Meningitis: Viral, Bacterial and Fungal

     There is confusion about the different forms of meningitis. Any time “itis “ is added onto the end of a medical word, it indicates infection or inflammation. If your appendix is inflamed, you have “appendicitis”. If your tonsils are infected, you have “tonsillitis”. The meninges are layers of tissue that cover and hold in the fluid that surrounds the brain and spinal cord. Meningitis is an infection of these coverings. 

     The three most common organisms that cause infection in human beings are viruses, bacteria and funguses. Viruses are very small and cause infections like colds, chicken pox and influenza. There are only a small number of antiviral drugs that can treat these infections. Bacteria are larger and cause staph skin infections and strep throat and other infections that are treated with antibiotics. Funguses are larger still and cause yeast and fungal skin infections such as athlete’s foot. These are treated with antifungal drugs. Any of these three organisms can cause meningitis, but they do it in different ways.

     Viral infections of the brain and surrounding tissues are often referred to as encephalitis because they can affect the entire brain (“encephalo” refers to the brain). These viral infections can be mild or severe and are caused by viruses such as West Nile virus and equine encephalitis virus. They are injected into humans by mosquito bites.  Meningitis caused by bacteria is usually severe and often very contagious from one human being to another. There are vaccines available for some kinds of bacterial meningitis such as meningococcal meningitis. This was a common form of meningitis in college students living in dorms and recruits attending boot camp. Meningococcal meningitis is so contagious that even close contacts of the patient need to be treated with antibiotics.

      Fungal meningitis is very rare and usually only occurs in patients whose immune system is suppressed. The fungal meningitis infections that have occurred recently in this country were caused when a fungus contaminated a solution of steroids that were injected into the fluid around the spinal cord to control pain from other conditions. The fungus then grew and infected the coverings of the cord. This type of meningitis is not contagious from one human to another, but, as with all fungal infections, it can be very difficult to treat.