The U.S. Centers for Disease Control and Prevention and the Florida Department of Health are urging men who have sex with men to get vaccinated for meningitis amid "one of the worst outbreaks of meningococcal disease among gay and bisexual men in U.S. history."

Twenty-six cases and seven deaths from meningococcal disease have been recorded in Florida in recent weeks, of which 24 cases and six deaths were in gay and bisexual men.

The CDC said in a statement that the outbreak of meningococcal infections was "primarily among gay, bisexual and other men who have sex with men, including those living with HIV. Recent data show that about half of the cases associated with this outbreak are among Hispanic men.

"This outbreak is mostly affecting people who live in Florida, but has also affected some people who have traveled to Florida."

Stock images: a map of Florida and a rendering of the meningococcal bacterium next to neuron cells.ISTOCK / GETTY IMAGES PLUS

Meningococcal infections include meningitis (an infection of the meninges membrane lining of the brain and spinal cord) and bloodstream sepsis. If left untreated, both these conditions can kill within days. Two serogroups—subspecies of the meningococcal bacteria—known as B and C have been recorded in the Florida outbreak.

Serogroup C is the strain currently affecting large numbers of gay, bisexual and other men who have sex with men. There is also an outbreak in Leon County of serogroup B meningococcal disease among college students.

The bacteria is spread through prolonged close contact involving sharing respiratory or throat secretions, such as saliva or spit. Although it is not classified as a sexually transmitted disease because it is not transferred via sexual bodily fluids such as semen, it can be spread through sex or kissing.

"Getting vaccinated against meningococcal disease is the best way to prevent this serious illness, which can quickly become deadly," said Dr. José R. Romero, director of the National Center for Immunization and Respiratory Diseases, in the CDC statement.

"Because of the outbreak in Florida, and the number of Pride events being held across the state in coming weeks, it's important that gay and bisexual men who live in Florida get vaccinated, and those traveling to Florida talk to their healthcare provider about getting a MenACWY vaccine."

The MenACWY vaccination protects against serogroups A, C, W and Y, while the MenB vaccine is recommended for serogroup B. People with HIV are most vulnerable to meningococcal infections, as they are often immunocompromised. The CDC advises people with HIV to receive a meningococcal conjugate ACWY vaccine, as well as booster doses of this vaccine throughout life.

Neisseria meningitidis bacteria are responsible for these outbreaks, but many people have the bacteria living inside them without getting ill. About 1 in 10 people have these bacteria in the back of their nose and throat, but they will not get sick unless the bacteria gets into the bloodstream or the lining of the brain. Serogroups B, C, and Y are the most commonly seen in the U.S./agencies