Zika virus devastates testes of mice, study finds

NEW YORK — Zika virus ravages the testes of male mice, sharply reducing sperm counts and fertility, according to a study that raises a new specter about its threat to people.

Experiments found testes of infected mice shrank about 90 percent by weight, while their output of useful sperm fell by three-quarters on average, and often more.

Shannan Rossi, who studies Zika in mice at the University of Texas Medical Branch in Galveston, noted that the researchers had suppressed the animals’ immune system defense against the virus.

Zika, which is transmitted by the bite of a tropical mosquito, is such a mild disease in people that most who get it don’t even know they are sick.

[...] it can cause serious birth defects if women are infected while pregnant, so health officials have been concerned mostly with helping women who are pregnant or about to become pregnant avoid the disease.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases in Bethesda, Md., said the study alerts researchers to look for effects in men.