Bacterial meningitis is a disease that affects your central nervous system. It’s characterized by inflammation around your brain and spinal cord that leads to dangerous — and sometimes deadly — pressure in this area. Bacteria, viruses, and some fungi can all cause meningitis.
In cases of bacterial meningitis, the inflammation comes from a bacterial infection in your body. Since many different bacteria can cause meningitis, your doctor needs to learn which caused your case so they can provide the proper treatment.
Certain bacteria are more likely than others to cause meningitis at any given age. The most frequent bacterial causes in each age group are as follows:
- The most common bacterial sources in newborn infants are Group B Streptococcus, S. pneumoniae, L. monocytogenes, and E. coli.
- In older infants and young children, the most common bacterial sources are S. pneumoniae, N. meningitidis, H. influenzae, group B Streptococcus, and M. tuberculosis.
- In teens, common bacterial sources are N. meningitidis and S. pneumoniae.
- In older adults, the most common bacterial sources are S. pneumoniae, N. meningitidis, H. influenzae, group B Streptococcus, and L. monocytogenes.
How do you get bacterial meningitis?
Person-to-person contact is the most common way to pick up the bacteria that cause meningitis. But the spread can depend on the particular underlying bacteria. In general, these bacteria are spread through:
L. monocytogenes is spread through food. Group B Streptococcus and E. coli can also be spread to newborns from their mothers during birth.
Many people can come into contact with pathogens that cause meningitis but never become infected or develop the disease. Around 10% of the population never become sick even when they are infected.
These people can act as carriers for bacterial meningitis. They harbor small amounts of dangerous bacteria in their bodies and can pass them on to others.
The exact reason why some people develop meningitis when most don’t is unclear. We need more research to understand the exact causes of this disease.
Who is most at risk for developing bacterial meningitis?
People in certain risk categories are more likely to get meningitis. High-risk factors include:
- Specific age groups. Infants under one year of age and young adults between the ages of 16 and 21 are most at risk for developing meningitis.
- Global locations. Particular regions of the world have higher rates of meningitis than others and higher rates of the bacteria that cause meningitis. Sub-Saharan Africa during the dry season and Mecca during heavy pilgrimage are two areas with higher than average rates. Be aware of the risk if you plan on traveling to any of these areas of the world.
- Underlying conditions. People with compromised immune systems are more likely to get meningitis, including cases of HIV infection. This is also true if you no longer have a spleen.
- Large groups. Meningitis is most commonly spread in large, prolonged group settings like schools and college campuses. The CDC recommends additional vaccinations if three or more people get meningitis in one of these defined areas.
- Microbiology work. Some microbiologists come into contact with the bacteria that cause meningitis on a daily basis. If you interact with these bacteria as part of your job, you’re more at risk of developing meningitis.
How can you prevent bacterial meningitis?
The best way to prevent meningitis is to get vaccinated for as many causal bacteria as possible. The available vaccines that help protect you against bacterial meningitis include:
- Meningococcal vaccines. There are two main types of these vaccines available in the U.S. They’re effective against N. meningitidis.
- Pneumococcal vaccines. Two main types of these are approved for use in the U.S. They’re effective against S. pneumoniae.
- Haemophilus influenza serotype B (Hib) vaccines. These protect against Hib.
Keep in mind that vaccines don’t protect against all of the bacteria that cause meningitis. They also aren’t available for the most common cause of viral meningitis: non-polio enteroviruses.
When should you call your doctor?
Bacterial meningitis can begin suddenly, and symptoms can quickly get worse. It can be fatal or lead to permanent disabilities if left untreated for too long. Since a fast response can be life-saving, it’s best to contact your doctor as soon as you suspect that you or your child has meningitis.
Signs can include:
- Cold-like symptoms with a stiff neck
- High fever
- Feeling confused and sleepy
- Bruises all over your skin
Children can also be irritable, cry frequently, and their heads may swell.
Meningitis can be contagious, so you should also contact your doctor if you or your child has been in contact with someone who has the disease.
Health Solutions From Our Sponsors
Centers for Disease Control and Prevention: "Bacterial Meningitis," "Meningococcal Vaccination: What Everyone Should Know," "Pneumococcal Vaccination: What Everyone Should Know."
District of Columbia Department of Health: "Viral Meningitis Fact Sheet."
Johns Hopkins Medicine: "Bacterial Meningitis."
National Organization for Rare Disorders: "Meningitis, Bacterial."
NHS: "Causes Meningitis."
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