By the numbers: an increasing mortality rate.
The disease is caused by infection with a bacterium called Neisseria meningitidis. According to the Centers for Disease Control and Prevention, 422 cases of invasive meningococcal disease were reported in the United States last year, the highest number since 2014.
But as of Monday, 143 cases have been reported to the CDC this year, 62 more than the number of cases reported last year during the same period.
The disease is extremely dangerous. Even with adequate treatment, 10 to 15 percent of patients who develop meningococcal disease will die. Many recent cases have been caused by an unusual strain of N. meningitidis called ST-1466. This strain caused 17 deaths among 94 patients whose outcomes are known, for a mortality rate of 18%.
Survivors of meningococcal disease may end up with long-term disabilities, deafness, amputations, or brain damage.
The Mystery: What's Causing the Epidemics?
Most of those affected by the recent outbreaks were people of color and adults between the ages of 30 and 60.
Other individuals susceptible to infection include people living with HIV, who represent 15% of patients; individuals who have had their spleen removed; people with sickle cell anemia; and patients with some rare immune conditions.
A meningitis vaccine that protects against four of the six types of N. meningitidis — including group Y, which includes ST-1466 — is recommended for adolescents and those with medical conditions such as HIV. Most older adults have not received the vaccine.
In Virginia, which has had 35 cases of meningococcal disease and six deaths since the summer of 2022, public health officials have not found an epidemiologic link to explain the outbreak, said Dr. Laurie Forlano, the state's epidemiologist.
“We're always trying to find that golden ticket of common risk factors,” Dr. Forlano said. “Were they all at the same party or family event together? Were they all in a certain facility? Are there social networks that share? That's not really the case here.”
The disease is not spread through casual contact, but through activities that involve exposure to saliva or respiratory or throat secretions – kissing, for example, or sharing food and drinks or cigarettes.
A ticking clock: treatment must occur quickly.
The infection can cause meningitis, an inflammation of the membranes covering the brain and spinal cord. Typical symptoms include fever, headache, stiff neck, vomiting, sensitivity to light, and altered mental status.
The bacteria can also invade the bloodstream, a complication called sepsis, which appears to be the most common consequence of current serogroup Y cases. Symptoms include fever and chills, fatigue, vomiting, cold hands and feet, severe aches and pains, diarrhea , rapid breathing, and, in later stages, a dark purple rash.
Symptoms can rapidly intensify and become life-threatening within a few hours. Antibiotics should be administered promptly.
“With meningococcal disease, people's thoughts go to meningitis, which is a very scary condition,” Dr. Forlano said. “But the point we're trying to make to the clinical community is that these cases present differently than we're used to. So, hey, think about this.
Despite the risk, he stressed that the disease remains rare. “The threat to the general public is low,” she said.