Meningitis Health Article

Definition

Meningitis is a serious inflammation of the meninges, the membranes (lining) that surround the brain and spinal cord. It can be of bacterial, viral, or fungal origin.

Description

Meningitis is usually the result of a viral or bacterial infection. Viral meningitis, also called aseptic meningitis, is generally less severe and often disappears without specific treatment, while bacterial meningitis can be quite serious and may result in brain damage, hearing loss, or learning disabilities in children. The infection may even cause death.

Bacterial meningitis is either monococcal or pneumococcal, depending on the type of bacteria responsible for the infection. Meningitis caused by Haemophilus influenzae and related strains (A, B C, Y, and W135) is also called meningococcal meningitis. Similarly, meningitis due to Streptococcus pneumoniae is also called pneumococcal meningitis.

Transmission

Most types of meningitis are contagious. A person may be exposed to meningitis bacteria when someone with meningitis coughs or sneezes. The bacteria can also spread through kissing or sharing eating utensils or a toothbrush.

Demographics

According to the National Institute of Neurological Disorders and Stroke (NINDS), some 6,000 cases of pneumococcal meningitis are reported in the United States each year. Meningococcal meningitis is common in minors ages two to 18. Each year about 2,600 people get this highly contagious disease. High-risk groups include infants under the age of one year, people with suppressed immune systems, travelers to foreign countries where the disease is endemic, and college students and Army recruits who reside in dormitories and other close quarters. Between 10 and 15 percent of cases are fatal, with another 10 to 15 percent involving brain damage and other serious side effects.

Causes and symptoms

The bacteria which cause bacterial meningitis live in the back of the nose and throat region and are carried by 10 to 25 percent of the population. They cause meningitis when they get into the bloodstream and travel to the meninges.

At least 50 kinds of bacteria can cause bacterial meningitis. According to the Centers for Disease Control (CDC), before the 1990s, Haemophilus influenzae type b (Hib) was the leading cause of bacterial meningitis, but subsequent vaccines given to all children as part of their routine immunizations have reduced the occurrence of the disease due to H. influenzae. As of 2004, Streptococcus pneumoniae and Neisseria meningitidis were the leading causes of bacterial meningitis.

In newborns, the most common agents of meningitis are those that are contracted from the newborn's mother, including Group B streptococci (becoming an increasingly common infecting organism in the newborn period), Escherichia coli, and Listeria monocytogenes. The highest incidence of meningitis occurs in babies less than a month old, with an increased risk of meningitis continuing through about two years of age.

Older children are more frequently infected by the bacteria Haemophilus influenzae, Neisseria meningitidis, and Streptococci pneumoniae.

Most cases of viral meningitis are caused by enteroviruses (viruses that typically cause stomach flu). However, many other types of viruses, such as the herpes simplex virus, the mumps and measles viruses (against which most children are protected due to mass immunization programs), the virus that causes chickenpox, the rabies virus, and a number of viruses that are acquired through the bites of infected mosquitoes.

Meningitis symptoms include high fever, headache, and stiff neck in children over the age of two years. These symptoms can develop over several hours, or they may take one to two days. Other symptoms may include nausea, vomiting, discomfort looking into bright lights, confusion, and sleepiness. In some cases, a rash may be present. In newborns and small infants, these symptoms may be absent or difficult to detect, and the infant may only appear slow or inactive, or be irritable, have vomiting, or be feeding poorly. As the disease progresses, patients of any age may also have seizures.

When to call the doctor

Parents should call a doctor if a child has a temperature above 101°F (38.5°C). If any meningitis symptoms occur, the child should see a doctor immediately, as early diagnosis and treatment are very important for a successful outcome.

Diagnosis

Viral meningitis often remains undiagnosed because its symptoms are similar to those of the common flu. As for bacterial meningitis, the diagnosis is established by growing bacteria from a sample of spinal fluid. The spinal fluid is obtained by performing a lumbar puncture (also called a spinal tap), in which a needle is inserted into an area in the lower back where fluid in the spinal canal is readily accessible.