This is for chrisbenjamin

profileshenmegui
hist2613.week02.pathology_1.ppt
Home>History homework help>This is for chrisbenjamin

Disease, Medicine and History: The Field of Pathology

Thinking About Disease —The History of Pathology

What is Pathology

  • Definition: From the Greek words for ‘suffering’ and ‘theory about’, literally translates as the theory of suffering. But the meaning has narrowed to represent material knowledge about disease.
  • While medicine is not a science, but an applied technology or even an art; it is closely linked to science through pathology (the science of disease)
  • Functions of Pathology:
  • 1) Explain Suffering: Why do we get sick? Illness demands a ‘logical’ explanation—either cultural/spiritual ideas of sin and blame, or material and ‘scientific’ ideas of structure, function, heredity, contagion and risk.
  • 2) Identify, or define an ailment. What are the signs of a particular ailment—links to diagnosis and prognosis. Also creates relationship between ‘Abnormal’ bodies and a ‘Normal’ body (These definition change over time and are related to cultural values as well as scientific knowledge.)

Fifteenth-Century Illustration of the Symptoms of Syphilis

The Functions of Pathology, cont.

Fifteenth-Century Manuscript on Caring for Lepers

  • 3) Used to Predict Outcomes. In past times an accurate prognosis was at least as important as the ability to cure (divine knowledge). Prognosis is still important, but couched in statistics derived from experience of a cohort defined by age, gender, diagnosis. (Egs. five-year survival period, or a 80% mortality rate).
  • 4) Used to justify treatments. Most treatments discovered through observation, not reasoning.
  • 5) Use to prove explanations, diagnosis, course of action. Also linked to use of postmortem examinations. In Europe autopsies used for retrospective diagnosis trace back to 13th century. Within both legal and medical systems, autopsy the ultimate challenge of our knowledge system—Was diagnosis correct? Could anything else have been done? Tied to malpractice.

Theories of Disease

  • Illness: ‘Individual suffering’—illness exists as the real suffering felt by a person.
  • Disease: ‘Ideas about illness’—disease exists only as a theory constructed to explain the illness, its presumed cause, and its target.
  • Semantics? No! Important distinction in the philosophy of medical knowledge, or medical epistemology—the study of how we know what we think we know.
  • Organismic or Individual Theory of Disease—Dominates medical practice. Holds that diseases are bad, discontinuous and affect individuals. Addresses target of disease, but not cause.
  • Causation Theories:
  • 1) Ontological (Outside the patient, diseases vary one from another, and they exist separate from the patient. From Greek verb ‘to be’—thus, idea of disease as a separate entity. What the patient has, is the key question.)
  • 2) Physiological (Causes emerge from inside the patient, that patients vary, and that diseases do not exist separate from patients. Who the patient is, is the key question.)

John Chapman Painting of Pathology, Early 1800s

History of Pathology (1) Ancient to Medieval Ages

  • Generally the construction of disease concepts has moved from spiritualistic accounts of nature, to careful bedside descriptions of illness, and then to the laboratory structure of ‘modern’ medicine.
  • Myths and Deities:
  • A) Homer—the Iliad (c. 700 BC)—deadly pestilence that strikes Greeks who had ransomed a priest’s child.
  • B) Bible—Old Testament story of Job (8th century BC)—his family, wealth and health are all taken as a test of faith.
  • Legacies of older (supernatural) ideas remain, such as concepts of ‘sin’, that suffering or ‘trials’ of living with ailments are tests and build character.
  • Greco-Roman World:
  • 1) Gods, the 4 elements, and the 4 humours (balance=health; disease=imbalance)
  • 2) Clinical observation: Work and Ideas of Hippocrates (the ‘sacred’ disease, epilepsy)
  • 3) Move to physiological explanations
  • 4) Nosology (disease=patterns of suffering)
  • 5) Ancient and Arabic encyclopedic works

Medieval Illustration of an Angel Treating a Leper

Aristotle’s View of the 4 Humours

History of Pathology (2) Renaissance to the Early 19th Century

  • Renaissance: Decline of spiritualistic and vitalistic explanations of natural world. Hippocratic observation was glorified, while rigid Galenism waned (along with interdictions against human dissection). Growth of new science of chemistry, and most of all the new system of diagnosis called nosology—careful observation of symptoms.
  • A) Work of Thomas Sydenham—English physician, wrote in Latin on fevers—emphasized the importance of observation and dangers of theory. Although mentioned the humours, key was diseases as independent of patients. His career and writing marked start of a era of nosologists.
  • Pathology in the Morgue (‘Altered Anatomies’). During 1600s and 1700s Italian and Swiss physicians published books that were collections of abnormal anatomies.
  • 19th Century:
  • 1) Move to ‘normal’ ranges of health, not all patients would have all the symptoms
  • 2) Classic and named diseases (eg. Hodgkin’s disease)
  • 3) Three dimensional anatomical images

Thomas Sydenham (1624-1689)

Renaissance Dissection – Pathology in the Morgue

History of Pathology (3): Germ Theory to the Laboratory

  • The Microscope and the move to exploring the body at the level of tissues
  • Cell Theory (German physician Rudolph Virchon—studied tumors, and concluded that the anatomy and physiology of a single cell was passed on to all of its ‘daughter’ cells.)
  • Germ Theory (Ontological View of Disease): Shifted the cause of disease away from internal organs to external invaders.
  • 1) Louis Pasteur (French Chemist) who studied fermentation to refute notion of spontaneous generation of living organisms—demonstrated link between bacteria and disease (public demonstrations of inoculation of animals). But doctors skeptical—germs even in the healthy, and he was not a physician!
  • 2) Joseph Lister (British Surgeon) used carbolic acid to kill germs and seal wounds—1865 operation published in the Lancet (acceptance of antiseptic technique gradually spreads)
  • 3) Robert Koch (German Physician), in 1882 identified mycobacterium tuberculosis as cause of pulmonary tuberculosis. Established Four Postulates to establishing bacterium as a cause of disease. 1) Bacteria must be found in every case; 2) Must be isolated and grown in pure culture; 3) Must produce same disease when injected into animals; 4) Must be recovered in all experimental cases.
  • Opponents to germ theory noted that heredity and vaccines could create or alter natural susceptibility to infections: Therefore infection with germs had something to do with both host and the invader.
  • Genetics: In early 20th century, found that some diseases ‘ran in families’—following Gregor Mendel’s laws of heredity (Egs. Tay-Sachs disease, sickle-cell anemia, muscular dystrophy, cystic fibrosis.)

Louis Pasteur (1822-1896)

History of Pathology (4) William Osler & William Boyd

  • Over course of 19th century, microscopic anatomy, bacteriology, immunology, and genetics led pathology further into the laboratory—a trend that was championed by Canadians.
  • Sir William Osler: Appointed pathologist at McGill University in 1874, and two decades later was a founder of Johns Hopkins medical school in Baltimore. New system of education: 2 years of basic science, followed by 2 years of clinical training. His work, Principles and Practice of Medicine (1892) exemplified the blend of scientific pathology and insightful clinical descriptions—the most influential textbook of the early 20th century.
  • William Boyd: Scottish-Canadian pathologist, famous for pathology textbooks—the first was published in 1925. Reliance on recent advances in science, but also powerful writing. Eg. Bronchiectasis—“‘Stinking pools of pus’ accumulate to cause ‘exceedingly foul breath which makes a social outcast of the unfortunate victim so that he tends to live a life alone, apart, helpless and hopeless.’”

Sir William Osler (1849-1919)

William Boyd (1885-1979)

Abuses of Pathology

  • Ontological (External) causes in ‘modern’ models of disease—diseases caused by viruses and bacteria.
  • Physiological (Internal) causes in ‘modern’ models—genetic or autoimmune disorders.
  • Disease descriptions in medical textbooks generally conform to organismic view of disease—something undesirable and hopefully discontinuous.
  • But problems and abuses with such views: Ontological view has led societies to reject people who appear to be at risk (Egs. 19th century imigrants who were ‘carriers’ of typhus and cholera, and now with HIV/AIDS equated with Haitians, homosexuals, Africans)
  • Physiological views of disease can allow some to blame the patients for their illnesses: The result is race, gender, class linked to disease—such as diseases of the Jews, Women, or even Poverty.
  • Science can be wrong—phrenology of 19th century—character and intelligence linked to shape of the head.

Map of Diphtheria Cases in New York City, Mid 1800s

Phrenology Diagram Dating From 19th Century

Pathology: Theories & Ideas for the Future?

  • Turning Pathology on Its Head:
  • Not an organismic view, but perhaps the opposite—a population-based view of disease. In this view of the world disease is constant and cannot be eradicated, indeed should not be eradicated and might even be beneficial.
  • This non-organismic or population-based theory is also called the ecological theory of disease. Relates to ideas of the recent past such as Social Darwinian or Malthusian concepts of survival of the fittest.
  • For Canadian society, at a less extreme level, such ideas can be linked to funding issues related to healthcare.
  • ‘Greatest Good for the Greatest Number’. Therefore, perhaps some levels of disease are tolerable?

John Chapman Painting of Pathology, Early 1800s