Causes and types of meningitis
What causes meningitis?
Of the various types of meningitis, viral and bacterial infections are contagious and can be transmitted through close contact (such as kissing) with another person, sneezing or coughing, as well as sharing eating utensils, a toothbrush or even a cigarette. A bacterial infection can be extremely life-threatening, while viral meningitis is typically less severe.
Viral and bacterial infections are the most common cause of meningitis.
- Viral meningitis: Typically, the most common form of infection, often occurring during the summer and autumn months. The infection is classified as either coxsackievirus A, coxsackievirus B or echoviruses and typically falls into an Enterovirus category. Generally, only a small percentage of individuals with a virus in this category fall ill with meningitis. Viruses which can develop into meningitis include mumps, measles, HIV, influenza (flu), herpes simplex viruses and the West Nile virus. Viral meningitis typically clears on its own, without much treatment and doesn’t affect the brain as severely as a bacterial infection can. Most with a viral infection will be able to recover completely once the infection clears.
- Bacterial meningitis: This infection is highly contagious and can be life-threatening (it can be fatal within a matter of hours), with or without sufficient treatment. Immediate medical care is necessary for this type of infection. If not sufficiently treated, and quickly, it can also cause permanent damage to the brain, as well as other parts of the body. There are several types of bacteria which commonly cause this form of meningitis. These are Streptococcus pneumoniae (also known as pneumococcal meningitis which is generally found in the nasal cavity, sinuses and respiratory tract), Neisseria meningitides (also known as meningococcal meningitis which is easily spread through respiratory fluids, as well as saliva), Haemophilus influenza (also known as Hib, this can lead to other infections affecting the blood, windpipe, arthritis and cellulitis) and Listeria monocytogenes (a food-borne bacteria often found in unpasteurised cheeses and luncheon meats). Listeria can be dangerous for pregnant woman as the bacteria can cross the placental barrier. During the final stages of pregnancy, this infection can be fatal for a baby. Bacterial meningitis typically develops when any of these types of bacteria enter the body and gets into a person’s bloodstream. Close contact, coughing or sneezing can easily spread the infection. Once in the bloodstream an infection reaches the brain and spinal cord with ease, causing a life-threatening scenario.
Other types of meningitis include:
- Fungal meningitis: A fungal infection (cryptococcal) is rare, but typically occurs in those individuals with particularly impaired immune systems. Fungal meningitis isn’t contagious, but can lead to chronic meningitis and also mimics bacterial meningitis infections. If not treated with an antifungal medication, fungal meningitis can be life-threatening and is especially high risk for those with impaired immune systems or who regularly suffer immune deficiencies.
- Chronic meningitis: This typically develops as a result of slow-growing organisms that infect the meninges. Symptoms are typically similar to those of acute meningitis (bacterial meningitis) and tend to develop over several weeks.
Other related causes
Carcinomatous (a cancer-related inflammation of the meninges) is also a rare variation of meningitis. Chemical reactions, medication allergies and some types of inflammatory diseases (such as sarcoidosis) can result in non-infectious meningitis infections.