The enigma of Pacini’s Vibrio cholerae discovery

During the 1854 cholera outbreak in Florence, Italy, Filippo Pacini documented that the cause of the infection was a bacterium. This conclusion was also independently reached by John Snow during the 1854 cholera outbreak in London. By using an epidemiological method, Snow found that the infection spread through a polluted water network. Snow identified a water pump as the source of the disease. After removing the infected handle of this pump, the cases of cholera rapidly began to decrease. A microscopic examination of the water showed organic impurities but no bacteria. This discovery was ignored during Snow’s lifetime. In contrast, through microscopy during the autopsies of cholera victims, Pacini observed that the disruption of their intestinal mucosa was closely associated with millions of the bacteria that he called Vibrio cholerae . Via histological techniques, Pacini detected that intestinal mucosa reabsorption dysfunction was the cause of debilitating diarrhoea, vomiting, severe dehydration and death. Nevertheless, his discovery of Vibrio cholerae was ignored during Pacini’s lifetime. A survey of Pacini’s autographic manuscripts suggests that Pacini and Snow may have shared mutual knowledge within their respective seminal papers. This survey also facilitates, for the first time, the creation of maps that illustrate the worldwide distribution of Pacini’s cholera papers from 1854 to 1881. The consistent neglect of Pacini’s discovery remains a true enigma.