Bacteria That Cause Meningitis Are Spreading Again, C.D.C. Warns

The News

Federal officials are warning health care providers to be on the lookout for invasive meningococcal disease, a rare but potentially deadly illness that has increased in prevalence in recent years and requires prompt treatment with antibiotics to prevent long-term disability or death.

By the Numbers: A rising fatality rate.

The illness is caused by infection with a bacterium called Neisseria meningitidis. Last year, 422 cases of invasive meningococcal disease were reported in the United States, the highest number since 2014, according to the Centers for Disease Control and Prevention.

But as of Monday, 143 cases have been reported to the C.D.C. so far this year, 62 more than the number of cases reported last year during the same period.

The illness is extremely dangerous. Even with appropriate treatment, 10 to 15 percent of patients who develop meningococcal disease will die. Many recent cases were caused by an unusual strain of N. meningitidis called ST-1466. This strain caused 17 deaths among 94 patients whose outcomes are known, a fatality rate of 18 percent.

Survivors of meningococcal disease may be left with long-term disability, deafness, amputations or brain damage.

The Mystery: What’s causing the outbreaks?

A majority of people affected in the recent outbreaks were Black people and adults ages 30 to 60.

Others who are susceptible to the infection include people living with H.I.V., who account for 15 percent of patients; individuals who have had their spleens removed; people with sickle cell disease; and patients with certain rare immune conditions.

A meningitis vaccine that protects against four of six N. meningitidis types — including group Y, which includes ST-1466 — is recommended for adolescents as well as those with medical conditions like H.I.V. Most older adults have not received the vaccine.