Charles Jules Henri Nicolle (21 September 1866 – 28 February 1936)[1] was a French bacteriologist who received the Nobel Prize in Medicine for his identification of lice as the transmitter of epidemic typhus.

[2][1] He did just that in 1903, when he became Director of the Pasteur Institute in Tunis and conducted his Nobel Prize-winning work on typhus, bringing Hélène Sparrow with him as laboratory chief.

[6] However, under Nicolle’s guidance over the next 33 years, the 'sister' Institute in Tunis quickly became an international centre of its own for the production of vaccines used against infectious diseases and for medical research.

[3][6] Nicolle’s success in expanding the Pasteur Institute in Tunis lies primarily in his deviation from the traditional Pasteurian ideology that mandated that medical aid and research be done in a nonprofit manner.

[3][6] As Nicolle continued his ongoing research on the disease, he later switched to using guinea pigs as his model organism instead of chimpanzees as they were just as susceptible to infection and were also smaller and cheaper.

[3][6] An important finding from further research showed that the major transmission method was not louse bites but excrement: lice infected with typhus turn red and die after a couple of weeks, but in the meantime, they excrete a large number of microbes.

[3] Nicolle surmised that he could make a simple vaccine by crushing up the lice and mixing it with blood serum from recovered patients.

[6] He was the first to determine that sodium fluoride was a good reagent to sterilize parasites (so that they are no longer infectious) while also preserving their structure (to use in vaccines).