Researchers have for the first time determined that the Zika virus can be sexually-transmitted between men, according to officials from the U.S. Centers for Disease Control and Prevention (CDC). CDC officials said this mode of transmission “might contribute to more illness than was anticipated when the outbreak was first recognized.” The CDC published its study in the Morbidity and Mortality Weekly report.

“Such cases highlight the need for clinicians to remain vigilant for and continue reporting any suspected cases of Zika virus infection to their state or local health departments,” according to the report. “This includes suspected infections in symptomatic persons without travel history, but who report unprotected sexual contact with a person who has traveled to an area with active Zika virus transmission.” FULL REPORT