On Jan. 9, 2014, DNA was isolated from a 165-year-old intestine of a cholera victim from Philadelphia –  the first from a nineteenth-century strain of Vibrio cholerae.

In 1849, A deadly cholera outbreak hit Philadelphia and other Eastern seaboard cities. About 1,000 city’s residents died from cholera that year, a figure that would be higher were it not for a program to wash city streets with clean water.

The genome shows that most cholera strains in circulation today, known as El Tor, are genetically distinct from the ‘classical’ cholera that plagued European and North American cities in the nineteenth century, and was responsible for the 1849 outbreak in Philadelphia. (It would be five more years before the British physician John Snow showed that London’s cholera was caused by water contaminated with faecal matter.)