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What Causes Meningitis?

What Causes Meningitis?

Meningitis occurs when the meninges, the protective membranes surrounding the brain and spinal cord, get inflamed or irritated. Meningitis is an outcome of certain bacteria or viruses entering the body when our immune system is weak.

These bacteria and viruses live in the nose, throat, or the intestines, and may or may not lead to illnesses. Inflammation is caused when they spread to the spinal cord and brain’s membranes, thus causing meningitis. Symptoms like a stiff neck, headache, vomiting, disorientation, confusion, and fever similar to that of a flu usually manifest in a case of meningitis. 

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Since treating bacterial meningitis early can prevent severe problems, immediate medical care should be sought if you suspect having meningitis. The germs that cause meningitis are contagious, which means that you can spread them to or get them from another person.


What causes viral meningitis?

Viral meningitis is the most common type of meningitis and usually caused by enteroviruses. It usually causes the least serious infection and can spread through mosquito bites, infected saliva, nasal discharge, etc., contact with the latter two being common when people don’t follow healthy hygiene habits. In most cases, the illness will resolve on its own in a week’s time without any problem.

What causes chronic meningitis?

This is usually caused by fungi, Mycobacterium tuberculosis, and other slow-growing organisms. These enter the membranes and fluid surrounding the brain and develop over a week or two. The symptoms are similar to acute meningitis. The most common form of fungal meningitis is Cryptococcal meningitis. This kind of meningitis is not contagious but usually attacks people who have weak immune systems, such as those who are suffering from HIV/AIDS. Chronic meningitis can be fatal if left untreated.

What causes bacterial meningitis?

This type of meningitis is serious and three types of bacteria cause it:

  • Haemophilusinfluenzae type B
  • Neisseria meningitides - This causes meningococcal meningitis.
  • Streptococcus pneumoniae bacteria - This causes pneumococcal meningitis.

The bacteria usually enter the bloodstream and travel to the brain and spinal cord, although in some cases, they can also attack the meninges directly. This problem is contagious and can spread through air when a person sneezes or coughs. Close contact, like kissing, sharing utensils, or coming in contact with the discharge of a person suffering from meningitis, may cause the infection.

Due to the introduction of new vaccines routinely given to children, Hib is no longer the main cause of bacterial meningitis.

Since certain antibiotics can stop prevent some kinds of meningitis from being contagious, your doctor must first diagnose the type of meningitis you have.

Newborns and premature babies

Group B streptococci, a type of streptococci mostly found in the vagina, are the main cause of meningitis in newborns and premature babies in their first week of life. Meningitis in newborns may also be caused by Escherichia coli bacteria, which are found in the digestive tract. Newborns are also highly vulnerable to meningitis that takes place during epidemics and to Listeria monocytogenes. Since this bacteria can cross the placental barrier, they may also affect babies still in the uterus. Newborns and premature babies who have meningitis may have symptoms such as diarrhea, stiff neck, and vomiting, and show signs of being irritable or lethargic.

Children who are 5 years old or younger

Most of the children who get meningitis are in this age group. Children under the age of 5 years are affected mostly by Haemophilusinfluenzae type B in countries that have failed to administer the Hib vaccine. These children may experience a rash, back pain, and light sensitivity, along with other common symptoms of meningitis.                               

Older children

Meningitis in older children usually occurs as a result of Streptococcus pneumoniae and Neisseria meningitides. Teenagers and young adults are the age group usually infected by Neisseria meningitides. While these bacteria commonly cause a respiratory infection, they can result in meningococcal meningitis when they enter the bloodstream. This is a highly contagious infection and can easily cause epidemics in boarding schools, college dorms, and the like. Vaccines, however, can help prevent the infection.  


Meningitis is most common among adults around the age of 25. Individuals aged 50 and above, meanwhile, have higher chances of getting meningitis caused by Listeria monocytogenes. People who get pregnant at an older age, those who have blood cancer, and elderly individuals who do not have a good level of immunity are usually the groups that get infected.

Individuals with skull damage and implanted devices

People who have sustained recent skull damage or fractures have a high risk of developing meningitis. Injury to the skull can tear the protective layers of the brain, thus providing access for the bacteria to enter the brain either from the ear or nasal spaces and cause infections. If care is not taken, sepsis may occur and the infection can spread to the nervous system. Individuals with implanted devices in the brain and meninges also have a higher chance of infection via those devices.

Weak immune systems

Staphylococci and pseudomonas are the bacteria most likely to infect people whose immune systems are weak.

Ear infections and procedures

Mastoiditis, otitis media, and head or neck infections rarely cause meningitis. Pneumococcal meningitis is more likely to occur in children who have a cochlear implant with a positioner placed inside the ear and under the skin. Children who suffer severe hearing loss have five times more chances of getting meningitis. The infection usually spreads over a period of 2 years and has to be examined frequently.

Disorders of the immune system and anatomical defects

Bacterial meningitis may recur due to congenital or acquired anatomical defects. Skull fractures are the main anatomical defect that causes meningitis. Anatomical defects account for 59% of recurrent meningitis, while weak immune systems account for only 36%. Organisms like fungi and conditions like lupus or cancer can also cause meningitis. Brain surgery or an injury (usually in the head) can lead to meningitis, too. Also, if a person again takes a drug that has caused him or her meningitis on a previous occasion, the drug can lead to recurrent meningitis.

The spread of meningitis

The germs or bacteria that cause meningitis can be spread by:

  • Kissing
  • Sneezing or coughing
  • Sharing cutlery, toothbrushes, drinking glasses, and the like
  • Not washing hands after going to the bathroom
  • Spitting

Meningitis can occur more than once. Maintaining good personal hygiene, avoiding head injuries, maintaining a healthy lifestyle, and increasing your immunity can help prevent this condition.