Six men in the Chicago area have been diagnosed with meningitis since June—one has died, and a seventh possible case is awaiting test results—all of whom were men who have sex with men (MSM), reports the Chicago Tribune.

Chicago Health Department officials are recommending all gay and bisexual men get vaccinated, as well as transgender women who have sex with men. Previous recommendations from the health department and the Centers for Disease Control and Prevention (CDC) suggested recommendations for HIV-positive men who have sex with men.

The outbreak has disproportionately affected African-American men.

Meningitis results from bacteria that attack the membrane surrounding the brain and spinal cord. According to the paper, the disease spreads “through the sharing of saliva and spit, such as in kissing or sexual contact; or by sharing drinks, cigarettes, marijuana or other smoking devices. Those diagnosed with the illness are treated with antibiotics.”

The outbreak is occurring as the LGBT community celebrates Pride, traditionally in June. Free vaccinations are being offered at Chicago’s Pride events June 20 through 28, and they will be available at several locations in the city.

Meningitis outbreaks have occurred among other MSM populations, for example last fall among three HIV-positive New Yorkers. In light of Chicago’s outbreak, New York City’s health department sent out a meningitis alert also recommending vaccinations and stressing that the disease can spread “by prolonged close contact with nose or throat discharges from an infected person or carrier. Examples of prolonged contact include living in the same household or intimate activities, like kissing and sexual contact.”

For a first-person look at this issue, read Kevin Cummines’ op-ed “Two Pills Saved My Life. Two Shots Could Have Saved His.”