Q4MBIO | LESSON 2

• Can be caused by viruses, bacteria, fungi, and protozoa.

  Three major causes are:

  • Haemophilus Influenzae
  • Streptococcus Pneumoniae
  • Neisseria Meningitidis

  Symptoms are due to endotoxin, the disease occurs most often in young children

  Bacterial Meningitis
• • 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

  H. Influenzae (A BACTERIAL MENINGITIS)
• • 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


  S. Pneumoniae (A BACTERIAL MENINGITIS)
• • 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


  N. Meningitidis (A BACTERIAL MENINGITIS)
• • Caused by a localized infection of a wound by Clostridium tetani
  • C. tetani produces the neurotoxin tetanospasmin, which causes the symptoms of tetanus: spasms, contraction of muscles controlling the jaw, and death resulting from spasms of respiratory muscles
  • C. tetani is an anaerobe that will grow in deep unclean wounds


  TETANUS
• • Caused by an exotocin produced by C. Botulinum growing in foods
  • C. botulinum will not grow in acidic foods or in an aerobic environment
  • Adding nitrites to foods inhibits the growth of C. botulinum
  • The toxin is heat labile and is destroyed by boiling for 5 minutes

  Botulism
• • Caused by Mycobacterium Leprae
  • M. leprae has never been cultured on artificial media
  • M. leprae can be cultured in armadillos and mouse footpads.
  • Leprosy is not highly contagious and is spread by prolonged contact with exudates.
  • Untreated individuals often die of secondary bacterial complications, such as tuberculosis


  Leprosy (Hansen’s DIsease)
• Bacterial Diseases of the Nervous System

  1. Bacterial Meningitis (H. Influenzae, S. Pneumoniae, N. Meningitidis)
  2. Tetanus
  3. Botulism
  4. Leprosy (Hansen’s DIsease)
• • 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.

  Poliomyelitis (Polio)
• • Caused by Lyssavirus
  • Other genotypes of Lyssavirus cause rabies-like diseases
  • May be contracted through the bite of a rabid animal or invasion through skin.
  • Encephalitis occurs when the virus moves along peripheral nerves to the CNS(Central Nervous System)
  • Symptoms of rabies include spasms of mouth and throat muscles followed by extensive brain and spinal cord damage and death

  Rabies
• • Symptoms are chills, headache, fever, and eventually coma.
  • Many types of viruses(arbovruses) transmitted by mosquitos cause encephalitis
  • Incidence of arboviral encephalitis increases in the summer months, when mosquitos are most numerous
  • Notifiable arboviral infections are: Eastern equine encephalitis (EEE) - Western equine encephalitis (WEE) - St. Louis encephalitis (SLE) - California encephalitis (CE) - West Nile virus (WNV)

  Arboviral Encephalitis
• Viral Diseases of the Nervous System

  1. Poliomyelitis (Polio)
  2. Rabies
  3. Arboviral Encephalitis
• • Cryptococcus spp. are encapsulated yeastlike fungi that cause cryptococcosis
  • May be contracted by inhaling dried infected pigeon or chicken droppings
  • The disease begins as a lung infection and may spread to the brain and meninges
  • Diagnosis is based on isolation of the virus from feces and throat secretions
  • Immunosuppressed individuals are most susceptible to cryptococcosis
  • Diagnosis is based on latex agglutination tests for cryptococcal antigens in serum or CSF

  Cryptococcus neoformans Meningitis (Cryptococcosis)
• Fungal Diseases of the Nervous System

  1. Cryptococcus neoformans Meningitis (Cryptococcosis)
• • Caused by: - Trypanosoma brucei gambiense - T.b rhodesiense
  • Transmitted by the bite of the tsetse fly
  • Affects the nervous system of the human host causing lethargy and eventually coma
  • Commonly called sleeping sickness
  • Vaccine development is hindered by the protozoan’s ability to change its surface antigens

  African Trypanosomiasis
• • Encephalitis caused by the protozoan Naegleria fowleri is almost always fatal
  • Granulomatous amebic encephalitis, caused by Acanthamoeba spp. and Balamuthia mandrillaris, is a chronic disease

  . Amebic Meningoencephalitis
• Protozoan Diseases of the Nervous System

  1. African Trypanosomiasis
  2. Amebic Meningoencephalitis
• • Prions are self-replicating proteins with no detectable nucleic acid
  • Diseases of the CNS that progress slowly and cause spongiform degeneration are caused by prions
  • Transmissible spongiform encephalopathies are caused by prions that are transferable from one animal to another
  • Both diseases has no treatment and prevention

  DISEASES:

  1. Creutzfeldt-Kakob Disease
  2. Kuru


  Nervous System Diseases Caused by Prions
• • Symptoms include:

  1. Fatal Infection
  2. Trembling

  • Can be transmitted by Inheritance, ingestion, and transplants

  Creutzfeldt-Kakob Disease
• Disease Caused by Unidentified Agents

  Chronic Fatigue Syndrome
• • 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.
  • CFS often begins with flu-like symptoms
  • May be triggered by viral illnesses

  Chronic Fatigue Syndrome