What causes meningitis?

There are many causes of meningitis. It may be caused by complications of other diseases, or it may be a minor cold infected with bacteria. Bacteria are everywhere. When people are sick, they will produce bacteria, which can be transmitted to other people through bacteria, thus causing meningitis. Meningitis can also be caused by viruses carried by animals.

Bacterial meningitis is caused by a certain bacterial infection and is divided into three types, namely Haemophilus influenzae type B, Neisseria meningitidis (diplococcus) and Streptococcus pneumoniae (pneumococcus). About 80% of meningitis in the United States is bacterial meningitis. Usually, a small number of healthy people carry these bacteria in the nose or on the body surface and do not harm the human body. It is transmitted through coughing or sneezing. Some studies have pointed out that people are most likely to be infected by bacteria when they have a cold because the inflammation of the nose makes it extremely easy for bacteria to enter the brain.

Tuberculous meningitis is a non-purulent inflammation of the meninges caused by Mycobacterium tuberculosis, accounting for about 6% of systemic tuberculosis. After the infection of Mycobacterium tuberculosis spreads through the blood, it implants under the pia mater to form tuberculous nodules. After the nodules rupture, a large number of tuberculosis bacteria enter the subarachnoid space. In recent years, the incidence and mortality of tuberculous meningitis have tended to increase. Early diagnosis and treatment can improve the efficacy and reduce the mortality rate.

Viral meningitis can be caused by several viruses, including several associated with diarrhea, one of which may be contracted by a bite from a giant vole, for example.

Cryptococcal meningitis can also be caused by fungi, the most common of which is Cryptococcus, which is found in pigeons. Healthy people are not susceptible to fungal-related meningitis, but this is not the case for those infected with HIV, the human immunodeficiency virus that causes AIDS.