Microbiology: A Systems Approach, 2nd ed'

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Microbiology A Systems Approach, 2nd ed.

• Chapter 19 Infectious Diseases Affecting the
  Nervous System

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19.1 The Nervous System and Its Defenses

• Two component parts to the nervous system
• CNS
• PNS
• Three important functions
• Sensory
• Integrative
• Motor
• Brain and spinal cord made up of neurons, both
  surrounded by bone, encased with meninges
• PNS cranial and spinal nerves

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Defenses of the Nervous System

• Mainly structural
• Bony casings
• Cushion of CSF
• Blood-brain barrier
• Immunologically privileged site

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Protozoan and Fungal Diseases

• Toxoplasmosis
• African Sleeping sickness
• Cryptococcosis

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Toxoplasma gondii

• Flagellated parasite
• Most cases go unnoticed
• In the fetus and immunodeficient people, severe
  and often fatal
• Asymptomatic or marked by mild symptoms such as
  sore throat, lymph node enlargement, and
  low-grade fever

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Figure 19.13
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African Sleeping Sickness

• Trypanosoma brucei
• Also called trypanosomiasis
• Affects the lymphatics and areas surrounding
  blood vessels
• Usually a long asymptomatic period precedes onset
  of symptoms
• Symptoms include intermittent fever, enlarged
  spleen, swollen lymph nodes, and joint pain
• Central nervous system is affected with
  personality and behavioral changes that progress
  to lassitude and sleep disturbances

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Figure 19.24
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Cryptococcus neoformans

• Fungus
• More chronic form of meningitis
• More gradual onset of symptoms
• Sometime classified as a meningoencephalitis
• Headache- most common symptom also nausea and
  stiff neck
• Spherical to ovoid shape and a large capsule

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Figure 19.7
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Coccidioides immitis

• At 25C forms a moist white to brown colony with
  abundant, branching, septate hyphae
• Hyphae fragment into arthroconidia at maturity
• Usually begins with pulmonary infection

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Figure 19.9
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Figure 19.10