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Nervous System Diseases



The nervous system consists of the central nervous system (CNS)—the brain and spinal cord—and peripheral nervous system (PNS)—the peripheral nerves. It receives information about the body and environment, processes it, and controls body actions. Infections of the nervous system are caused by bacteria, viruses, fungi, protozoa, and prions, which are infectious misfolded proteins. Bacterial diseases of the nervous system include the specialized Clostridium infections and several infections causing meningitis, which is inflammation of the tissues surrounding the brain. Rabies and polio are caused by viruses, and numerous viruses result in encephalitis, which is inflammation of the brain itself. Misfolded infectious proteins called prions only cause central nervous system disease. African sleeping sickness and amoebic meningitis are caused by protozoa.

At A Glance

  • The nervous system consists of the central nervous system (CNS), which is made up of the brain and spinal cord, and the peripheral nervous system (PNS), which is made up of the cranial and peripheral nerves, along with their sensory and motor endings.
  • Normally, the nervous system receives information from the body and environment, processes it, and transmits information back to the body. Phagocytic microglial cells and the thick-walled capillaries of the blood-brain barrier maintain a sterile central nervous system in healthy individuals.
  • Infectious neurological diseases may result from viruses, prions, bacteria, fungi, and other eukaryotic parasites, and despite these widely differing causative agents, there are many common symptoms and pathologies.
  • Tetanus, an infection caused by the bacterium Clostridium tetani, may be fatal if untreated.
  • Botulism, a disease caused by the toxins released by the bacterium Clostridium botulinum, is fatal if untreated.
  • Meningitis is an infection that affects the protective tissues surrounding the brain and spinal cord called meninges.
  • Viral infections of the nervous system include the single-causative-agent diseases rabies, polio, and leukoencephalopathy and the disorders encephalitis and meningitis, which are caused by a wide range of viruses.
  • Rabies is a viral infection spread through animal bites that is fatal without treatment.
  • Poliomyelitis, or polio, is a viral disease that affects the central nervous system and may or may not be fatal but can have permanent effects.
  • Fungi and protozoa may cause nervous system diseases, and while they tend to be rare in developed regions, these diseases are often life-threatening, especially in immunocompromised populations.
  • African sleeping sickness, a disease caused by parasites in genus Trypanosoma, is fatal, and treatments for it may also be fatal.
  • Prion diseases, for which there are no known treatments or cures, are caused by misfolded proteins that cause the proteins around them to become misfolded as well.