There are four different groups of meningococcal bacteria known to circulate in the United States — B, C, W and Y. The CDC says that in 2023, there were 422 cases of disease caused by these bacteria reported in the United States, the highest number reported since 2014. Most of them were caused by a particular strain, ST-1466, which is in the Y subgroup.

So far, 2024 is on track to top that number. To date, 143 cases have been reported in the United States — almost 80% more than had been reported at the same point in 2023.

The CDC says most people being diagnosed with this particular are adults ages 30 to 60.A disproportionate number of cases, 63%, are among Black peopleand 15% are in people who have HIV.

The bacteria can spread from person to person through the exchange of respiratory and throat secretions, and typically occurs via kissing, coughing, sneezing or living in close contact with others who are infected.

The US Centers for Disease Control and Prevention said in a new health alert that these infections, which are caused by a certain strain of Neisseria meningitidis bacteria, may present with unusual symptoms. In the cases identified so far this year, about 1 in 6 people have died, a higher fatality rate than they typically see with meningococcal infections.