Robert Koch discovers the cholera bacillus

Background. The fifth cholera pandemic (1881–1896) was a major international outbreak. In 1883, cholera reached Egypt, causing tens of thousands of deaths. The British administration's anti-contagionist policies hindered effective measures. French and German bacteriologists were sent to Alexandria to study the disease and determine its cause.

Investigation in Egypt. In August 1883, the German government sent a medical team led by Robert Koch to Alexandria, Egypt, to investigate the cholera epidemic. This mission was part of the broader scientific effort to determine the cause of the disease during the pandemic.

Discovery and Isolation. Koch isolated the bacterium in pure culture on 7 January 1884. This discovery confirmed the bacterium as the cause of cholera. An Italian bacteriologist later noted that Koch's bacterium was the same as that previously described by Pacini.