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  • 1. Gas Gangrene
    • Epidemiology
      • War wounds; dirt contamination of wounds, tissue death, impaired circulation in patients with poor circulation
      • Common after:
      • Arteriosclerosis, diabetes predispose
      • 40% mortality (with therapeutic care)
    • Prevention and treatment
      • Prompt cleaning of wounds is:
      • Surgical removal of dead and infected tissues
      • Treatment with hyperbaric oxygen, antitoxin
      • Penicillin to kill vegetative C. perfringens
  • 2. Plague
    • Symptoms
      • Sudden onset of high fever, large lymph nodes (buboes) , skin hemorrhages, severe cough, bloody and frothy sputum
    • Pathogen – Yersinia pestis
      • Capsulated bacterium, multiple virulence factors
      • Virulence factors:
    • Pathogenesis
      • Y. pestis contracted from bite of infected flea
      • Survive phagocytosis and infect lymph nodes ->
      • May be carried into bloodstream ->
      • Hemorrhages under skin result in dark patches, skin color
      • Lung infection -> contagious, lethal pnuemonic plague ->
  • 3. Transmission of Yersinia pestis
  • 4. Yersinia pestis
  • 5. Plague
    • Epidemiology
      • Endemic in wild animals and fleas
      • Rare but
      • Transmitted person to person via fleas
      • Pneumonic plague: coughing –
    • Prevention and treatment
      • Vaccine offers short-term protection
      • Avoid contact with wild rodents
      • Insecticides and rat control
      • to prevent high mortality
  • 6. Lyme Disease – Phases
    • Phase 1:
    • Erythema migrans characteristic rash present – 80% of cases
    • Malaise; chills; fever; headache; stiff neck; joint and muscle pain; backache
    • Phase 2:
    • Cardiac dysfunction
    • Neurological symptoms (meningitis, encephalitis, peripheral nerve neuropathy
    • Phase 3:
    • Arthritis; joint pain, tenderness, swelling
    • Chronic nervous system impairments
  • 7. Lyme Disease – Borrelia burgdorferi
  • 8. Lyme Disease
    • Causative Agent
      • Borrelia burgdorferi – microaerophilic spirochete
    • Pathogenesis
      • Spirochetes injected into skin:
      • Multiply ->
      • Tissue damage result of immune response
  • 9. The life cycle of Ixodes
  • 10. Ixodes scapularis – Black-legged tick
  • 11. Lyme Disease
    • Epidemiology
      • Increased prevalence – encroachment on wooded areas; increase in deer populations
      • Spread by infected tick bite –
      • Ixodes – preferred host: white-footed mouse, white-tailed deer
    • Prevention and Treatment
      • Prevent by:
      • Antibiotics are effective:
        • Penicillin, doxycycline
      • Prolonged antibiotics late in infection may be curative
  • 12. Lyme disease in the U.S.
  • 13.
    • Viral infections of the cardiovascular system
  • 14. Mononucleosis
    • Symptoms
      • Fatigue , fever, sore throat , lymph node enlargement
      • Most people return to school/ work:
    • Causative agent – Epstein-Barr virus (EBV)
      • dsDNA virus, herpesvirus family
      • Isolated from Burkitt’s lymphoma
    • Pathogenesis
      • Virus enters throat ->
      • Infection of B cells ->
      • Hemorrhage of spleen is rare but serious complication
      • May play role in causing malignant tumors –
  • 15. Diseases associated with Epstein-Barr virus
  • 16. Mononucleosis
    • Epidemiology
      • Spread in:
      • Kissing is common mode of transmission
      • Lifelong recurrent shedding of virus in saliva
      • Very common in college students
    • Prevention and treatment
      • Avoid sharing items contaminated by saliva
      • Acyclovir beneficial in some cases
  • 17. Viral Hemorrhagic Fevers
    • Signs and symptoms – Fever, fatigue, dizziness, muscle pain, exhaustion
      • Minor petechiae
      • Severe internal hemorrhaging and bleeding from mouth, eyes and ears
      • Death from:
    • Pathogens – ssRNA viruses – Filoviridae family
      • Enveloped, filamentous virus
    • Pathogenesis
      • Hemorrhaging due to malfunction of blood clotting system
      • Infected macrophages trigger localized blood clotting ->
  • 18. Viral Hemorrhagic Fevers
    • Epidemiology
      • Primarily in Africa
      • No human carriers but natural animal hosts
      • Transmission through:
      • Airborne?
      • Ebola – 90% fatal
      • Marburg – 25% fatal
    • Prevention and Treatment
      • No effective antiviral drugs
      • Currently no vaccine for humans
    Ebola virus
  • 19. Some viral hemorrhagic fevers
  • 20. Sites of Marburg and Ebola virus epidemics