18th-19th Century Medicine: Jenner, Pasteur, Koch, and Public Health
18th-19th Century Medicine: Jenner, Pasteur, Koch, and Public Health
The 18th and 19th centuries saw a revolution in medical understanding. The discovery of vaccination, the development of germ theory, and major improvements in public health transformed medicine from a practice based on ancient ideas into a modern science.
Edward Jenner and Vaccination (1796)
Edward Jenner (1749-1823) was a country doctor in Gloucestershire who made one of the most important discoveries in medical history:
- Jenner observed that milkmaids who caught cowpox (a mild disease) seemed to be protected against smallpox (which killed around 400,000 Europeans every year and left survivors scarred and often blind).
- In May 1796, Jenner took pus from a cowpox blister on milkmaid Sarah Nelmes and scratched it into the arm of James Phipps, an 8-year-old boy.
- Six weeks later, Jenner deliberately exposed Phipps to smallpox. The boy did not develop the disease — he was immune.
- Jenner published his findings in 1798 and called the process "vaccination" (from "vacca," Latin for cow).
Opposition:
- Many doctors opposed Jenner — he could not explain why vaccination worked (germ theory had not been developed).
- The Royal Society rejected his initial paper.
- Anti-vaccination campaigners objected on religious grounds (using animal material was "unnatural") and feared side effects.
- Some doctors opposed it because inoculation (a less safe earlier method) was profitable.
Impact:
- The British government made vaccination free in 1840 and compulsory for infants in 1853.
- Smallpox deaths fell dramatically. The disease was eventually eradicated worldwide in 1980 — the only human disease to be completely wiped out.
- However, Jenner's method only worked for smallpox — he could not create vaccines for other diseases because he did not understand the underlying science.
Louis Pasteur and Germ Theory (1861)
Louis Pasteur (1822-1895), a French chemist, made the breakthrough that explained why people got sick:
- In 1861, Pasteur published his Germ Theory of Disease, proving that microorganisms (germs/bacteria) caused decay and disease — not the other way around (the old "spontaneous generation" theory).
- Pasteur's famous swan-neck flask experiment proved that germs came from the air, not from the liquid itself. Broth in sealed flasks stayed fresh; broth exposed to air went off.
- Pasteur developed vaccines for chicken cholera (1879), anthrax (1881), and rabies (1885) by using weakened forms of the disease-causing microorganism.
- He also developed pasteurisation — heating liquids to kill bacteria (still used for milk today).
Robert Koch (1843-1910)
Robert Koch, a German doctor, built on Pasteur's work by identifying specific germs that caused specific diseases:
| Year | Discovery |
|---|---|
| 1876 | Identified the bacterium causing anthrax |
| 1882 | Identified the bacterium causing tuberculosis (TB) |
| 1883 | Identified the bacterium causing cholera |
- Koch developed techniques for growing bacteria on agar plates, staining them with dyes, and photographing them through microscopes.
- His work enabled other scientists to identify the germs responsible for many diseases (typhoid, diphtheria, plague, tetanus) — by 1900, 21 disease-causing germs had been identified.
Florence Nightingale and John Snow
Florence Nightingale (1820-1910)
- Nightingale transformed nursing from a disreputable occupation into a respected profession.
- During the Crimean War (1854-56), she improved conditions at the Scutari hospital, reducing the death rate from 42% to 2% through cleanliness, sanitation, nutrition, and fresh air.
- In 1860, she opened the Nightingale Training School for Nurses at St Thomas' Hospital, London.
- She used statistics (pie charts and graphs) to persuade the government to improve military and hospital conditions.
- Her book Notes on Nursing (1859) was widely influential.
John Snow and Cholera (1854)
- Cholera killed tens of thousands in London (epidemics in 1831, 1848-49, 1854, 1866).
- In 1854, Dr John Snow mapped cholera deaths in the Broad Street area of Soho, London. He proved that the outbreak centred on a water pump whose water was contaminated by a nearby cesspit.
- Snow persuaded the authorities to remove the pump handle, and the outbreak subsided.
- Snow proved that cholera was spread by contaminated water, not miasma — but he could not identify the specific germ (Koch did this in 1883).
Public Health Reforms
The 19th century saw major government action on public health:
- Public Health Act 1848 — Set up a General Board of Health; allowed (but did not require) local boards of health. Largely ineffective because it was not compulsory.
- The Great Stink (1858) — Hot weather made the sewage-polluted River Thames stink so badly that Parliament (right next to the river) could not sit. This forced action.
- Joseph Bazalgette — Engineer who designed London's modern sewer system (1859-65): 1,100 miles of street sewers feeding into 82 miles of main sewers. This dramatically reduced cholera and other waterborne diseases.
- Public Health Act 1875 — Made it compulsory for local authorities to provide clean water, sewers, street cleaning, and appoint Medical Officers of Health.
Key Exam Points
- Know the chain of discovery: Jenner (vaccination) → Pasteur (germ theory) → Koch (specific germs) → public health reform.
- Be prepared to evaluate the relative importance of individuals versus government action in improving health.
- Understand the link between scientific discovery and practical change — there was often a significant time lag.