[ 2 ] Microbial Diseases of the Nervous System

• Bacterial Meningitis - Can be caused by viruses, bacteria, fungi, and protozoa. Symptoms are due to endotoxin, the disease occurs most often in young children
• H. Influenzae

  Part of the normal throat microbiota

  Requires blood factors for growth; serotypes are based on capsules

  Type B of this bacteria is the most common cause of meningitis in children under

  4 years old.

  • A conjugated vaccine directed against the capsular polysaccharide antigen is

  available
• S. Pneumoniae

  Commonly found in the nasopharynx

  Young children are most susceptible to S. Pneumoniae meningitis(Has a high

  mortality rate if untreated)

  • A conjugated vaccine is available
• N. Meningitidis

  Causes meningococcal meningitis.

  Found in the thoughts of healthy carriers, and transmitted by droplet aerosols or

  direct contact with secretions

  Probably gain access to the meninges through the bloodstream, may be found in

  leukocytes in CSF

  • Purified capsular polysaccharide vaccine against serotypes A, C, Y and W-135 is

  available
• Tetanus

  • Caused by a localized infection of a wound by Clostridium tetani
• Botulism

  • Caused by an exotocin produced by C. Botulinum growing in foods
• Leprosy (Hansen’s DIsease)

  • Caused by Mycobacterium Leprae
  • The tuberculoid form of the disease is characterized by loss of sensation in the skin surrounded by nodules
• Poliomyelitis (Polio) - Symptoms are usually sore throat and nausea

  Fewer than 1% of cases includes paralyis

  Transmitted by the ingestion of water contaminated with feces.

  First invades lymph nodes of the neck and small intestine.

  May be followed by VIremia and Spinal cord involvement

  Diagnosis is based on isolation of the virus from feces and throat secretions.

  • Untreated individuals often die of secondary bacterial complications, such as

  tuberculosis
• Rabies

  • Caused by Lyssavirus
• Arboviral Encephalitis - Symptoms are chills, headache, fever, and eventually coma. Many types of viruses(arbovruses) transmitted by mosquitos cause encephalitis
• Cryptococcus neoformans Meningitis (Cryptococcosis)

  Cryptococcus spp. are encapsulated yeastlike fungi that cause cryptococcosis. May be contracted by inhaling dried infected pigeon or chicken droppings
• African Trypanosomiasis - caused by Trypanosoma brucei gambiense

  T.b rhodesiense. Transmitted by the bite of the tsetse fly
• Amebic Meningoencephalitis - Encephalitis caused by the protozoan Naegleria fowleri is almost always fatal
• Prions - are self-replicating proteins with no detectable nucleic acid
• Chronic Fatigue Syndrome (CFS) - Also known as Myalgic Encephalomyelitis (ME). It was previously dismissed as psychological but is now recognized as strongly linked to

  the immune system and possibly genetic.