A deadly strain of meningitis has infected eight people in Los Angeles County and killed three gay men, the Department of Public Health announced Thursday.

Among the eight who were infected with invasive meningococcal disease, three were HIV-positive and four were gay. According to The Los Angeles Times, the men who died were around the ages of 27 or 28 years old, and a few of the patients infected lived or socialized in West and North Hollywood.

“This does cause us some concern,” West Hollywood City Councilman Josh Duran told NBC News. “It’s not a sexually transmitted disease but it is casually transmitted through saliva droplets.” Meningitis can be spread through shared saliva and also from inhaling someone’s sneeze or cough droplets. People who are HIV positive are more vulnerable than those with stronger immune systems.

The medical director at the L.A. Gay & Lesbian Center, Robert Bolan, told The LA Times that “the important thing to understand is this is not an epidemic. But there’s a pretty strong signal that men who have sex with men, at least those who are HIV positive, are at increased risk for invasive meningococcal disease.”

In the past several months, meningitis outbreaks have occurred across several college campuses, including Princeton University and UC Santa Barbara. The particular strain at the college campuses could only be prevented with a certain vaccine that was not yet approved by the FDA, but the strain in L.A. County can be prevented by available vaccines.

Meningococcal disease is caused by the bacterium, Neisseria meningitidis, which is a common cause of bacterial meningitis and sepsis in the U.S., the Centers for Disease Control & Prevention says. When someone is infected with meningococcal disease, their protective membranes surrounding the brain and spinal cord (meninges) are inflamed and infected. Symptoms include migraine, fever, stiff neck, and nausea. According to the CDC, between nine and 12 percent of people who are infected with the disease die, and 20 percent of survivors experience lasting damage from the disease — such as hearing loss, neurologic damage, or amputation.

People who are more likely to be infected with meningitis are those who smoke, or who are HIV-positive, the CDC states. Antibiotics such as penicillin typically work as treatment once a person has been infected; otherwise, vaccines are available to prevent the disease.

L.A. County will be offering free vaccinations for people who don’t have health insurance; people can visit the department’s website to check out provider clinics.