|
|
|
Bacteria
Many species of bacteria can cause
meningitis, but three types account for about 80 percent of cases:
- Neisseria meningitidis (meningococcus)
Meningococcus is found in the nasopharynx of about 5 percent of the population and is
spread by respiratory droplets and close contact. For unknown reasons, only a small
fraction of carriers develop meningitis. Meningococcal meningitis occurs most often in the
first year of life, but may also occur in closed populations, such as schools.
- Hemophilus influenzae type b
Hemophilus influenzae type b accounts for most meningitis in children more than one month
old, but usually not in adults unless there is a predisposing factor such as head trauma
or a compromised immune system.
- Streptococcus pneumoniae (pneumococcus)
Pneumococcus is the most common cause of adult meningitis. Those at high risk are
alcoholics and people with chronic ear infections, sinus infections, closed head injury,
recurrent meningitis, pneumococcal pneumonia, sickle cell disease or those without a
spleen.
|
|
