In 1894, on a summer morning in Calcutta, the Jewish-Russian scientist Waldemar M. Haffkine dressed formally in a suit and tie went out to vaccinate slum dwellers of the imperial city against cholera. He had built a small workplace nearby where he prepared his vaccines every day. His work started early in the morning when he and his Bengali assistant, Dr. Chowdhury, prepared the vaccines to begin inoculations before sunrise, before the slum dwellers left for their daily labor. Haffkine and his assistant worked in the blazing sun with an umbrella as cover. After a break in the afternoon, they met again in the laboratory to prepare more vaccines for the next round of inoculations and then set out once more for the slums in another part of the city. They remained there, inoculating until late in the night under the light of the chirag (oil lamps) provided by local residents.

In the slums of Calcutta, Haffkine was confronted with life and disease in the tropics. As he vaccinated the slum dwellers with his anticholera vaccines, he found that the lines between the laboratory and the world outside were often blurred. This was a novel experience for the European laboratory scientist: