What You Need to Know About Meningitis

How Meningitis Infects You

Usually, meningitis occurs when a virus or bacteria infects the brain, spinal cord, or the meninges themselves. The immune system tries to fight these infections by triggering an inflammatory response, which causes the meninges to swell and push against the brain and spinal cord.

Pressure against these organs can cause temporary symptoms, like headaches and confusion, but it can also limit blood flow to the brain and can cause long-term damage or even death.

Why Bacterial Meningitis Is So Scary

Most cases of meningitis that occur in the United States are not caused by a bacterial infection. But most of the very serious cases—those that result in death or permanent disability—are.

Between 2003 and 2007, about 500 people died every year from bacterial meningitis, according to the Centers for Disease Control and Prevention. Thousands more became very sick or developed long-term health problems.

Many types of bacteria can cause swelling around the brain and spinal cord, but some of the most common are Group B Streptococcus, Streptococcus pneumonia, Listeria monocytogenes, Escherichia coli, and Neisseria meningitidis.

These bacteria can be passed from mothers to babies during birth; between people via coughing, sneezing, kissing; or by eating contaminated food. Living in close quarters (like a college dorm or military barracks) can increase the risk of contracting bacterial meningitis because people are exposed to more bacteria.

Other Types of Meningitis: Viral and Fungal

Bacterial meningitis may be the most common type of meningitis in the United States, but it's not the most common, viral meningitis holds that record.

Most cases are actually caused by viruses, including herpes, human immunodeficiency virus (HIV), mumps, and West Nile virus. Meningitis cases caused by these and other viruses are usually mild and go away on their own—although they can still cause symptoms like fever, headache, and stiff neck.

Rarely, meningitis can develop when certain types of fungi enter the bloodstream and spread to the spinal cord and brain.

Fungal meningitis is not common in the United States, but people with weakened immune systems are at increased risk, especially for a type called cryptococcal meningitis. They may become infected if they are exposed to contaminated soil or animal droppings, and breathe in fungal spores.

Other Types of Meningitis: Parasitic and Non-infectious

Certain parasites can also cause a rare form of meningitis called eosinophilic meningitis, or EM, whose name refers to an increased level of white blood cells (called eosinophils) in the fluid around the brain and spinal cord.

Parasitic meningitis is not contagious from person to person and is usually contracted when a person eats contaminated food or accidentally ingests contaminated animal feces.

Finally, there are certain types of meningitis that aren't caused by an infection at all. Rather, they can occur when inflammation happens as a result of physical trauma—like brain surgery, or a serious blow to the head—or a chronic disease, like cancer, lupus, or rheumatoid arthritis.

Certain drugs can cause inflammation of the meninges, as well. These types of meningitis are referred to as non-infectious meningitis.

Is Meningitis Contagious?

Unfortunately, this isn't a "yes" or "no" answer—it's complicated. Some causes of meningitis are contagious and others aren't.

Bacterial meningitis, like we covered earlier, can be passed from one person to another. (Mothers can pass meningitis-causing bacteria to babies during childbirth, people can pass it to each other by kissing, and so forth.)

But other cases of meningitis, like those caused by inflammation that stems from physical trauma, aren't contagious.

Basically, you can't "catch" meningitis–since it's technically swelling around the brain and spinal cord–but exposure to bacteria that cause meningitis can put you and those around you at risk.

What Parents of Newborns Need To Know

"When small babies get meningitis in the first few weeks of life, oftentimes the only symptom is fever," says Dr. Pellett Madan. "Sometimes they have a little bit of fussiness, but in the very beginning they only have fever–and that's why anytime a baby in the first few weeks has a fever, we tell the parents to bring them in right away."

When babies this young develop meningitis, it's usually caused by bacteria in the mother's genital area that infected the baby during birth. Young babies can also catch a virus or a bacterial infection from contact with another infected individual, but these scenarios are less common.

"I usually advise parents of young babies to use common sense," says Dr. Pellett Madan. "People should wash their hands before they hold a baby, and if someone is known to be sick with a runny nose or a sore throat, that individual shouldn't be going to someone's home to visit a newborn."

Meningitis in Children and Adolescents

When toddlers and school-age children develop meningitis, it's usually caused by a virus. "Children in this age group get a fever, a stiff neck, and may have difficulty walking or reaching for their toys," says Dr. Pellett Madan. "If they're old enough to talk, they may be saying things that don't make a lot of sense."

In adolescents, early signs of meningitis closely resemble a cold or flu. "It can start with a runny nose and a sore throat, but very rapidly within hours they can develop a high fever, stiffness, and confusion," says Dr. Pellett Madan. "They may even become completely unresponsive so that you can't wake them up."

"This is also the age group where doctors begin to worry more about bacterial meningitis," says Dr. Pellett Madan—specifically, the type caused by Neisseria meningitidis. "This type of meningitis can make a child sick so quickly that sometimes there's a tremendous amount of damage done before we can even diagnose it," she says.

Teens and College Students Are at Increased Risk

Bacterial meningitis can spread quickly among people in close quarters—at school, in college dormitories, or on sports teams, for example. And the type of bacteria that has caused recent high-profile outbreaks on college campuses, Neisseria meningitides, is especially fast moving and dangerous.

"Freshmen living in dorms are at increased risk, and that's why we want kids to be vaccinated before they go off to college," says Sandra Adamson Fryhofer, MD, Internal Medicine in Atlanta and Adjunct Associate Professor of Medicine at Emory University School of Medicine.

In 2014 and 2015, the Food and Drug Administration approved vaccines that protect against meningitis B (also known as meningococcal disease), a rare but serious form of meningitis not covered by other available vaccines.

Adults Are Still at Risk of Meningitis Too

Children and young adults may be at increased risk for meningitis, but people of any age can be affected. In adults, bacterial meningitis can be caused by streptococcus pneumoniae, the same bacteria that causes pneumonia and sinus infections.

Older adults, pregnant women, and people with weakened immune systems are also at increased risk of developing meningitis from listeria, a type of bacteria found in certain cheeses, cold cuts, and processed meats.

And while Neisseria meningitides aren't common among adults in the United States, it is prevalent in other parts of the world, including sub-Saharan Africa. People of all ages planning to travel to this area should talk with their doctors about getting vaccinated before they go.

How Meningitis Is Diagnosed

If a doctor suspects meningitis, they may order an X-ray or computed tomography (CT) scan to look for signs of inflammation around the brain and spinal cord. Blood tests may also be used to identify bacteria or other microorganisms that might be responsible for the infection.

A definitive diagnosis of meningitis, however, requires a spinal tap: a procedure in which a doctor inserts a needle into a patient's back and collects a sample of cerebrospinal fluid. The levels of glucose, protein, and white blood cells in this fluid can indicate how much inflammation is present.

"It can also help doctors determine the cause of meningitis," says Dr. Fryhofer, "whether it's bacterial, viral, or something else."

Medication and Treatment for Meningitis

Bacterial meningitis is treated with antibiotics, and receiving appropriate treatment can reduce the risk of dying to below 15 percent, according to the National Institutes of Health. People who are exposed to bacterial meningitis may also be given antibiotics as a precaution, even if they don't show signs of being sick.

Antibiotics won't work for meningitis not caused by bacteria.

Fungal meningitis can be treated with anti-fungal medications, usually given via IV in the hospital.

Treatment for viral and parasitic meningitis is trickier: There are no medications that target the source of these infections, so treatment is mostly focused on addressing symptoms like pain and fever.

Why Vaccines Are So Important

Because meningitis can be difficult to identify and diagnose in a timely manner, vaccinating against the disease is extremely important.

"It can be very hard for a parent to know when a child is at the threshold of having a cold or something more serious, and that's why we want to prevent getting to that point in the first place," says Dr. Pellett Madan.

Children should receive a meningococcal conjugate vaccine at age 11 or 12, and a booster shot at age 16, to protect against four types of bacteria (serogroups A, C, W, and Y) that cause meningitis.

Teenagers heading off to college may also choose to receive another shot, called the Serogroup B meningococcal vaccine, to protect specifically against meningitis B.

Even though adults can be hit hard by each type of meningitis, vaccines aren't recommended—unless an adult is at a higher risk due to pregnancy or a weakened immune system, for example.

Other routine vaccinations can protect babies against other bacteria that can cause meningitis, as well. "We used to see a lot of meningitis in kids from bacteria like streptococcus pneumonia, which we now vaccinate against," says Dr. Pellett Madan.

But there's an important caveat, she adds: "The vaccines only work if you give them on time and according to schedule."