Health officials are warning about an unusual cluster of syphilis infections that strike the eyes, with six cases reported in Washington state since mid-December, including four in King County. Two people have been blinded by the disease. That’s an unusually high number of cases of ocular syphilis, which affects fewer than one in every million people in the general population each year, according to Dr. Russell Van Gelder, chair of the ophthalmology department at the University of Washington. Even among people with syphilis, ocular disease is detected in perhaps 10 percent of patients, he added.

The King County cases are all men, including three who report having sex with other men, the group most affected by syphilis in the region. Three are HIV-positive; people with HIV are often infected with syphilis, too. Read more via the Seattle Times