HSCI 408 Germ Theory

What nickname does the lecture give the Black Plague?

"The mother of all plagues"

What two kinds of medieval trade routes carried plague?

Overland routes (caravanserais) and maritime (sea) routes

What was a caravanserai, and why does it matter for plague?

A stop along overland trade routes where merchants, animals and goods came together. The same networks that carried trade helped plague spread.

When did the Black Death sweep across Europe (per the lecture map)?

1347–1352

Who introduced quarantine, and when?

Ragusa, in 1377 ("the birthplace of quarantine")

Why did Ragusa introduce quarantine?

A desperate effort to stop plague

What were pest houses?

Houses communities set up to isolate and care for the sick. Early forerunners of smallpox and fever hospitals (e.g. Odiham Pest House).

What did Avicenna (The Canon of Medicine, c. 1025) discuss?

Contagion, centuries before microbes could be seen

What is miasma theory?

The idea that disease is caused by "bad air". Many European physicians kept explaining epidemics this way.

What did Fracastoro propose (On Contagion, 1546)?

Tiny "seeds" of contagion spread disease through direct contact, contaminated objects, or transmission at a distance

Who was Athanasius Kircher (1602–1680)?

Author of a physico-medical examination of contagious plague (Rome, 1657). Another early contagion thinker.

What did Eyam (1666) do during plague?

Residents isolated their village to protect neighbouring communities. Supplies crossed the boundary, people stayed.

What is the Richard Lanpheare slide about?

Lanphear's 8th great-grandfather. His will (Aug 12, 1665) says he wanted to settle his estate "by reason of these contagious tymes". Shows the Great Pit in Aldgate.

What were the Bills of Mortality?

Weekly counts of burials and causes of death in London, started to count plague victims

When did the Bills of Mortality become a regular system of public surveillance?

1603

What is the progression of death recording in the lecture?

Bills of Mortality → death certificates → National Death Index (recording individual deaths)

What does the 1665–66 London plague chart compare?

Weekly deaths from all causes (solid line) vs deaths attributed to plague (broken line)

What is public health surveillance (as used in this lecture)?

Systematically counting and reporting deaths and disease so outbreaks can be detected and a response organized

What phrase describes childbed fever in the lecture?

"The Most Unspeakable Terror"

What did Alexander Gordon (Aberdeen) admit?

That he was the means of carrying the disease (puerperal fever) to a great number of women

Why was erysipelas an important clue for childbed fever?

Gordon saw erysipelas alongside childbed fever. It showed infection could travel with the caregiver.

What did Oliver Wendell Holmes argue (before germ theory was established)?

That physicians could carry childbed fever from one patient to another

Describe Charles Knowlton's 1844 case.

After treating a 15-year-old boy with erysipelas, he attended a woman having a miscarriage, emptied her uterus by hand without washing his hands, and she died. He asked if he had carried the infection between them.

Where and when did Semmelweis's intervention take place?

Vienna General Hospital (First Maternity Clinic); chlorinated-lime handwashing began in May 1847

How long after the intervention did Semmelweis's book come out?

Fourteen years later

What was the physicians vs midwives pattern in Vienna?

Higher maternal mortality in the physicians' division (peak ~16% in 1842) than the midwives' (~7.5%). After handwashing the two converged by 1848.

Vienna lying-in maternal mortality before vs after routine teaching autopsies?

12.5 per 1,000 (1784–1822) → 62.4 per 1,000 (1823–1847)

Who opposed contagion and blamed childbed fever on "accident, or Providence"?

Charles D. Meigs

How many cholera deaths were there in England in 1849 (per the diagram)?

About 52,000 cholera deaths (plus ~18,900 diarrhoea deaths)

What did Edwin Chadwick argue about disease?

When circumstances are removed by drainage, cleansing, better ventilation and similar means, the frequency and intensity of the disease drops

Why did William Farr initially support miasma?

Cholera deaths declined with elevation above the Thames. The pattern looked like bad air, not contaminated water.

What is the lesson of the Farr slide?

A convincing pattern can support the wrong explanation

What did John Snow propose in 1849?

That cholera spreads through contaminated water (five years before the Broad Street outbreak). On the Mode of Communication of Cholera.

What did Snow's water company comparison show? (deaths per 1,000)

1848–49: Lambeth 12.5 vs Southwark & Vauxhall 11.8. 1853–54 (after Lambeth moved its source): Lambeth 3.7 vs Southwark & Vauxhall 13.0.

Why did Snow call it an experiment "on the grandest scale"?

~300,000 people of every rank were split into two groups without their choice or knowledge: one drank sewage-contaminated water, the other mostly clean water

How did flushing (water closets) magnify London's crisis?

Sewage left homes but not London: drains emptied into the Thames, where water companies also drew drinking water. One household's waste could come back through another's tap.

How much faecal matter entered the Thames daily in 1857?

~250 tons (about 50 elephants)

What did the 1857 law require about Thames water intakes?

Drinking-water intakes had to be above Teddington

Why did guano replace human waste as fertilizer?

As London grew, hauling human waste to farms got too costly. Concentrated, imported guano took its place.

What did Joseph Bazalgette build, and when?

London's sewer system, 1859–1875: ~82 miles of main intercepting sewers and 1,100+ miles of street sewers, carrying sewage downstream away from central London

Where was London's 1866 cholera epidemic concentrated?

East End neighbourhoods supplied by the Old Ford reservoir (it followed the contaminated water supply)

Big takeaway of the cholera section?

People recognized contagion and organized prevention centuries before they understood microbes

What is the key message of the "Golden Age of Bacteriology" slide?

We celebrate the breakthrough, but the evidence accumulated over decades (many scientists, not one)

What was Jacob Henle's contagion theory?

Before microscopic forms can be regarded as the cause of contagion, they must constantly be found in contagious material, be isolated from it, and have their strength tested

What did Pasteur's swan-neck flask experiment show?

Broth stayed sterile until it touched the trapped dust and microbes. Microbes come from contamination, not spontaneous generation. Basis for sterilization and antisepsis.

What did William Budd say about TB?

"Tuberculous matter" is the morbific (disease-causing) matter, by which phthisis (TB) spreads from person to person and through society

What did Joseph Lister do, and what were the results?

Used carbolic acid in surgery (principle 1867, results 1870). Amputation deaths: 16/35 (46%) before → 6/40 (15%) after.

Who first saw "animalcules"?

Anthonie van Leeuwenhoek (1632–1723), with a single-lens microscope

Who named "cells", and how?

Robert Hooke (Micrographia, 1665). Cork's tiny compartments reminded him of monks' small rooms (cells).

What did Theodor Schwann state?

All living things are composed of cells

What did Rudolf Virchow argue (cell theory)?

Disease is caused by changes in cells or their destruction from outside forces or agents (cellular pathology)

What is the lecture's point about cell theory?

Where disease occurs is not the same as what causes it. Microbes, toxic chemicals and other agents can trigger cellular changes.

What is Tyndall's germ box?

One of the "tools of the trade" of bacteriology (John Tyndall)

Who developed the Gram stain?

Hans Gram

What did Paul Ehrlich's method make visible?

Tuberculosis: Mycobacterium tuberculosis as acid-fast bacilli

Who supplied the growth medium and who the dish for growing microbes?

Fanny Hesse supplied the medium; Julius Petri supplied the dish (Petri dish)

What did Jean-Antoine Villemin ask/show about TB?

Whether tuberculosis could be transmitted (he studied TB transmission before Koch)

What happened in 1882?

Robert Koch announced the cause of tuberculosis, bringing earlier ideas together

What did germ theory claim?

Specific microorganisms can cause specific diseases and spread through identifiable pathways

Seeing a microbe vs demonstrating a cause?

Seeing = "this organism is present" (a clue). Demonstrating = "this organism causes this disease" (needs experiments).

Henle–Koch postulate 1

The microbe must be found in abundance in all organisms suffering from the disease, but not in healthy organisms

Henle–Koch postulate 2

The microbe must be isolated from a diseased organism and grown in pure culture

Henle–Koch postulate 3

The cultured microbe should cause disease when introduced into a healthy organism

Henle–Koch postulate 4

The microbe must be re-isolated from the experimental host and identified as identical to the original causative agent

What is the "Koch's Legacy?" point?

Koch synthesized the evidence and championed germ theory, but the Golden Age grew from decades of work by many scientists

Who discovered the anthrax bacillus (1877), TB (1882) and cholera (1883) bacteria?

Robert Koch

Who discovered the gonorrhea bacterium (1879) and the typhoid bacterium (1880)?

Gonorrhea: Neisser. Typhoid (Salmonella typhi): Eberth

Who discovered the diphtheria bacterium (1883)?

Klebs and Loeffler (Corynebacterium diphtheriae)

Who discovered the plague bacterium (Yersinia pestis, 1894)?

Kitasato and Yersin (independently)

Who discovered the whooping cough bacterium (1906)?

Bordet and Gengou (Bordetella pertussis)

What was Koch's tuberculin (1890)?

A premature promise of a TB cure ("A cure for consumption?")

What was Hermann Biggs's role?

General Medical Officer, NYC Department of Health

What did the 1889 NYC "Contagious Consumption" report say?

Pulmonary TB (consumption) is directly passed from person to person through germs in expectoration (sputum). It gave rules to prevent its spread (e.g. don't let sick people spit on floors, wash utensils, avoid carpets).

What public health tools did the NYC Health Dept. develop in the early 1900s?

Public labs, diphtheria antitoxin, and serums (even supplied to the US Army in 1917 for pneumonia, meningitis and dysentery)

What is the carrier state?

Healthy people can spread disease without symptoms

Who was Mary Mallon?

A cook who carried typhoid (Salmonella Typhi) without symptoms. Held on North Brother Island. Soper traced the outbreaks (1907); Park reported on carriers (1908). The bacteria can persist in the gallbladder and pass into stool.

What was William H. Park's manual?

A practical manual on pathogenic micro-organisms for students, physicians and health officers

What are the four ways they tested their explanations?

Observe (physicians vs midwives), Compare (cholera by water supply), Intervene (handwashing), Experiment (inoculation reproduced anthrax)

How did discovery become public protection?

Public laboratories (identify and test), disease reporting (detect outbreaks and respond), diagnostic services (reliable testing), access to prevention and treatment (vaccines, antitoxins, care)

What is the lecture's line about discovery and protection?

Discovery mattered when protection reached people

What was Paul Starr's point about public health power?

Public health helped establish the authority of scientific medicine, but as private practice gained power, prevention and treatment became institutionally divided and public health's broader environmental mission narrowed

Final summary of the Germ Theory lecture?

Microbes cause specific diseases and spread through people, water, food and objects. Patterns of disease and experiments revealed transmission, often before the microbe was identified. Germ theory ushered in the Golden Age of Bacteriology and a scientific revolution in medicine.