in which the virus spreads, but the fact that the virus can persist in the semen of infected men for at least six months after infection is particularly worrying for healthcare professionals and public health organizations trying to contain the disease.
The new study, published in Science Advances, looked at the impact of the virus over a period of time in the testes of male mice, and confirmed what other researchers have found. While it was known that the virus could persist in the semen of men months after the infection had been cleared from the blood, it was unclear how it affected the testes. It turns out that after 21 days from when the mice were first infected, the virus continued to replicate in their testicular cells.
They found that the virus specifically persisted in a part of the testes known as the epididymis, which is responsible for moving the sperm from the testes to the urethra. This fits in with what was previously known about how the virus is sexually transmitted from males to females. But in addition to this, they also discovered that after 21 days, the size of the testes of infected mice were significantly smaller, having undergone testicular atrophy. This is most likely having further impacts on the fertility of the males.
While the initial international emergency of Zika has been declared over, that does not mean that the virus has simply gone away. In fact, the pathogen that can cause neurodevelopmental problems in children is more than likely here to stay, for the time being at least. To that end, researchers have been hurriedly working over the last few years to identify, test, and manufacture a vaccine and cure, with some gains.
How the virus persists in the environment is critical for how public health organizations deal with the disease and contain it. The fact that it may be able to reside in the testicles of men for months after infection, and even cause infertility, is vital knowledge in the fight against Zika.