Microbial Diseases of the Nervous System

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Microbial Diseases of the Nervous System

• Chapter 22
• Lecture 20

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I. Structure and Functions of the Nervous System

• The central nervous system consists of the
  ________and _______ _____
• Both are enclosed in bone skull and backbone
• Abbreviated _______
• Branching from the CNS are the nerves of the
  Peripheral Nervous System
• Abbreviated _______

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CNS and PNS
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I. A. The CNS

• 1.Covered by three layers of membranes
• A. ____________
• Dura mater
• Arachnoid
• Pia mater
• B. Cerebrospinal Fluid (_______) circulates
  between the arachnoid and the pia mater in what
  is called the subarachnoid space and in the
  ventricles of the brain

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The CNS and The Meninges
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I. B. Blood/Brain Barrier

• 1. Antibiotics are usually prevented from
  entering the brain-many other substances as well.
• 2. _________________ enter through
• Trauma
• Along peripheral nerves
• Through blood and lymph
• 3. Meningitis infection of the __________
• 4. Encephalitis infection of the _________

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II. Bacterial Diseases of the Nervous System

• A. Meningitis
• Viral
• Protozoal
• Bacterial-nearly ________ species!
• Haemophilus influenzae
• Streptococcus pneumoniae
• Neisseria meningitidis

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II.A. 1. Haemophilus influenzae Meningitis

• H. influenzae is part of normal throat microbiota
• _____ types based on _______ differences
• All require blood factors for growth
• Type b most common in children under 4 years of
  age
• Vaccine directed against capsule is available
  (What does that mean?)

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Effect of vaccine
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II.A.2. Neisseria Meningitis (Meningicoccal
Meningitis)

• Throat organism in many _____ people
• Enter probably enter through bloodstream-found in
  _______ in CSF
• ________ causes symptoms, most common in young
  children
• Epidemics in the military-vaccines are given to
  military recruits

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N. meningitis in throat
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II. A. 3. Streptococcus pneumoniae Meningitis
(Pneumococcal Meningitis)

• S. pneumoniae is commonly found in the
  ____________
• Hospitalized patients and young children most
  vulnerable-rare but has a _________mortality rate
• Vaccine is somewhat effective

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II. B. Diagnosis and Treatment

• Cephalosporins given before specific ___________
  is identified
• Penicillin and Rifampin
• CSF is _______ stained and serological tests are
  done
• Cultures are done on ______ ______ and incubated
  at low oxygen levels

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II. A. 4. Listeriosis Meningitis

• Newborns ( may cross the placenta)
• Pregnant women
• Immunosuppressed people
• Caused by _________ monocytogenes in contaminated
  food

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Cell to cell spread of Listeria
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Summary of meningitis
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II. C. 1. Tetanus

• Wound infection by _________ __________
• Produces n__________ tetanospasmin which cause
  contraction of the jaw muscles and may cause
  death from spasms of the respiratory muscles
• A____________organism grows in deep wounds with
  little bleeding
• DPT immunization includes tetanus toxoid
• Upon injury may receive a booster of toxoid or
  immune globulin

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Tetanus toxin inhibits muscle relaxation
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II C. 2 .Botulism

• Exotoxin made when C. botulinum grows on food
• Various serotypes-Type A is the most virulent
• Toxin _________ nerve transmission
• Blurred vision in 1-2 days, then progressive
  paralysis for 1-10 days, lethal from respiratory
  and cardiac failure
• Toxin is heat labile and is destroyed by
  _________ for 5 minutes
• Acids, nitrites or aerobic conditions inhibit
  growth
• Wound and infant botulism are possible

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II. C. 3.Leprosy

• Called Hansens Disease, caused by __________
  leprae
• Mainly occurs in the tropics
• Cultured in ______________!
• T_______________ form areas of nodules and loss
  of sensation in skin
• L_______________ form disseminated nodules and
  tissue necrosis
• S_______ drugs, not highly contagious, untreated
  individuals often die from secondary infections
  such as tuberculosis

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Leprosy
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III. Viral Diseases of the Nervous System

• A. Poliomyelitis
• B. Rabies-a rhadovirus
• C. Arboviral infections

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III A. Poliomyelitis

• Usual symptoms
• Headache, sore throat, stiffness of back and neck
• Less than ______ of cases paralysis
• Transmitted by ______ contamination of water
• Virus invades the lymph nodes of the neck and
  small intestine
• Diagnosis made by isolation of the virus from
  feces and __________secretions

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Iron lungs in the 50s
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III. A. 1. Polio vaccines

• Salk Inactivated PV ________ inactivated
  viruses, boosters every few years
• Sabin Oral Polio Vaccine contains three _____
  _________ which have been attenuated

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Polio Vaccines
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III. B. Rabies

• Acute, usually _______ encephalitis
• Usually contacted through the bite of a rabid
  animal, can be contacted through _________, or
  invasion of tissue though __________ abrasions
• Virus first multiplies in skeletal muscles and
  connective tissues
• Virus then moves along peripheral nerves to the
  ________
• Symptoms include _________ of the mouth, throat
  then extensive brain and spinal cord damage

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Rabies cont.

• Diagnosis is made from saliva, serum, CSF or
  brains smears
• Reservoirs include skunks, bats foxes and
  raccoons
• Cattle, dogs and cats may get rabies
• Rabbits and all rodents rarely get rabies
• Preexposure vaccination
• Post exposure human rabies immune globulins and
  IM injection of vaccine

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Rabies
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Rabies
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III. C. Arboviral Encephalitis

• Chills, headache, fever and coma
• Transmitted by ___________
• Summer months are when mosquitoes are active
• Horses get EEE and WEE viruses
• Control by means of __________ control

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Arboviral Encephalitis
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Types of arboviral encephalitis
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IV. Fungal Diseases of the Nervous System

• A. Cryptococcus neoformans causes a meningitis-
  it is a _______ ________ encapsulated fungus
• Dried infected ________ droppings-begins as a
  lung infection and may spread to brain and
  meninges
• Immunosuppressed individuals are most susceptible

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Cryptococcus neoformans
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V. Protozoan diseases of the Nervous System

• A. African sleeping sickness Trypanosomiasis-
  transmitted by the bite of the Tsetse fly
• Cause lethargy and then coma
• Protozoan changes its surface antigens -has
  evolved this way to avoid the _______
  system-makes ________ development difficult

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Trypanosomiasis
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V. B. Naegleria meningoencephalitis

• N. fowleri almost always _________
• Invades the brain from the _______ _________
• Usually encountered in streams or ponds
• Recent out break in Arizona-usually only a few
  cases in US per year
• Two young boys died-not related to each
  other-using the same source of domestic water

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Naegleria
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VI. Nervous System Diseases caused by Prions

• A. Spongiform degenerations
• Scrapie in sheep
• Bovine _______________ encephalopathy
• B. Human diseases Creutzfeld-Jakob and Kuru (in
  ________ cannibals) are human diseases similar to
  Scrapie and BSE
• Recall that prions are self-replicating
  _____________!

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Incineration
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Spongiform encephalopathies
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Microbial diseases
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Microbial diseases