Zika Makes Mouse Testicles Smaller, Raises Questions About Male Fertility In Humans

Nov 1, 2016

South Floridians have one more reason to avoid the Zika virus—and this one’s especially for the men out there: New research using mouse models shows the Zika virus can shrink testicles.

“We started looking at the placental barrier and seeing if the virus could cross there,” says Dr. Jen Govero, a scientist who worked on the study at Washington University in St. Louis.

Govero says part of what makes Zika unusual is that it has a tendency to get past what are known as “immune privilege sites.” These are places in the body that act as natural roadblocks to most viruses--like the placental barrier, the blood-brain barrier and the blood-testes barrier.

“The body tries and protects more against viral and bacterial infection because there’s precious cargo there,” says Govero.

But the Zika virus is managing to break through all these safeguards.

In the mice, Zika infection decreased testes to a tenth the average size. The mice’s testosterone dropped. And the virus showed up in their sperm.

“This, I think, will be an eye-opener to also look at the effects this could have on men and their fertility,” says Govero.

According to Govero, it could be months or more before researchers know what this means for humans. In the meantime, it’s one more reason for men to pay attention to mosquito prevention tips like wearing long sleeves and bug repellent.