What is Meningitis?

Meningitis is a rare but serious condition caused by inflammation of the protective membranes (called meninges) that cover the brain and spinal cord. It’s usually caused by a bacterial or viral infection, especially infection with Haemophilus influenzae (HiB), pneumococcus, and enterovirus organisms, but factors like fungus, cancer, or certain medications can also cause meningitis.

Today, thanks to widespread vaccination with the HiB, pneumococcal, and meningococcal vaccines, these diseases are much less common than in the past. In fact, the Hib vaccine has eliminated more than 99 percent of cases and the pneumococcal vaccine has cut cases by more than 90 percent. Partly as a result of these reductions, according to the CDC, the number of bacterial meningitis cases dropped by almost 50 percent between 1998 and 2007, with a greater reduction among infants and children.

Meningitis is a fast-moving disease, so when it’s caught early, it can be successfully treated. But since the symptoms of the disease are similar to those of many other infections, it can be difficult to diagnose.

There are five types of meningitis:

Bacterial meningitis is often severe and can lead to serious complications. It is a true medical emergency. It can be caused by several strains of bacteria, such as Streptococcus pneumonia, Haemophilus influenza, Neisseria meningitidis and Listeria monocytogenes. Everyone is at risk of bacterial meningitis, but infants are at higher risk. The disease is spread from person to person through respiratory and throat secretions (for example, kissing). You can’t get the disease by breathing the air where an infected person has been or through casual contact.

Viral meningitis is much more common and is less severe than bacterial meningitis. It’s usually caused by enteroviruses, but can also be caused by mumps, Herpes virus, and viruses spread by mosquitoes and other bugs. These viruses tend to spread more in the late summer and early fall. The disease is usually spread by fecal contact, but it can also be spread through respiratory secretions (like mucus, spit, and saliva).  Anyone can be infected, but newborns (up to 1 month old) and people with a weakened immune system are at greater risk. Kids under the age of 5 are also at increased risk.

Fungal meningitis is pretty rare. It’s usually caused by a fungus that’s spread through the blood to the spinal cord. Anyone can get the disease, but those with a weakened immune system, like people with cancer or AIDS, are at greater risk. Unlike bacterial or viral meningitis, fungal meningitis is not spread from person to person. The disease can develop after taking medications that dampen immunity, like steroids.

Parasitic meningitis is very rare. It occurs when a parasite enters the body through the nose and travels to the brain, where it destroys brain tissue. The most common way people are infected is when they swim or dive in freshwater lakes or rivers.

Non-infectious meningitis is not spread from person to person; instead, it’s caused by certain drugs, head injury, brain surgery, or conditions like cancer and lupus.

Sources:

• Mayo Clinic
• Meningitis.
  Centers for Disease Control and Prevention
• Bacterial Meningitis.
  Nemours Foundation
• Meningitis.
  The National Meningitis Association
• Meningitis.

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