Meningitis is an inflammation of the meninges. This is the membrane that covers the brain and spinal cord. Meningitis may occur when fluid surrounding the meninges becomes infected.
The most common causes of meningitis are viral and bacterial infections. Meningitis is contagious. It can be transmitted by coughing, sneezing, or close contact. Other causes include:
- chemical irritation
- drug allergies
Bacterial meningitis is a medical emergency. It can be fatal.
The most common causes of meningitis are viruses and bacteria.
Aseptic (Viral) Meningitis
Viral meningitis usually occurs in children under the age of five. It is most common during the early fall. Thirty percent of cases are caused by enteroviruses. These viruses normally cause intestinal illnesses. West Nile virus, and influenza can also cause meningitis.
Viral meningitis is more common in adults under the age of 30 than in older adults. Outcomes are usually better than bacterial meningitis. It can resolve on its own.
Bacterial meningitis is contagious. It can also be life-threatening. Up to 40 percent of children and half of adults with this condition die. This is true even with proper treatment. The types of bacterial meningitis are:
- gram negative
There are several other types of meningitis. Cryptococcal is caused by a type of yeast. Carcinomatous is cancer-related.
Symptoms of meningitis vary by age.
Teens and young adults may have:
- stiff neck
- be irritable
- refuse to eat
- cry when being held
- have bulging fontanelles (soft spots on the top of the head)
Young children may:
- have trouble breathing
Older adults may have:
- a slight headache
Meningitis can also cause a change in mental status and sensitivity to light.
Seek immediate medical attention if you experience these symptoms. Bacterial meningitis can be deadly. There is no way to know if you have bacterial or viral meningitis by how you feel.
There are several risk factors for meningitis.
People with immune deficiency are more vulnerable to infections. This includes those that cause meningitis. People with HIV/AIDS can get pneumocystic meningitis. It is unusual in the general population.
Meningitis is easily spread when people live in close quarters. Small spaces increase the chance of exposure. Some high risk locations include:
- college dormitories
- boarding schools
- day care centers
Pregnant women have an increased risk of listeriosis. This form of meningitis is caused by listeria bacteria. Infection can spread to the unborn child.
The average age for bacterial meningitis is 25 years. Viral meningitis is most frequently seen in children under the age of five.
Working with Animals
Farm workers and others who work with animals have increased risk of infection with listeria.
Diagnosing meningitis starts with a health history and physical exam. Age, dorm residence, and day care center attendance can serve as important clues. A physical exam may show:
- increased heart rate
- neck stiffness
- reduced consciousness
Meningitis is usually diagnosed with a lumbar puncture. This test is also called a spinal tap. It allows doctors to look for increased pressure in the central nervous system. It can also find inflammation or bacteria in the spinal fluid. This test can also help determine the best antibiotic for treatment.
Other tests may also be ordered to diagnose meningitis.
CBC with Differential is a general index of health. It checks the number of red and white blood cells. White blood cells fight infection. The count is usually elevated in meningitis.
Blood cultures look for bacteria in the blood. Bacteria can travel from the blood to the brain. Meningococcus and pneumococcus can cause both sepsis and meningitis.
Chest x-rays can reveal the presence of pneumonia, TB, or fungal infections. Meningitis can occur after pneumonia.
A CT scan of the head can show problems like brain abscess or sinusitis. Bacteria can spread from the sinuses to the meninges.
Treatment is determined by the cause of meningitis.
Bacterial meningitis requires immediate hospitalization. Treatment will be with intravenous antibiotics. Early diagnosis and treatment are important. They help prevent brain damage and death. There is no specific antibiotic for meningitis. It depends on the bacteria involved.
Fungal meningitis is treated with anti-fungal agents.
Viral meningitis isn’t treated. It usually resolves on its own. Symptoms should go away within two weeks. There are no serious long-term problems associated with viral meningitis.
The following complications are associated with meningitis:
- hearing loss
- brain damage
- hydrocephalus (water on the brain)
- subdural effusion (buildup of fluid between the brain and the skull)
Preventive antibiotics are given to close contacts of people with meningococcal infection.
Vaccinations can also protect against certain types of meningitis. Vaccines that can prevent meningitis include:
- HiB vaccine (Haemophilus vaccine)
- Pneumococcal conjugate vaccine
- Meningococcal vaccine
Who Should Be Vaccinated Against Meningococcal Meningitis?
The following groups should get a meningitis vaccine:
- college freshmen who live in dorms and haven’t been vaccinated
- adolescents aged 11 to 12
- new high school students who haven’t been vaccinated
- those traveling to countries where meningococcal disease is common
- children age two or older who don’t have a spleen or are immunocompromised
Written by: Verneda Lights and Elizabeth Boskey, PhD
Published on Aug 16, 2012
Medically reviewed by George Krucik, MD