What is meningitis?
An inflammation of the membranes and fluids that cover the spinal cord and brain is known as Meningitis. According to statistics, over 1 million people every year get affected by different types of meningitis. The most common cause of meningitis is the infection, and this infection can be caused by different kinds of germs like parasites, viruses, fungi, and bacteria.

What are the different types of meningitis?
Bacterial meningitis
Bacterial meningitis is an aggressive type of meningitis that can develop quickly – often within a few hours. Bacterial meningitis is so dangerous that it leads to death or permanent disability within a few hours.

In 10-20% of the cases, bacterial meningitis is fatal, accounting for about 170,000 deaths around the world every year. Most of these deaths occur within 24-48 hours of the onset of the symptoms.

Streptococcus pneumoniae (the pneumococcus), Neisseria meningitidis (the meningococcus) and Haemophilus Influenzae Type B (Hib) are the main causes of bacterial meningitis. These bacteria are divided into groups of three that are known as serotypes or serogroups. To state an example, 95% of meningococcal meningitis and septicemia cases are caused by meningococcus serogroups A, B, C, W, and Y.

Septicaemia, also known as blood poisoning, is a potentially life-threatening infection that is caused when meningitis-causing bacteria gets into the bloodstream. The infection can occur on its own or in addition to meningitis.

It is very common to find meningitis bacteria in the throat and nose area in people. The bacteria that live in these areas of the human body usually cause no harm and help build immunity against infections. In case the bacteria invade the body, in a rare case, the disease manifests itself.

Through respiratory droplets released through coughing, sneezing and making close contact, the bacteria becomes contagious as it can spread from person to person.

Group B Streptococcus, which is a common cause of neonatal meningitis,  Escherichia coli and Mycobacteria tuberculosis (TB) are other bacteria that can cause meningitis. There are various vaccines available to treat the different types of bacterial meningitis.

Viral meningitis
A little less severe as compared to bacterial meningitis, viral meningitis is one of the common types of meningitis observed in patients. Although full recovery for many people takes months or weeks, most patients manage to recover from the disease without any permanent damage.

Respiratory droplets that are released through coughing, kissing and sneezing or by fecal contamination contain viruses that cause meningitis. Enterovirus is a common group of viruses that live in the intestinal and respiratory tract and are responsible for causing sore throats, colds, headaches, muscle aches and soreness and fevers. Enteroviruses often manage to spread to the meninges and cause meningitis.
In developing nations, the mumps virus can also cause meningitis. In countries that have high rates of MMR immunization, this is rare as the combined measles-mumps-rubella vaccine (MMR) works well against the virus. Good hygiene usually helps prevent the spread of this virus although there are many types of viral meningitis for which vaccines are not available.

Fungal meningitis
Fungal meningitis occurs infrequently but can be severe. It is not contagious and usually spreads through the inhalation of fungal spores from the environment. People with impaired immune systems are more prone to this, including people who have AIDS. There are no vaccines that protect against fungal meningitis.

Parasitic meningitis is usually is caused by parasites found in contaminated soil, food, and water, and is more common in underdeveloped nations.

As a complication related to another illness like syphilis, mumps, and tuberculosis, noninfectious meningitis may also develop. Caused by head injury, congenital disability, and brain surgery, a break in the skin and/or bones in the face or skull makes room for the bacteria to enter the body.

In rare cases, exposure to certain medicines can also cause meningitis. Some of these medicines include:

• Mumps and rubella vaccines
• Levamisole (Ergamisol)
• Nonsteroidal anti-inflammatory medicines (e.g. diclofenac, ibuprofen, naproxen)
• Immune globulin
• Metronidazole (Flagyl)

Chemical meningitis
Disease caused by certain chemicals and substances and not infectious agents like bacteria or viruses is known as chemical meningitis. Contrast agents used during scans or X rays and certain medicines used to treat cancer and certain other drugs can cause chemical meningitis. Chemical meningitis can also be caused by fat droplets that leak into the space between the skull and brain due to rupture of benign tumors. Chemical meningitis is characterized by the absence of bacteria or other organisms in the cerebrospinal fluid and is known to be ‘sterile.’

Carcinomatous meningitis or malignant meningitis
Malignant or carcinomatous meningitis is a type of meningitis that is caused by cancer. This is one of the rare types of meningitis. It affects less than 5% of cancer patients with advanced tumors and can develop when cancer spreads to the central nervous system. Successful treatment of cancer through chemotherapy helps malignant meningitis resolve completely.