Neisseria meningitidis is the most common cause of bacterial meningitis. It’s classified into 12 serogroups based on the composition of its polysaccharide capsule (a protective layer made of sugar molecules).
However, six serogroups are primarily responsible for most of the serious cases of meningococcal disease worldwide. These serogroups are A, B, C, W, X, and Y.
The types of these serogroups differ across regions and change with time. For instance, serogroup A has historically been a significant cause of outbreaks in parts of sub-Saharan Africa, stretching from Senegal to Ethiopia. But after mass vaccination with the MenAfriVac vaccine, the number of cases significantly decreased.
Knowing how often these serogroups show up is crucial for deciding where and how to vaccinate people to stop meningococcal disease from spreading.
Serogroup B is the most common serogroup of Neisseria meningitidis and is responsible for meningitis worldwide. This serogroup has been identified as the primary cause of serious cases of meningococcal disease in many regions, including the Americas, Europe, and Australia.
Yes, the serogroup can affect the severity of meningococcal disease. For example, serogroup W has been linked to more deaths than other serogroups. But after considering certain factors such as age and symptoms, the differences in the number of deaths within 30 days become smaller.
In general, the overall severity of meningococcal disease depends on various factors, including serotype, age, symptoms, and any existing health problems.
No, serogroup doesn’t influence treatment. Treatment for meningococcal disease typically involves antibiotics, such as ceftriaxone or ciprofloxacin, regardless of the serogroup.
Although these antibiotics are effective with most serogroups, antibiotic-resistant Neisseria meningitidis serogroup Y cases have been identified in the United States. In these cases, treatment may have to be modified.
Knowing the serogroup is crucial for prevention strategies, such as vaccines, since they target specific serogroups. For example, the MenACWY vaccine covers serogroups A, C, W, and Y, while the MenB vaccine is for serogroup B.
Dr. Avi Varma is an ABMS board certified family medicine physician and public health advocate working for a nonprofit fighting the HIV epidemic in Atlanta, Georgia. Dr. Varma is an HIV Specialist™ (AAHIVS), certified through the American Academy of HIV Medicine.