What the Doctor Ordered

1. What the Doctor Ordered Philosophy and social theory Advances in biological knowledge Advances in data collection and interpretation (Statistics) Advances in instrumentation and medical techniques

2. Modern Medicine • There has not been a really large-scale epidemic since 1918-20 despite our high population density • Modern medicine remarkably effective • Succeeded by reducing patient to disconnected parts, often excluding patient entirely from decision making.

3. The Irony of Early Medicine • Every disease was considered unique • Patient dictated treatment • Sounds very much like what we now call “holistic medicine.” • Only problem: it didn’t work • Why not? Insufficient Knowledge • Body functions imperfectly known • Role of micro-organisms unknown • Case knowledge limited

4. Who’s a Doctor? • Doctor = Latin, “teacher,” someone who had learned subject matter well enough to teach it. • Medicine was late in being added to university curricula • Surgeons weren’t considered doctors until about 1800 • Physicians took the title “doctor” from professors, not the other way round.

5. William Harvey, 1628 • Estimate Volume of blood in heart, say two ounces. • Heart beats 100,000 times a day • That means the heart pumps 200,000 ounces or over 1500 gallons of blood a day. • Clearly ridiculous – hence blood must circulate • One of the earliest examples of “back of the envelope” or “order of magnitude” calculations in science. Use of rough calculation to rule out hypothesis.

6. The French Revolution • Tremendous need for battlefield physicians • Many “Establishment” physicians purged or fled • Country surgeons called into service • Emphasis on what worked, not on theory • Ironically, many shortcuts were more effective than traditional practice • Lots of opportunity to make observations

7. Post-Revolution Medicine • Surgeons were in charge • Hospitals were specialized • Emphasis on observation and practice • Doctors had automatic right to dissect cadavers • Patients had no power to control process or object to treatment • Poor • Soldiers used to taking orders • “My way or the highway” – patients who objected could be discharged

8. Statistics • Probability = (ways event can happen)/(possible outcomes) • One event or another (but not both): add probabilities • One event and another : multiply probabilities • Some outcome has to happen, regardless how low the probability

9. A Few Common Statistical Fallacies • Confusing order and probability • Long runs do not make an event less probable • Long negative runs do not make an event more probable • Spurious patterns • Clusters don’t make events more or less probable. • After-the-fact probabilities • Treating non-random events as chance events • Poor memory and fakery

10. Cholera and its Aftermath • Cholera killed 22,000 in England 1831-33 • Riots and civil disorders sparked by poor living conditions, sparked reforms • William Farr, a government clerk, compiled mortality tables that enabled doctors to identify unusual death rates • Farr noticed that cholera mortality decreased away from the Thames but suspected the stink from the river might be the cause

11. The Birth of Epidemiology • John Snow, 1853, began to suspect cholera was connected to contamination by fecal material. • John Simon, Medical Officer for London, showed in 1855 that contaminated water was the cause. • In 1858 Parliament voted on a massive rebuilding of the sewer system. Cholera stopped and never returned. • Nobody knew, even then, what specifically caused cholera

12. What causes disease? • Rising mortality in hospitals as operations increase • Cholera epidemic of 1830’s • Approaches to contagion • Bad air as cause (malaria from Latin for “bad air”) • Quarantine • Some understanding of cleanliness but insufficient to control disease

13. Louis Pasteur • 1857: Studies fermentation • Agent is alive and reproduces • Agent can travel through air • Food does not spoil if agent excluded • 1864: pasteurization • We finally know why food canning works and how to prevent failures • Link to decay a clue but also a trap

14. Fighting Germs • 1850’s Ignatz Semmelweiss uses antisepsis • 1865: Joseph Lister (son of inventor of achromatic microscope) applies germ concept to surgery, begins using carbolic acid • Identification of Disease Micro-organisms: Now We Know What to Look For • 1876: Robert Koch isolates anthrax bacillus

15. How Disease Survives • Kill the host too quickly, the organism dies out • Pathogen and host evolve to coexist (popular stereotype) • Disease remains lethal but messy, to facilitate spread (cholera, Ebola) • Disease is lethal but has long mild phase (AIDS) or residence in some other vector (Ebola)

16. Why Did These Developments Come So Late In History? The Babylonians could have measured blood pressure or invented the stethoscope, so why did it take so long?

17. Stimuli for invention • Belief that observations could be informative • Belief that observations could lead to good use • Need Access to Body to Interpret Observations • Once progress began in finding causes and cures of diseases, growth of medicine was explosive

18. Poor optics were a real bottleneck • Leeuwenhoek’s microscopes of the 1600’s were astonishingly good, but still magnified barely 100 times. • Details of cell required the achromatic microscope

19. Antisepsis and anesthesia require some fairly advanced chemistry • Alcohol is useful for both purposes but naturally fermented beverages are not alcoholic enough • Distillation discovered by Arabs in Middle Ages • Nitrous oxide, ether, carbolic acid do not occur widely in nature and all require sophisticated chemistry to produce

20. Perpetual War • Some bacteria are one drug away from complete resistance to antibiotics • Disease organisms evolve new defensive and offensive strategies quickly • We will probably always be devising new strategies. So will the microbes. • Conquer, co-opt or coexist? • We are homogenizing the planet on a geologically instantaneous time scale.