MBI 111 Microorganisms and Human Disease

Impact of Infectious Diseases on Development of Human Societies

Antiquity to Middle Ages

• Emigration from rain forests -

• Elimination of prey and "weeds" -

• Development of endemic levels of infectious diseases made regions biological threats to others, which may have simplified territorial expansion

• Early thoughts about cause and transmission of infectious diseases
  • Egyptians and Indians - diseases are punishments inflicted by gods

  • Hippocratic school (400BC-500AD) - imbalance of the four "humors"

• Impact of selected diseases
  • African sleeping sickness - reason for few people in Savannahs?

  • Malaria - contributed to decline and fall of Rome

  • Schistosomiasis - prevalent in Egypt from time of irrigation

  • Leprosy - quarantine starts here?

  • Plague - contributed to decline and fall of Rome; delayed development of medicine and germ theory of disease
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Middle Ages to Dawn of Microbiology as a Science

• Exploration, mass migration and war vs. disease

• Impact of selected diseases
  • Plague
    • killed 27M Europeans in 1346-1361 (pilgramages)

    • returned in 1665-1666, killed 2000 people/week

  • Malaria - US, colonial-19th century, east-midwest

  • Smallpox
    • many gods and a patron saint of smallpox victims

    • crusaders - smallpox succeeded plague, leprosy and syphilis as leading pestilence 1500s-1700s - killed ~400,000 per year

    • variolation led to vaccination

  • Impact of European diseases on the New World - smallpox, measles, mumps, typhus, scarlet fever

  • Impact of New World diseases on Europe - syphilis

  • Tuberculosis
    • Stone Age and Egyptian skeletons

    • fostered prejudice in India, Greece and Rome

  • Cholera
    • religious rituals

    • John Snow and the London cholera epidemic of 1849

• Development of medical concepts - syphilis, smallpox, cholera

Era of Public Health to Discovery of Antibiotics

• Advances in microbiology that fostered development of public health
  • Development of the Germ Theory of Disease
    • Greek and Roman physicians

    • Fracastoro ~1530

    • Bassi - Botrytis bassiana causes il segno in silkworms

    • Semmelweis - puerperal fever

    • Pasteur - wine, etc., 1865-1871

    • Koch - anthrax, 1876

  • Water purification, sewage collection and treatment
    • Roman sanitation

    • other public sanitation facilities

  • Development and applications of immunology concepts
    • Pasteur - vaccines (1881-1885)

    • Metschnikoff - phagocytes, 1884

    • von Behring and Kitasato - antibodies, 1890

  • Discovery and development of early antimicrobial agents
    • Ehrlich - salvarsan, 1908

    • Flemming - penicillin, 1929

    • Domagk - prontosil ∧ sulfanilamide, 1935

    • Chain and Florey - penicillin, 1941

• Impact of selected diseases
  • Typhoid and dysentery - affected outcome of war and influenced balance of political power
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  • Tuberculosis - leading cause of death in US in 1900
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  • Influenza - 1918-1919 pandemic
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Last 50 Years

• Many new antimicrobial agents discovered in last 50 years

• Current public health methods include:
  • Water purification and sewage treatment
    • water purification
      • physical

  • chemical

  • sewage treatment
    • physical

  • biological

  • chemical

• Vaccination
  • DTP

  • Polio

  • MMR

  • Influenza

  • Hib

  • Hepatitis b

  • Chickenpox

• Decline of public health infrastructure

• Impact of selected diseases
  • AIDS - brand-new or ~200 years old?

  • Dengue Fever - moving in on us?

  • Ebola - more trouble in Africa!

  • Hantavirus Pulmonary Syndrome - Asian or worldwide?

  • Lyme Disease