Bacterial Meningitis

More than two-thirds of all people who get bacterial meningitis are under age five, and before 1992 most of them would have been infected with Haemophilus influenzae type B (Hib). This illness has nothing to do with influenza, however, despite the name of the bacterium. Because of an effective vaccine, HIB meningitis has practically disappeared among young children in the United States.

The dread of bacterial meningitis, no matter which bacterium is responsible, is not just on its reputation as a killer but also on the real possibility of lingering neurological complications. These lingering deficits, which occur in between 20 percent and 30 percent of those surviving bacterial meningitis, can be especially devastating in infants and children. The deficits can include persistent hearing loss, mental retardation, and recurrent convulsions.

Cause Today the most common causes of bacterial meningitis are pneumococcal meningitis caused by Streptococcus pneumoniae, meningococcal meningitis caused by Neisseria meningitidis, and Listeria in babies two months of age and younger.

Meningococcal meningitis affects about 3,000 Americans a year; about half are younger than two, and two-thirds are younger than 20. The highest-risk populations are babies between four months and 12 months of age, and young adults living together in close proximity (such as in a college dormitory). Patients can become infected by inhaling the bacteria, but most patients develop only very mild upper respiratory symptoms. More serious cases occur when the bacteria enter the bloodstream. Up to 30 percent of healthy people have this bacteria in their throats without having symptoms. In North America this type of meningitis usually occurs in isolated cases, usually in February and March (and least often in September).

Pneumococcal meningitis is the second most common type of bacterial meningitis, which kills one out of every five people who contract it. Children under age two are among the most easily infected. This type of meningitis occurs sporadically during the cold and flu season but not in epidemics. This bacteria is also responsible for ear infection, pneumonia, and sinusitis. There are more than 80 types of N. meningitidis.

Symptoms Classic signs of meningitis include sudden high fever (between 100°F and 106°F), with chills, vomiting, stiff neck, seizures, and intense headache in the front of the head. The neck will hurt if the child tries to touch the chin to the chest. There may be muscle spasms or leg pains, and bright lights may irritate the eyes.

All types of bacterial meningitis can appear suddenly or gradually in children. The less-common gradual type is harder to diagnose because symptoms are similar to other mild childhood illnesses: cold symptoms, fever, lethargy, vomiting, appetite loss. A sudden attack is easier to diagnose, although it may indicate a more serious case.

Abnormal behavior also may announce the onset of meningitis, including aggressiveness, irri tability, agitation, delirium, or screaming. This is followed by lethargy and stupor or coma.

Babies between the ages of three months and two years may have fever, vomiting, irritability, seizures, and a high-pitched cry. The baby may become rigid, and the soft spot on the front of the baby's head may bulge.

Sometimes the illness may be preceded by a cold or an ear infection. Any sudden change in consciousness or any unusual behavior in a young child may be a sign of meningitis.

Diagnosis A spinal tap must be done to diagnose meningitis. The normally clear fluid is analyzed for the presence of bacteria and other evidence of infection. Bacteria will grow in the fluid within 48 hours; rapid tests on urine or blood can give results in a few hours and are most helpful in determining what type of bacteria are causing the infection. However, since the disease can progress so quickly, treatment with intravenous antibiotics is usually started even before test results are available.

Treatment Without treatment, most children would die from meningitis; with antibiotics, 95 percent recover. Current antibiotics used to treat bacterial meningitis include cephalosporins (especially cefotaxime and ceftriaxone) and various types of penicillin. At least one week of treatment is required.

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