Decomposition of vaccines in a tropical climate was an important concern for colonial bacteriologists. This apprehension coexisted with a fear of the virulence of viruses in the tropics. In studying a particular vaccine research program over three decades, this chapter shows how these two fears shaped laboratory research in British India. The development of the Semple antirabic vaccine was a unique but little known research program undertaken in colonial India between 1910 and 1935. Originally developed by David Semple at the CRI in Kasauli in 1911, it was the most commonly used antirabic vaccine throughout the world in the twentieth century. Until 2000 it was the main rabies vaccine used in developing countries, where rabies is widespread.

Rabies is an acute encephalitis caused by a virus that kills by attacking the central nervous system. Rabies was also the disease in which Pasteurian science made early and crucial breakthroughs. In 1885, Pasteur identified the nervous system as the main target for the experimental reproduction of the rabies virus. He and his collaborators attenuated the virus by repeated passages through rabbits. Strips of fresh spinal cord material taken from rabbits that had died from rabies were exposed to dry, sterile air for various lengths of time. This tissue was then ground up and suspended in a sterilized broth. This solution was used as a vaccine. The vaccine was premised on the Pasteurian principle of using live attenuated vaccines.