Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.
Our brain, the spinal cord, and its surrounding structures could become infected by a large spectrum of germs (that is, microorganisms). Bacteria and viruses are the most common offenders. Parasites, fungi, and others can infect the central nervous system (CNS), although more rarely.
Location: The infecting germ causes an inflammation of the area invaded. Depending on the location of the infection, different names are given to the diseases.
Meningitis is the inflammation of the meninges, the surrounding
three-layered membranes of the brain and spinal cord, and the fluid it is bathed in, called cerebrospinal fluid
Myelitis actually means a spinal cord inflammation.
Abscess is an accumulation of infectious material and offending microorganisms within the CNS.
Type: Organisms may cause bacterial, viral, parasitic, fungal, or prion infections of the central nervous system.
Usually, viral meningitis causes milder symptoms, requires no specific
treatment, and goes away completely without complications. Viral infections are
two to three times more common.
Bacterial meningitis is a very serious disease and may result in a learning disability, speech defects, hearing loss, seizures, loss of extremity function or amputation, permanent brain damage, and even death. According to the World Health Organization (WHO) statistics, up to 15% of
the survivors of bacterial meningitis remain with permanent complications and health issues, as described above.
In the U.S., the overall incidence of bacterial meningitis decreased significantly since 1998, mostly as a result of widespread vaccination, from about 25,000 cases yearly to about 4,100 cases. About two-thirds of all cases are in children. Bacterial meningitis usually occurs in isolated cases without epidemics. It is more common in males than females and is more likely in late winter and early spring.
Worldwide, bacterial meningitis is common. It continues to be a serious threat to global health. The most recent statistics published by
the WHO in 2010 estimates up to 170,000 annual deaths from bacterial meningitis
worldwide. It particularly affects the African continent, with regular epidemics
in sub-Saharan and West Africa, known as "the meningitis belt."