Meningitis

E.P. Ben-Joseph

Meningitis is an inflammation of the meninges, the membranes that cover the brain and spinal cord. The inflammation is usually caused by bacteria or viruses (viral meningitis is also called aseptic meningitis). Less common causes include fungi, protozoa, and other parasites. Sometimes certain medications, cancers, or other diseases can inflame the meninges, although
such noninfectious cases of meningitis are much rarer.
Many of the bacteria or viruses that can cause meningitis are fairly common and are more often associated with other everyday illnesses. Sometimes, however, they spread to the meninges from an infection in another part of the body. The infection can start anywhere, including in the skin, gastrointestinal tract, or urinary system, but the most common source is the respiratory tract. From there the microorganisms can enter the bloodstream, travel through the body, and enter the central nervous system. In some cases of bacterial meningitis, the bacteria spread directly to the meninges from a severe nearby infection, such as a serious ear infection (otitis media) or nasal sinus infection (sinusitis). Bacteria may also enter the central nervous system after severe head trauma or head surgery.
Bacterial meningitis is less common than viral meningitis but is usually much more serious and can be life-threatening if not treated promptly. Many different types of bacteria can cause meningitis: Group B Streptococcus, Escherichia coli, Mycobacterium tuberculosis and Listeria monocytogenes are the most common causes of meningitis. Streptococcus pneumoniae (pneumococcus) and Neisseria meningitidis (meningococcus) are more frequent in children. Before the 1990s, Haemophilus influenzae type b (Hib) was the leading cause of meningitis in children. But the widespread use of the Hib vaccine as a routine childhood immunization has dramatically decreased the frequency of meningitis caused by Hib.
Viral meningitis is relatively common and far less serious than bacterial meningitis. It often remains undiagnosed because its symptoms are similar to those of the common flu. The frequency of viral meningitis increases slightly in the summer and fall months because people are more often exposed to common viral agents during those seasons. Most cases of viral meningitis are associated with enteroviruses - viruses that typically cause stomach "flu." However, many other types of viruses, such as the herpes virus, can also cause meningitis. The mumps virus was once a common cause of viral meningitis, but it is now rare due to the routine use of the measles, mumps, and rubella (MMR) vaccine.
Bacterial meningitis occurs in people of all ages but is more common in the very young (infants and young children) and the elderly (people above age 60). Teenagers and college students are also slightly more at risk for the disease because of time spent in close contact with many of their peers. Viral meningitis occurs in people of all ages, although it is more common in
children.
People with less competent immune systems, such as the very young or those whose immune systems have been compromised by disease, are more at risk for all types of meningitis. Some types are more common in child-care centers, boarding schools, dormitories, and military bases, mainly because infectious diseases tend to spread quickly among large groups of people. Not receiving routine vaccines for certain infectious agents that can cause meningitis - including those for mumps, Hib, and pneumococcus - also increases a person's risk for the disease.
The long-term outlook for people who develop meningitis varies greatly and depends on age, the microorganism causing the infection, any other complications, and the treatment receives. The complications of bacterial meningitis can be severe and include neurological problems such as hearing loss, visual impairment, seizures, and learning disabilities. The heart, kidneys, and adrenal glands may also be affected. Although some people develop long-lasting neurological problems from bacterial meningitis, most who receive prompt diagnosis and treatment recover fully. The majority of cases of viral meningitis resolve with no complications.

Signs and Symptoms
The symptoms of meningitis vary and depend both on the age and on which bacterium or virus is causing the infection. The symptoms of viral meningitis are usually milder than those of bacterial meningitis. However, symptoms of bacterial and viral cases can be similar, particularly in the early stages of the disease. This makes prompt, accurate identification of the infectious organism crucial to effective treatment and the patient's recovery.
The first symptoms of meningitis may surface several days after had a cold and runny nose, diarrhea and vomiting, or other signs of a bacterial or viral infection. Some of the more common symptoms of meningitis include fever, lethargy (decreased consciousness) , or irritability. Older people may complain of a headache, photophobia (eye sensitivity to light), and a stiff neck, which is often noted by the doctor during a physical exam. Meningitis also can lead to skin rashes, although rashes caused by bacterial meningitis look different from those caused by viral meningitis. Seizures occasionally accompany meningitis as well.
Newborns and infants with meningitis may lack the classical signs described above and simply be extremely irritable or lethargic. Normally, infants who are not feeling well will be comforted when their mothers pick them up. However, a baby who has meningitis may display something called paradoxical irritability - when picking up and rocking makes more distressed. This can
be a sign of irritated meninges.
Other symptoms of meningitis in infants can include: jaundice (a yellowish tint to the skin), a stiffness of the body and neck (neck rigidity), a mild fever, a lower-than-normal temperature, poor feeding, a weak suck, and a high-pitched cry. Parents may also notice bulging fontanelles on their baby's head. (Fontanelles are the soft spot at the top/front of the baby's skull, where the bones of the skull join and are still open at that age.)

Contagiousness
Most cases of meningitis result from infections that are contagious. The infectious agents usually spread from person to person in tiny drops of fluid from the throat and nose of someone who is infected. (This could be a person with either meningitis or, more likely, the common infection caused by that germ.) The drops may become airborne when the person coughs, laughs, talks, or sneezes. They then can infect others when people breathe them in or touch the drops and then touch their own noses or mouths. Sharing food, drinking glasses, eating utensils, tissues, or towels may all transmit the infections as well. Some infectious organisms can spread through a person's stool, and someone who comes in contact with the stool - such as in day care - may contract the infection.
The infections most often spread between people who are in close contact, such as those who live together or people who are exposed by kissing or sharing eating utensils. Casual contact at school or work with someone who has one of these infections usually will not transmit the infectious agent.
It is important to remember that just because someone becomes infected with a particular bacterium or virus does not automatically mean that person will get meningitis. In most cases, the microorganism will simply cause a run-of-the-mill respiratory or gastrointestinal infection. In some instances, people may carry one of the germs that can cause meningitis without becoming ill at all. Even though they have no symptoms of disease, they can still spread the germ, however. Patients with meningitis typically remain contagious while they still have symptoms. People who have bacterial meningitis can be contagious for about 24 hours after they begin taking antibiotics.

Prevention
Routine immunization of young adolescents will help prevent this rare but serious infection. Experts now recommend that kids who are 11 years old get vaccinated for meningococcal disease, a serious bacterial infection that can lead to meningitis. The vaccine is called quadrivalent meningococcal vaccine, or MCV4. People who have not had the vaccine and are 15 years old, or entering high school should also get the vaccine. People who are entering college, and will be living in a dormitory setting should also get the vaccine.
Many of the bacteria and viruses that are responsible for meningitis are fairly common. Good hygiene is an important means of preventing any infection. Encourage your family members to wash their hands thoroughly and often, particularly before eating and after using the bathroom. Avoiding close contact with someone who is obviously ill and not sharing food, drinks, or eating utensils can help halt the spread of germs as well.
In certain cases of meningitis, doctors may decide to give antibiotics to anyone who has been in close contact with the person who is ill to help prevent additional cases of illness.
The vaccines against Hib, measles, mumps, rubella, polio, and pneumococcus can protect against meningitis caused by these microorganisms. Some high-risk people should also be immunized against certain types of meningococcus. Because bacterial meningitis is most likely to occur in
confined settings such as college dorms, some colleges ask that incoming students be vaccinated against meningococcus. This vaccine may also be recommended for people who are traveling to countries where meningitis is more common.

Incubation
This varies with the organism causing the meningitis. The incubation periods for the most common causes of meningitis range from 2 days to 2 weeks.

Duration
Even with proper treatment, bacterial meningitis may take days (and sometimes weeks) to resolve, and recovery from its effects may take even longer. Most cases of viral meningitis resolve completely within 1 to 2 weeks.

Professional Treatment
Any people with possible meningitis needs aggressive diagnosis and treatment. First the doctor will take a history and perform a physical examination. If meningitis is suspected, the doctor will order laboratory tests to help make the diagnosis. The tests will likely include a lumbar puncture (spinal tap) to collect a sample of spinal fluid. This sample will be examined for signs of inflammation and cultured for the organism that may be causing the infection.
It is crucial to fight cases of bacterial meningitis quickly. If a person is diagnosed with (or strongly suspected to have) bacterial meningitis, doctors will start intravenous antibiotics as soon as possible, often before the exact microorganism causing the infection has been pinpointed. Once the infectious agent is identified through laboratory tests, the antibiotics can
be changed, if necessary, or discontinued if the patient turns out to have viral meningitis.
If a person is diagnosed with bacterial meningitis, he or she will be hospitalized and closely monitored. While in the hospital, he/she will continue to receive antibiotics and may require intensive-care treatment.
He/she will receive fluids to replace those lost to fever, sweating, vomiting, and poor appetite, and may be given corticosteroids to help reduce inflammation of the meninges, depending on the cause of the disease. Complications of bacterial meningitis may require specific treatment. For
example, anticonvulsants can be given for seizures. If he/she develops shock or low blood pressure, additional intravenous fluids and certain medications may be given to increase blood pressure. Some people may need supplemental oxygen or mechanical ventilation if they have difficulty breathing. A person who has viral meningitis may also be hospitalized, although some
people are allowed to recover at home if they do not seem to be too ill.
With the exception of medication for the herpes simplex virus, there are no medications to fight the agents that cause viral meningitis, so treatment is usually aimed at relieving the symptoms. This includes rest, fluids, and over-the-counter pain medication.
Some patients who have had meningitis may require longer-term follow-up. One of the most common problems resulting from bacterial meningitis is impaired hearing, and people who have had bacterial meningitis should have a hearing test following their recovery.

Home Treatment
Any people with suspected meningitis should be seen by a doctor. Once a diagnosis has been made, all patients with bacterial meningitis and many with viral meningitis will be treated in the hospital. Older people whose laboratory tests show no signs of bacterial meningitis and who have milder symptoms may be sent home to recover. There they should get plenty of rest and drink lots of fluids. If necessary, paracetamol or ibuprofen can be used to relieve fever and headache.
People who recover at home need to be closely watched by their parents and followed by their doctors. If the condition of a person recuperating at home worsens, he/she should go to the emergency department right away.

When to Call Your Doctor
Seek medical attention immediately if you suspect meningitis or if he/she exhibits symptoms such as vomiting, headache, lethargy or confusion, neck stiffness, rash, and fever. Infants who have fever, irritability, poor feeding, and lethargy should be assessed by a doctor right away.
If he/she has had contact with someone who has meningitis (for example, in a child-care center or a college dorm), call doctor to determine whether your child should take preventive medication.
(AAFP)