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The contributions of Santiago Ramón y Cajal in the field of microbiology went unnoticed, but in a study motivated by a cholera epidemic he laid the foundations for vaccines based on inactivated bacteria.
An epidemic also made Santiago Ramón y Cajal temporarily reorient his research, as so many scientists have done now. In 1885, a cholera epidemic broke out in Valencia – where Cajal had just arrived as professor of Anatomy – which later spread to much of Spain, with devastating effects on the population.
Not without controversy, bacteriologist Jaime Ferrán began to apply a vaccine of his invention, a subcutaneous injection of live cholera bacteria. When the epidemic spread to Aragon, Cajal was commissioned by the Provincial Council of Zaragoza to issue an opinion on the causes of the epidemic and the validity of the Ferrán vaccine. Cajal spent that summer of 1885 experimenting alone on the outskirts of Zaragoza.
In addition to reaching the conclusion that Ferrán's vaccine could even be dangerous - which alienated them forever - he made a singular discovery: "The experimental proof of the chemical vaccine, that is, of the possibility of preserving animals of the toxic effects of the most virulent virgula, injecting them beforehand, via the hypodermic route, with a certain quantity of crops killed by the heat", explained in his own words in 'Memories of my life'.
Although "the work of Santiago Ramón y Cajal in the field of microbiology went unnoticed," says Unizar microbiologist Jesús Gonzalo, "the truth is that he laid the foundations for what would be a vaccine based on inactivated bacteria." As his 1885 works were not published beyond the national scope, "the American scientists Daniel Elmer Salmon and Theobald Smith are recognized worldwide as precursors of vaccination with inactivated microorganisms thanks to a work published in 1886."
But Cajal recognizes that "if my work lacked echo in the laboratories of Paris and Berlin (...), it was worth, however, a material and spiritual award" that he especially valued. In gratitude for his studies on the cholera microbe, the Zaragoza council "gave him a magnificent Zeiss microscope, 'the last word in magnifying optics' - says researcher Carlos Martín -, of great importance for his research career in neuroscience." .
