What is bacterial
meningitis?
Meningitis is an infection
of the fluid in the spinal cord and the fluid that surrounds the
brain. Meningitis is usually caused by an infection with a virus
or a bacterium. Knowing whether meningitis is caused by a virus or
a bacterium is important because of differences in the seriousness
of the illness and the treatment needed.
VIRAL MENINGITIS is usually relatively mild. It
clears up within a week or two without specific treatment. Viral
meningitis is also called aseptic meningitis.
BACTERIAL MENINGITIS is much more serious. It
can cause severe disease that can result in brain damage and even
death.
What
bacteria cause bacterial meningitis?
Bacterial meningitis is most commonly caused by
one of three types of bacteria: Haemophilus influenzae type
b (Hib), Neisseria meningitidis, and Streptococcus
pneumoniae.
New vaccines being given to
children as part of their routine immunizations have reduced the
occurrence of serious Hib disease. Today, Neisseria
meningitidis and Streptococcus pneumoniae are the
leading causes of bacterial meningitis. Meningitis caused by
Neisseria meningitidis is also called MENINGOCOCCAL
MENINGITIS. Meningitis caused by Streptococcus pneumoniae
is called PNEUMOCOCCAL MENINGITIS.
It is important to know which
type of bacteria is causing the bacterial meningitis because
antibiotics can prevent some types from spreading and infecting
other people.
Where is bacterial meningitis found?
Bacterial meningitis is found worldwide. The bacteria often live
harmlessly in a person's mouth and throat. In rare instances,
however, they can break through the body's immune defenses and
travel to the fluid surrounding the brain and spinal cord. There
they begin to multiply quickly. Soon, the thin membrane that
covers the brain and spinal cord (meninges) becomes swollen and
inflamed, leading to the classic symptoms of meningitis.
How do people get bacterial meningitis?
The bacteria are spread by direct close contact with the
discharges from the nose or throat of an infected person.
Fortunately, none of the bacteria that cause meningitis are very
contagious, and they are not spread by casual contact or by simply
breathing the air where a person with meningitis has been.
What are the signs and symptoms of bacterial meningitis?
In persons over age 2, common symptoms are high fever, headache,
and stiff neck. These symptoms can develop over several hours, or
they may take 1 to 2 days. Other symptoms can include nausea,
vomiting, sensitivity to light, confusion, and sleepiness. In
advanced disease, bruises develop under the skin and spread
quickly.
In newborns and infants, the
typical symptoms of fever, headache, and neck stiffness may be
hard to detect. Other signs in babies might be inactivity,
irritability, vomiting, and poor feeding.
As the disease progresses,
patients of any age can have seizures.
Who is at risk for bacterial meningitis?
Anyone can get bacterial meningitis, but it is most common in
infants and children. People who have had close or prolonged
contact with a patient with meningitis caused by Neisseria
meningitidis or Hib can also be at increased risk. This includes
people in the same household or day-care center, or anyone with
direct contact with discharges from a meningitis patient's mouth
or nose.
How is bacterial meningitis diagnosed?
The diagnosis is usually made by growing bacteria from a sample of
spinal fluid. The spinal fluid is obtained by a spinal tap. A
doctor inserts a needle into the lower back and removes some fluid
from the spinal canal. Identification of the type of bacteria
responsible for the meningitis is important for the selection of
correct antibiotic treatment.
What complications can result from bacterial meningitis?
Advanced bacterial meningitis can lead to brain damage, coma, and
death. Survivors can suffer long-term complications, including
hearing loss, mental retardation, paralysis, and seizures.
What is the treatment for bacterial meningitis?
Early diagnosis and treatment are very important. If symptoms
occur, the patient should see a doctor right away. Bacterial
meningitis can be treated with a number of effective antibiotics.
It is important, however, that treatment be started early.
How can bacterial meningitis be prevented?
-
Vaccines -- There are vaccines
against Hib, some strains of Neisseria meningitidis, and many
types of Streptococcus pneumoniae.
The vaccines against Hib are
very safe and highly effective. By age 6 months of age, every
infant should receive at least three doses of an Hib vaccine. A
fourth dose (booster) should be given to children between 12 and
18 months of age.
The vaccine against
Neisseria meningitidis (meningococcal vaccine) is not
routinely used in civilians in the United States and is
relatively ineffective in children under age 2 years. The
vaccine is sometimes used to control outbreaks of some types of
meningococcal meningitis in the United States. New meningococcal
vaccines are under development.
The vaccine against
Streptococcal pneumoniae (pneumococcal vaccine) is not
effective in persons under age 2 years but is recommended for
all persons over age 65 and younger persons with certain medical
problems. New pneumococcal vaccines are under development.
-
Disease reporting -- Cases of
bacterial meningitis should be reported to state or local health
authorities so that they can follow and treat close contacts of
patients and recognize outbreaks.
-
Treatment of close contacts --
People who are identified as close contacts of a person with
meningitis caused by Neisseria meningitidis can be given
antibiotics to prevent them from getting the disease.
Antibiotics for contacts of a person with Hib disease are no
longer recommended if all contacts 4 years of age or younger are
fully vaccinated.
- Travel precautions -- Although large
epidemics of bacterial meningitis do not occur in the United
States, some countries experience large, periodic epidemics of
meningococcal disease. Overseas travelers should check to see if
meningococcal vaccine is recommended for their destination.
Travelers should receive the vaccine at least 1 week before
departure, if possible.
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