What Is Meningitis?
Meningitis is an inflammation of the meninges. The meninges are the three membranes that cover the brain and spinal cord. Meningitis can occur when fluid surrounding the meninges becomes infected.
The most common causes of meningitis are viral and bacterial infections. Other causes may include:
- chemical irritation
- drug allergies
Viral and bacterial meningitis are contagious. They can be transmitted by coughing, sneezing, or close contact.
Types of Meningitis
Viral and bacterial infections are the most common causes of meningitis. There are several other forms of meningitis. Examples include cryptococcal, which is caused by a fungal infection, and carcinomatous, which is cancer-related. These types are rare.
Viral meningitis is the most common type of meningitis. Viruses in the Enterovirus category cause 85 percent of cases. These are more common during the summer and fall, and they include:
- coxsackievirus A
- coxsackievirus B
Viruses in the Enterovirus category cause about 10 to 15 million infections per year, but only a small percentage of people who get infected will develop meningitis.
Other viruses can cause meningitis. These include:
- West Nile virus
- herpes viruses
- Coltivirus, which causes Colorado tick fever
Viral meningitis typically goes away without treatment.
Bacterial meningitis is contagious and caused by infection from certain bacteria. It’s fatal if left untreated. Between 5 to 40 percent of children and 20 to 50 percent of adults with this condition die. This is true even with proper treatment.
The most common types of bacteria that cause bacterial meningitis are:
- Streptococcus pneumoniae, which is typically found in the respiratory tract, sinuses, and nasal cavity and can cause what’s called “pneumococcal meningitis”
- Neisseria meningitidis, which is spread through saliva and other respiratory fluids and causes what’s called “meningococcal meningitis”
- Haemophilus influenza, which can cause not only meningitis but infection of the blood, inflammation of the windpipe, cellulitis, and infectious arthritis
- Listeria monocytogenes, which is a foodborne bacteria
What Are the Symptoms of Meningitis?
The symptoms of viral and bacterial meningitis can be similar in the beginning. However, bacterial meningitis symptoms are usually more severe. The symptoms also vary depending on your age.
Viral Meningitis Symptoms
Viral meningitis in infants may cause:
- decreased appetite
- a fever
In adults, viral meningitis may cause:
- a fever
- stiff neck
- sensitivity to bright light
- decreased appetite
Bacterial Meningitis Symptoms
Bacterial meningitis symptoms develop suddenly. They may include:
- altered mental status
- a sensitivity to light
- a headache
- a fever
- a stiff neck
Seek immediate medical attention if you experience these symptoms. Bacterial meningitis can be deadly. There’s no way to know if you have bacterial or viral meningitis just by judging how you feel. Your doctor will need to perform tests to determine which type you have.
What Are the Complications from Meningitis?
These complications are typically associated with meningitis:
- hearing loss
- brain damage
- a subdural effusion, or a buildup of fluid between the brain and the skull
What Are the Risk Factors for Meningitis?
The following are some of the risk factors for meningitis:
People with an immune deficiency are more vulnerable to infections. This includes the infections that cause meningitis. Certain disorders and treatments can weaken your immune system. These include:
- autoimmune disorders
- organ or bone marrow transplants
Cryptococcal meningitis, which is caused by a fungus, is the most common form of meningitis in people with HIV or AIDS.
Meningitis is easily spread when people live in close quarters. Being in small spaces increase the chance of exposure. Examples of these locations include:
- college dormitories
- boarding schools
- day care centers
Pregnant women have an increased risk of listeriosis, which is an infection caused by the Listeria bacteria. Infection can spread to the unborn child.
All ages are at risk for meningitis. However, certain age groups have a higher risk. Children under the age of 5 are at increased risk of viral meningitis. Infants are at higher risk of bacterial meningitis.
Working with Animals
Farm workers and others who work with animals have an increased risk of infection with Listeria.
How Is Meningitis Diagnosed?
Diagnosing meningitis starts with a health history and physical exam. Age, dorm residence, and day care center attendance can be important clues. During the physical exam, your doctor will look for:
- a fever
- an increased heart rate
- neck stiffness
- reduced consciousness
Your doctor will also order a lumbar puncture. This test is also called a spinal tap. It allows your doctor 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. Common tests include the following:
- Blood cultures identify bacteria in the blood. Bacteria can travel from the blood to the brain. N. meningitidis and S. pneumoniae can cause both sepsis and meningitis.
- A complete blood count with differential is a general index of health. It checks the number of red and white blood cells in your blood. White blood cells fight infection. The count is usually elevated in meningitis.
- Chest X-rays can reveal the presence of pneumonia, tuberculosis, or fungal infections. Meningitis can occur after pneumonia.
- A CT scan of the head may show problems like a brain abscess or sinusitis. Bacteria can spread from the sinuses to the meninges.
How Is Meningitis Treated?
Your treatment is determined by the cause of your meningitis.
Bacterial meningitis requires immediate hospitalization. Early diagnosis and treatment will prevent brain damage and death. Bacterial meningitis is treated with intravenous antibiotics. There’s no specific antibiotic for bacterial meningitis. It depends on the bacteria involved.
Fungal meningitis is treated with antifungal 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.
How Is Meningitis Prevented?
Maintaining a healthy lifestyle, especially if you’re at increased risk, is important. This includes things like:
- getting adequate amounts of rest
- not smoking
- avoiding contact with sick people
If you’ve been in close contact with one or more people who have a bacterial meningococcal infection, your doctor can give you preventive antibiotics. This will decrease your changes of developing the disease.
Vaccinations can also protect against certain types of meningitis. Vaccines that can prevent meningitis include the following:
- Haemophilus influenzae type B (Hib) vaccine
- pneumococcal conjugate vaccine
- meningococcal vaccine
Who Should Be Vaccinated Against Meningococcal Meningitis?
These five groups are considered at risk and should get a meningitis vaccine:
- college freshmen who live in dorms and haven’t been vaccinated
- adolescents who are 11 to 12 years old
- new high school students who haven’t been vaccinated
- people traveling to countries where meningococcal disease is common
- children who are ages 2 or older and who don’t have a spleen or have a compromised immune system
Medically Reviewed by George Krucik, MD, MBA on January 12, 2016 — Written by Verneda Lights and Elizabeth Boskey, PhD