Just about a month after Washington State reported an increase in ocular syphilis in the men who have sex with men (MSM) population, San Francisco health officials are reporting a cluster of 7 cases since December 2014.

Treponema pallidum spirochete/CDC

The health department says five of the affected individuals were MSM and six were HIV-infected.

The San Francisco Health Department is advising physicians to test for syphilis in patients presenting with visual complaints, as well as in patients presenting with genital, oral, or anal ulcers, or rash. The most common eye finding in ocular syphilis is uveitis.

In addition, health care providers should ask patients with known or suspected syphilis about changes in their vision and about headache and changes in their hearing (including hearing loss or tinnitus) in order to identify persons who may have ocular syphilis, otologic syphilis, or neurosyphilis.

Evidence suggests that certain strains of Treponema pallidum, the bacterium that causes syphilis, may be more likely to cause central nervous system (CNS) disease. It is not known whether there are strains of T. pallidum that have a greater likelihood of causing ocular infections, but the cluster of cases raises this possibility.

Syphilis is a sexually transmitted disease caused by the bacterium Treponema pallidum. Symptoms of syphilis are easy to miss, and easy to mistake for something else. Symptoms in each stage look different, ranging from painless sores that go away to a rash to no symptoms at all. But syphilis in the later stages causes paralysis, dementia, blindness, deafness, heart failure and even death.