What is meningitis?
The membranes that surround your spinal cord and brain are called meninges. The definition of meningitis refers to the inflammation of these membranes. Several factors may cause meningitis, and each may manifest differently in individual patients.
The swelling caused by meningitis usually produces symptoms and signs like stiff neck, fever, and headache.
Types of meningitis
Bacterial, viral, fungal, parasitic, and non-infectious are five possible types of meningitis. In some cases, this condition can improve on its own within a few weeks. Alternatively, meningitis can be severe and require urgent antibiotic treatment to prevent death. The severity of meningitis depends on the cause of the infection. Early diagnosis and treatment of bacterial meningitis can help prevent severe complications. Therefore, it is essential to seek medical care if you notice signs or symptoms of meningitis in yourself or other people.
The most common cause of meningitis is a viral infection. Still, a bacterial infection also often results in this condition. Additionally, parasitic and fungal infections can also cause meningitis, but it rarely occurs.
The most severe types of meningitis are those caused by bacterial infections. These infections can be life-threatening, so early identification of the source of the infection is crucial.
Acute bacterial meningitis most often happens when an infection occurs somewhere in the body. The bacteria travel through the bloodstream to the spinal cord and the brain. Another possible scenario is when bacteria gain access directly to the meninges. For example, it can happen due to a fracture in the skull, a sinus or ear infection, or, in rare cases, following some surgical procedures. Several different strains of organisms can cause meningitis, the most common of which are:
- Streptococcus pneumoniae (pneumococcus): This bacterium frequently causes sinus or ear infections or pneumonia. It is the most frequent cause of bacterial meningitis in the United States, occurring in adults, young children, and infants. A vaccine is available to help reduce the risk of infection.
- Neisseria meningitidis (meningococcus): There is also a vaccine available to help reduce the risk of this infection which occurs mainly in young adults and teens, especially those residing in boarding schools, college dorms, and in other community settings. It is very contagious. The bacteria spread to the meninges from an infection in the upper respiratory system and causes meningitis.
- Haemophilus influenzae (haemophilus): There is an immunization available to prevent the occurrence of this infection, which used to be the primary cause of childhood bacterial meningitis.
- Listeria monocytogenes (listeria): Most healthy people exposed to listeria don’t become sick. Still, certain groups of people are susceptible to meningitis caused by this bacteria. These groups include people with a weakened immune system, pregnant women, older adults, and newborns. Listeria can also affect the fetus. Therefore, if a woman is infected late in her pregnancy, the baby may be stillborn or live only a short time after birth. Listeria is often found in hot dogs, lunch meats, and soft cheese.
Virus-caused meningitis usually isn’t a severe condition and often resolves on its own. In the United States, viruses belonging to a group known as enteroviruses cause viral meningitis most of the time. The cases of such meningitis most commonly occur in the later summer months and the early fall. Other viruses that can also cause viral meningitis include West Nile virus, herpes simplex virus, HIV, mumps virus, etc.
Some of the signs and symptoms of chronic meningitis mimic those of acute one: fever, headaches, vomiting, and mental fogginess. However, the development of the illness differs. Acute meningitis comes on very suddenly, and chronic meningitis develops slowly. It is due to the slow-growing infections that affect the fluid and the membranes surrounding the brain. This form of meningitis develops over two or more weeks.
One of the causes of chronic meningitis is fungal meningitis. This condition does not occur frequently, and it cannot be spread from person to person. Its symptoms are often similar to those of acute bacterial meningitis. One common type of fungal meningitis is cryptococcal meningitis. This condition usually affects people with a compromised immune system. If it is not treated with antifungal medicines, it is life-threatening. A multi-state outbreak of fungal meningitis occurred in 2012 after spinal injections with contaminated drugs were used for neck or back pain treatment.
Other causes of meningitis
Meningitis can sometimes occur for reasons unrelated to infections, including drug allergies, chemical reactions, and some types of inflammatory diseases.
Meningitis risk factors
Some factors can increase the risk of developing meningitis. They include:
- Skipping immunizations: The risk for meningitis is higher for people who have not received all of the recommended childhood or adult immunizations (vaccines).
- Age: Viral meningitis is most likely to occur in children under five years old. People under the age of 20 have more chances of getting bacterial meningitis, especially if they live with others in places like college dormitories or other community settings.
- Place of residence: People who live on military bases, children in boarding schools, or young adults in dormitories have an increased likelihood of meningococcal meningitis. This type of infection spreads via the respiratory route. Therefore, it is likely to spread among groups of people living together.
- Pregnancy: Pregnant women have a higher risk of developing listeriosis, an infection caused by listeria bacteria. This condition increases the chances of miscarriage, stillbirth, and preterm delivery. In addition, it can cause meningitis.
- Compromised immunity: When your immune system can’t fight off infection, you are at increased risk for meningitis. Conditions that may compromise your body’s immunity include diabetes, AIDS, alcoholism, and immunosuppressive medications administration. People who have had their spleen removed may also be at increased risk, as it is a vital component of the immune system.
Complications of meningitis
The longer meningitis is left without proper management, the greater the risk of adverse outcomes. Some meningitis complications can be severe, including seizures and lasting neurological damage. These complications include:
- Memory problems
- Hearing loss
- Brain damage
- Learning disabilities
- Difficulty walking
- Kidney failure
You can read about symptoms of this disease in our next article – “Symptoms. Meningitis”