Scientific discoveries can emerge from the strangest places. In early 1900s France, the doctor Albert Calmette and the veterinarian Camille Guérin aimed to discover how bovine tuberculosis was transmitted. To do so, they first had to find a way of cultivating the bacteria. Sliced potatoes – cooked with ox bile and glycerine – proved to be the perfect medium.
As the bacteria grew, however, Calmette and Guérin were surprised to find that each generation lost some of its virulence. Animals infected with the microbe (grown through many generations of their culture) no longer became sick but were protected from wild TB. In 1921, the pair tested this potential vaccine on their first human patient – a baby whose mother had just died of the disease. It worked, and the result was the Bacille Calmette-Guérin (BCG) vaccine that has saved millions of lives.
