The World Health Organization first observed 'World Tuberculosis Day' on this day. The date commemorates the day Koch announced his discovery of the tuberculosis bacterium, raising awareness of the global epidemic of tuberculosis.

Robert Koch died in Baden-Baden at the age of 66, three days after giving a lecture on his tuberculosis research at the Prussian Academy of Sciences. His death marked the end of a pivotal era in the development of bacteriology and medicine.

Koch arrived in German New Guinea as part of an expedition. He examined the Papuan people and their blood samples and noticed they contained Plasmodium parasites, the cause of malaria, but their bouts of malaria were mild or could not even be noticed, i.e. were subclinical. On the contrary, German settlers and Chinese workers, who had been brought to New Guinea, fell sick immediately. The longer they had stayed in the country, however, the more they too seemed to develop a resistance against it.

Koch published his experiments with tuberculin in the Deutsche Medizinische Wochenschrift. An English version was published in The British Medical Journal simultaneously. Koch referred to tuberculin as "brownish, transparent fluid."

Robert Koch isolated Vibrio cholerae in pure culture during his cholera research in Calcutta, India. This was a crucial step in identifying the causative agent of cholera, although its discovery was credited before to Filippo Pacini.

Koch announced his discovery of Mycobacterium tuberculosis, the bacterium causing tuberculosis, to the German Physiological Society in Berlin. This day is now observed as 'World Tuberculosis Day' by the World Health Organization every year since 1982.

Heinrich Hermann Robert Koch was born in Clausthal, Kingdom of Hanover, German Confederation. This marked the beginning of the life of a scientist who would become one of the founders of modern bacteriology.