Story highlights

Zika devastated the sperm count and fertility of male mice

Mice testicles shrunk to one-tenth of their normal size and did not recover

Zika can hide in men's sexual organs as well but more research is needed to see if it affects fertility

CNN  — 

If you’re a guy mouse, the news about Zika’s effect on your sex life couldn’t be worse.

Not only did male mice infected with the Zika virus have a tougher time getting females pregnant, their levels of sex hormones crashed, and their testicles shrunk by 90%, possibly permanently, according to new research by the Washington University School of Medicine in St. Louis.

Of course, these are mice, not men.

“We undertook this study to understand the consequences of Zika virus infection in males,” said co-senior author Dr. Michael Diamond, associate director of the school’s Center for Human Immunology and Immunotherapy Programs.

“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.”

“People often don’t find out that they’re infertile until they try to have children, and that could be years or decades after infection,” added co-senior author Dr. Kelle Moley, professor of obstetrics and gynecology at the Washington University School of Medicine. “I think it is more likely doctors will start seeing men with symptoms of low testosterone, and they will work backward to make the connection to Zika.”

Zika’s effect on men

It’s well-known that Zika can survive in the testes of some men long after the virus has cleared their blood and urine. One man harbored live virus in his testes for three months, and traces of the RNA that makes up Zika has been found in other men’s sexual organs for up to six months. That’s why both the Centers for Disease Control and Prevention and the World Health Organization have told men who have traveled to an area where Zika is active to use condoms for a full six months after exposure.