From the war years on, Nicolle enjoyed a steady stream of scientific visitors to his colonial institute. Members of the parasitology lab of the Faculté de Médecine de Paris—one of his favored providers of new collaborators—frequently came to Tunis to conduct research. In 1923, he welcomed Dr. Salvadore Mazza, Professor of Microbiology at the Faculty of Medicine of Buenos Aires; two years later, Mazza played gracious host to Nicolle during his mission to Argentina. Yet another of Nicolle's frequent visitors was John Reenstierna. A professor at the Faculty of Medicine in Stockholm, Reenstierna initially came to the IPT in late 1922 as part of a mission for the Swedish government. He returned the following summer and again in 1926: the year he paid tribute to Nicolle at the Journées Médicales. Apparently, Reenstierna's public praise was backed up with private activism. It can hardly be a coincidence that Nicolle first found himself in the running for a Nobel Prize in the autumn of 1923. He wrote to Vallery-Radot:

Though the 1923 run for the Nobel was to prove unsuccessful, Reenstierna's efforts on Nicolle's behalf offer a striking example of the kinds of networks that the director-isolé managed to create between his Tunisian institute and the rest of the medico-scientific world.