Syphilis infections cases in Japan have been on the rise in recent years.
As of October 29, more than 12,000 cases were reported among adults this year. This is the fastest rate of increase since comparable data became available in 1999.
Kawana Kei, a chief professor at Nihon University's School of Medicine and an expert on syphilis, says infections should be treated before pregnancy to avoid passing them on to newborns.
"Even if you get treatment after you notice you are infected with syphilis during pregnancy, there is still a possibility that your baby will develop congenital syphilis," Kawana says. "It's important to treat infections before you become pregnant."
Congenital syphilis can cause rashes, and abnormalities in bones shortly after birth. The infected children can develop symptoms such as inflammation of the eyes and hearing loss in a few years, even if they don't have symptoms when they are an infant.
Kawana says both men and women who believe they may be infected should get tested.