Small pests and bugs can inflict a surprising amount of damage. A homeowner who finds termite damage is likely to spend upwards of $3,000 to repair it. But creepy crawlers can do more than damage a house — the Zika virus, which is carried certain species of mosquitos, has been found to damage male fertility (in mice, anyhow).
Researchers have found that the Zika virus can get into the testes of mice, effectively shrinking and damaging them so severely as to result in a sperm production drop.
There is no evidence that it could do the same to human males, and scientists say that much more study is needed.
“This is the only virus I know of that causes such severe symptoms of infertility,” said Dr. Kelle Moley, one of the leaders of the study, and a fertility specialist at Washington University in St. Louis.
“There are very few microbes that can cross the barrier that separates the testes from the bloodstream to infect the testes directly,” she said.
Some well-known causes of male infertility include mumps and the ebola virus. Zika is well known for being shown to cross the placenta and infect human fetuses, and in such cases causes severe brain damage and other birth defects.
It is also known to cause a condition called Guillian-Barre syndrome, which damages the central nervous system in adults, causing brain inflammation.
Another thing researchers already know about Zika — it can get into the semen and be sexually transmitted.
In the mice used during the study, the virus stayed in their semen for a significant period.
“What we found was that by day seven you could already detect the virus there and it was cleared by day 21,” Moley said. “But you could see a progressive destruction of the cells in the testes. So by day 21 the testes was about a tenth of the size of what it originally was. As a result there was no sperm.”
The mice in the study might not be the best reflection of the normal circumstances in which Zika is contracted, since their immune systems were repressed. However, researchers plan to continue their study on Zika-infected men.