Most meningitis is caused by bacteria and viruses that often live in our bodies. Usually these germs stay in the intestines or in the nose and throat, where they may or may not make us sick. But if they spread to the tissues (meninges ) that surround the brain and spinal cord, they cause inflammation. This inflammation is called meningitis.
The germs that can lead to meningitis are contagious, which means they can be passed from one person to another.
Viral meningitis is the most common and the least dangerous. It's caused by viruses, most often enteroviruses that live in the intestines. These viruses can be spread through food, water, or contaminated objects. Meningitis caused by enteroviruses occurs most often
in babies and young children.
Bacterial meningitis is caused by bacteria. It is a very serious illness. These germs are usually passed from one person to another through infected saliva or mucus. Most people who get bacterial meningitis get it
from one of two types of bacteria:1
- Streptococcus pneumoniae. This is a common type of bacteria that causes a number of illnesses besides meningitis, such as ear and sinus infections and pneumonia.
- Neisseria meningitidisNeisseria meningitidis. This is bacteria you can have in your throat without getting sick. But you can pass it to others, who may then get seriously ill with meningitis.
In the United States, bacterial meningitis mainly affects
Other types of bacteria that sometimes cause meningitis are:
The Centers for Disease Control and
Prevention (CDC) recommends screening for group B streptococci in all pregnant
women at 35 to 37 weeks. Women who have the bacteria are given antibiotics
during labor in order to prevent infection in their newborns.3
In rare cases, other
kinds of bacteria cause meningitis, usually in people with long-term medical
conditions. Meningitis also can be caused by
other organisms, such as a fungus, and by conditions such as cancer or lupus. Meningitis also can be a
complication of an injury (particularly to the skull or face), or