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Chapter 25 Infections of the Nervous System

Chapter 25 Infections of the Nervous System. The Nervous System. Figure 25.1. Meningitis. Organisms Neisseria meningitidis meningococcal Haemophilus influenzae Streptococcus pneumoniae pneumococcal E. coli Pathogenesis inflammation of the meninges membrane brain and spinal cord

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Chapter 25 Infections of the Nervous System

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  1. Chapter 25Infections of the Nervous System

  2. The Nervous System Figure 25.1

  3. Meningitis • Organisms • Neisseria meningitidis • meningococcal • Haemophilus influenzae • Streptococcus pneumoniae • pneumococcal • E. coli • Pathogenesis • inflammation of the meninges membrane • brain and spinal cord • sudden fever, severe headache, neck rigidity • treatment--immediate antibiotics

  4. Meningitis • Aseptic meningitis • viral origin • Cryptococcal meningitis • Cryptococcus neoformans

  5. Organism Clostridium tetani Spore former Anaerobic growth deep wounds decaying tissue Pathogenesis tetanospasmin neurotoxin ink dot enough for 30 deaths contraction of muscles spastic paralysis lockjaw respiratory distress Tetanus

  6. Tetanus • Treatment • before clinical symptoms • antitoxin • blocks toxin • after clinical symptoms • no treatment • Prevention: • vaccine every 5-10 years • toxoid • develop antibodies against toxin, not organism

  7. Organism Clostridium botulinum spores many places growth inhibited by low pH Pathogenesis blocks release of acetylcholine interferes with nerve impulse paralysis of respiratory muscles mortality 35% Botulism

  8. Botulism • Different types of toxin • produced by different strains of C. botulinum • Type A • most potent • west of Mississippi River • Age associated • infant botulism • differences in normal biota • adult botulism • food poisoning • heat-labile toxin

  9. Rabies • bullet-shaped morphology • epidemiology • reservoir: all mammals • humans: end of infectious cycle • control • reduce exposure of virus in animals • wild mammals--uncontrollable reservoir • bats--dormant for long periods • domestic--vaccine • diagnosis: serology/brain tissue (negri body) • treatment: vaccine and immune globulin (RIG)

  10. Poliomyelitis • Pathogenesis • alimentary phase--primary multiplication • lymphatic phase--tonsils, lymph nodes • viremic phase--spread in blood • neurological phase--CNS, extraneural tissue • requires persistent viremia • low levels of antibodies prevent spread • >l% of infections lead to severe paralytic infection • two vaccines • oral (OPV)--attenuated--Sabin • injected (IPV)--inactivated--Salk • eradication schedule--2000

  11. Encephalitis • Arboviruses • Eastern Equine Encephalitis (EEE) • severe • Western Equine Encephalitis (WEE) • California Encephalitis (CE) • St. Louis Encephalitis (SLE) • Japanese B encephalitis • endemic areas of Asia • mosquito borne • Other viruses • West Nile Virus

  12. Spongiform encephalopathy • Prions • infectious proteins • Diseases: • Creutzfeldt-Jakob disease (CJD) • Kuru • Scrapie (sheep) • Bovine spongiform encephalitis (mad cow)

  13. African Trypanosomiasis • Sleeping Sickness • Trypanosoma brucei gamiense • Trypanosoma brucei rhodesiense • Protozoa • Transmitted by tsetse fly • multiply in fly • tyrpanosome enters blood • spread to spleen, lymph nodes, liver • invade CNS • coma and death

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