On 6 July 1885, nine-year-old Joseph Meister arrived in Paris after being bitten repeatedly by a dog believed to be rabid. With rabies considered fatal once symptoms appeared, his mother sought help from Louis Pasteur, a chemist who had been testing an experimental treatment in animals.
Pasteur had no medical degree, so the injections were administered by the physician Jacques Joseph Grancher. The Institut Pasteur records that Grancher administered 12 doses over ten days and that, less than a month later, it was clear Meister had survived.
The scientist behind the treatment had begun life far from medicine. Pasteur was born on 27 December 1822 in Dole, in eastern France, to Jean-Joseph Pasteur, a tanner and former soldier.
As a boy, Pasteur was not regarded as an exceptional scholar. He devoted much of his attention to fishing and drawing, and his surviving pastel portraits show that art was more than a passing childhood distraction.
The student who came fifteenth
Pasteur first qualified for the École Normale Supérieure in Paris after finishing fifteenth in its competitive entrance examination. He considered that result inadequate, declined the place and spent another year strengthening his knowledge of the physical sciences.
When he took the examination again, he finished fourth and entered the school in 1843. Science News documents both examination results, as well as the doctorate in physics and chemistry that he completed in 1847.
Crystallography soon became the focus of his work. He was particularly interested in tartaric acid and racemic acid, substances connected to the sediment that forms in wine barrels.
A pair of tweezers and molecular asymmetry
In 1848, at the age of 25, Pasteur examined crystals of a salt derived from racemic acid and noticed that they occurred in two forms. The forms were mirror images of each other, rather like right and left hands.
Using tweezers, he separated the tiny crystals into two groups. After dissolving them separately and passing polarised light through the solutions, he found that one solution rotated the light in one direction while the other rotated it in the opposite direction.
Pasteur had demonstrated a connection between crystal shape, optical activity and molecular asymmetry. His work became foundational to stereochemistry, although the later concept of a tetrahedral carbon atom was developed independently by Jacobus van ’t Hoff and Joseph Le Bel in the 1870s.
From fermentation to germ theory
The path from crystals to microorganisms ran through fermentation. After moving to Lille in 1854, Pasteur investigated problems affecting local alcohol production and argued that fermentation was driven by living microorganisms rather than being only a chemical decomposition.
He found that different microorganisms were associated with different forms of fermentation and spoilage. Controlled heating could kill many of the unwanted organisms without ruining the liquid, leading to the process that became known as pasteurisation.
Pasteur initially applied the method to wine and beer rather than milk. Later adaptations made pasteurisation an important food-safety measure for milk, juice, cream, eggs and other products.
His fermentation experiments also helped overturn belief in spontaneous generation. In his well-known swan-neck flask experiments, sterilised broth remained uncontaminated while airborne particles were prevented from reaching it, strengthening the argument that microorganisms came from the environment.
Pasteur did not originate every element of germ theory, and scientists including Agostino Bassi, Ignaz Semmelweis, John Snow, Joseph Lister and Robert Koch made distinct contributions. Pasteur’s experiments nevertheless helped turn ideas about living agents and disease into a powerful experimental framework.
Silkworms, chicken cholera and anthrax
In the 1860s, Pasteur was asked to investigate diseases devastating the French silk industry. He helped distinguish pébrine from flacherie and developed a practical method of examining adult moths for the corpuscles associated with pébrine, allowing breeders to reject infected eggs.
His interpretation was not immediately complete. Pasteur initially resisted the conclusion that the pébrine corpuscles were parasites, but the screening and selection system developed through his work gave silk producers a practical way to limit transmission.
Pasteur’s laboratory later investigated chicken cholera. The College of Physicians of Philadelphia describes the resulting chicken-cholera vaccine as the first laboratory-developed vaccine, produced using weakened bacteria.
The familiar account says that an assistant failed to inoculate chickens before a holiday and later used an old culture that caused only mild illness. When the recovered birds resisted a fresh virulent culture, Pasteur recognised that a weakened microorganism could produce protection, although historians have questioned how literally the traditional holiday story should be read.
Pasteur’s team then pursued a vaccine against anthrax, a bacterial disease of livestock. Other investigators had already linked rod-shaped organisms to anthrax, and Robert Koch had demonstrated the life cycle of Bacillus anthracis, so Pasteur should not be credited with discovering or first isolating its cause.
Pasteur’s major contribution was vaccine development. At Pouilly-le-Fort in 1881, his team staged a public trial in which vaccinated animals largely survived an anthrax challenge while unvaccinated controls died, turning the experiment into a widely reported demonstration of laboratory vaccination.
The line most often associated with the chicken-cholera episode actually predates it. Pasteur said, Dans les champs de l’observation, le hasard ne favorise que les esprits préparés, in a speech delivered at Douai on 7 December 1854. In English, the phrase is commonly rendered as “In the fields of observation, chance favours only the prepared mind.”
The boy from Alsace
Rabies presented a different challenge because Pasteur could not see or grow its infectious agent using the bacteriological methods available to him. The agent is now known to be a virus, far smaller than the bacteria visible through nineteenth-century microscopes.
Pasteur and his collaborators passed the disease through rabbits and dried infected spinal-cord tissue for different lengths of time. They then used preparations of progressively greater strength in an attempt to produce immunity.
When Joseph Meister’s mother brought him to Paris, Pasteur’s collaborators were divided over using the treatment in a child. Grancher judged that the danger justified the attempt and administered the injections while Pasteur supervised the course.
Meister did not develop rabies. His case brought international attention to the treatment, although the result could not establish with absolute certainty that the dog had transmitted rabies to him.
Patients subsequently travelled to Paris from Europe, Russia, the Americas and North Africa. The demand helped generate the international fundraising campaign that led to the Institut Pasteur, formally inaugurated on 14 November 1888.
The man behind the legend
Pasteur was demanding, ambitious and combative in scientific disputes. Later study of his private notebooks complicated the spotless heroic image promoted during and after his lifetime, particularly around how some vaccine experiments were described publicly.
Those qualifications do not erase his achievements. His unusual ability to connect chemistry, agriculture, microbiology and disease changed laboratory science and helped establish vaccination as a method that could be deliberately developed rather than discovered only through naturally related infections.
His work belonged to a wider nineteenth-century effort to make the causes of disease traceable. John Snow’s investigation of London’s 1854 cholera outbreak, Lister’s antiseptic surgery and Koch’s pathogen research all formed part of that transformation.
The legacy beneath the mosaics
Pasteur died on 28 September 1895 at the age of 72. He was buried in a crypt beneath the Institut Pasteur, where mosaics recall his work on fermentation, silkworm disease, anthrax and rabies.
The molecular asymmetry he studied as a young chemist remains fundamental to pharmaceutical chemistry. Mirror-image versions of the same molecule can behave differently in the body, making control of molecular orientation essential in modern drug development.
July 6 is now observed as World Zoonosis Day, a date recognised in World Health Organization material on diseases that pass between animals and humans. The date commemorates the first widely recognised human use of Pasteur’s rabies vaccine, not the first vaccination connected to an animal disease.
Rabies remains a major public-health problem despite being preventable. The WHO estimates approximately 59,000 deaths from rabies each year, with the greatest burden falling on marginalised populations in Asia and Africa where prompt post-exposure treatment may be inaccessible or unaffordable.
Joseph Meister lived until 1940 and later worked at the Institut Pasteur. Film recorded for the fiftieth anniversary of his treatment preserved the adult face of the boy whose survival turned an experimental course of injections into one of the defining stories of modern medicine.
