The Fight Against Disease

Prior to the 1860s, medical beliefs about the causes of disease were rooted in ancient theories, such as the miasma theory, which suggested that disease was caused by 'bad air.' However, the discoveries of Louis Pasteur and Robert Koch would completely transform the understanding of disease, leading to revolutionary changes in medicine.

Spontaneous Generation

In the late 17th century, doctors recognised the existence of microorganisms, or germs, but they did not believe that these germs were responsible for causing diseases. Instead, the prevailing theory was spontaneous generation, which held that microorganisms spontaneously appeared in decaying matter or in areas affected by illness. According to this theory, germs were considered a result of disease rather than its cause. This misunderstanding hindered progress in understanding how infections spread and how diseases could be prevented or treated.

Louis Pasteur’s Contributions

Louis Pasteur, a French chemist, played a pivotal role in revolutionising medical science. In the 1850s, Pasteur was asked by a French winemaker to investigate why their wine was spoiling. By using a microscope, he discovered that the spoilage was due to bacteria, a type of microbe. Pasteur believed these bacteria were responsible for the degradation of the wine, and by heating the wine to a specific temperature, he successfully killed the bacteria, a process that later became known as pasteurisation.

Building on this, Pasteur conducted further experiments to support his theory. He used two swan neck flasks, filled with broth, which he boiled to kill any existing microbes. He left one flask sealed and broke the neck off the other, exposing it to air. Over time, the open flask became contaminated with microbes from the air, whereas the sealed flask remained uncontaminated. This experiment demonstrated that microbes were present in the air and could cause disease when they entered the human body, laying the foundation for Pasteur's germ theory.

In 1861, Pasteur published his findings on germ theory, a groundbreaking moment that had far-reaching implications for medicine. It paved the way for significant advances in the development of vaccines, the improvement of surgical techniques, and the discovery of antibiotics.

Robert Koch and His Discoveries

Robert Koch, a German doctor, made equally groundbreaking contributions to the fight against disease. Using industrial dyes, Koch was able to stain bacteria, making them easier to identify under a microscope. In 1876, Koch identified the bacterium responsible for anthrax, marking the first time that the specific germ causing a disease was isolated. This was a crucial development because identifying the bacteria responsible for specific diseases allowed scientists to work towards developing targeted treatments and vaccines.

Although Pasteur and Koch were rivals, their work in the late 19th century contributed immensely to the advancement of medicine. Their discoveries were complementary and formed the basis for modern microbiology and infectious disease control.

The Chicken Cholera Vaccine

In 1879, Pasteur, along with his assistant Charles Chamberland, was working on finding a cure for chicken cholera. As part of their research, they were injecting chickens with cholera germs and then trying to treat them. Upon returning from a holiday, Chamberland accidentally injected a chicken with cholera germs that had been left unrefrigerated. Surprisingly, the chicken did not fall ill. Pasteur instructed Chamberland to repeat the process with fresh germs, but again, the chicken remained unaffected.

This led Pasteur to a key realisation: the germs that had been left to deteriorate had caused the chicken to develop immunity to cholera without making it ill. This accidental discovery marked the development of the first vaccine. Unlike Edward Jenner, who had developed the smallpox vaccine without understanding why it worked, Pasteur understood the science behind his vaccine, which allowed him to replicate the process for other diseases, such as anthrax and rabies.

How the Fight Against Disease Developed

The 19th century saw a series of pivotal moments in the battle against disease, driven by the work of Pasteur and Koch. Key developments in medicine, such as the discovery of vaccines, antiseptics, and antibiotics, all stemmed from their pioneering research into the causes and prevention of disease.

Factors that Helped Pasteur and Koch’s Work

Pasteur and Koch’s successes were not solely down to their brilliance; they were also aided by a few important factors:

Technology: Koch’s assistant, Julius Richard Petri, invented the Petri dish, a shallow dish used to culture bacteria. This invention allowed Koch to grow bacteria more efficiently and, combined with the use of industrial dyes, enabled him to identify bacteria more easily using microscopes.

Chance: Pasteur’s discovery of the chicken cholera vaccine was a result of a fortunate accident. The cholera germs left unrefrigerated by Chamberland had weakened, which led to the development of immunity in the chickens. This serendipitous moment paved the way for Pasteur’s future vaccine work.

War: The Franco-Prussian War (1870–1871) spurred a rivalry between Pasteur and Koch, with both the French and German governments funding their research to showcase national pride and scientific superiority. This competition drove both men to further their research and make significant breakthroughs.

Key Individuals: The achievements of Pasteur and Koch would not have been possible without their dedication and scientific curiosity. Their ability to observe, experiment, and build on their discoveries was crucial to the development of new medical methods and treatments.

By the end of the 19th century, the understanding of disease had radically changed. Pasteur and Koch’s work laid the groundwork for modern medicine, significantly improving public health and saving countless lives. Their discoveries marked the beginning of the end for the ancient theories of disease, such as miasma, and ushered in a new era of scientific progress and innovation in the fight against illness.