Let me begin by paraphrasing a daughter's letter to her father, of June 1326:

I haven't wanted to upset you, but I am suffering from an illness of the head that will totally deprive me of sight, though I may be able to tell light from dark. Can you please find someone there who can help me better than the doctors here? They are calling this illness “cataract”, and apparently it can be cured if mine is the right kind, though no one here says it is.

The frightened daughter is the 25-year-old Princess Isabel, wife of Frederick of Austria, writing from Graz to her father James II of Aragon. Her anxious father wrote back immediately, asking her what her doctors said her symptoms were and what they thought had caused the illness, so that he could summon his own medical experts to see if they knew how she could be treated. Unfortunately, as it happened, James himself died the next year, before he could do anything further.

Robert Koch's identification of the tuberculosis pathogen in 1882 is held to be his greatest scientific achievement. In the eyes of his friend and colleague, Friedrich Löffler, the discovery was a “world-shaking event” which resulted in both instant and everlasting fame, turning Koch “overnight into the most successful and outstanding researcher of all times”. Paul Ehrlich, remembering Koch's presentation in Emil du Bois Reymond's Institute for Physiology in Berlin on 24 March 1882, called it “my single greatest scientific experience”. The sensational character of Koch's achievement, which is noted in Löffler's and Ehrlich's retrospective statements, seems to have been obvious to contemporaries of the event. Albert Johne, writing a history of tuberculosis in 1883, found that history had, in a way, come to an end: “resulting from the latest of Koch's publications, the pathogenic aspects of the tubercle question are settled at large”. Koch himself profited from the overwhelming reception by being promoted to the rank of a senior executive officer, Geheimer Regierungsrath, in June 1882. March 24, 1882 thus came to stand for two things: Koch's breakthrough to world fame and a sort of doomsday for tuberculosis. Not surprisingly, the event was held in similar esteem by later biographers: Bernhard Möllers in 1950 called it the “greatest and most important success of his life”, and Thomas Brock, Koch's most recent biographer, assessed the discovery of the tubercle bacillus as the first of two steps on Koch's road to fame in the early 1880s. In conjunction with the 1883–84 cholera expedition, which made Koch a hero for the public, the tubercle bacillus indicated his breakthrough in the scientific world.

On 30 August 1998, the Mail on Sunday, under the headline “TB refugee ‘must be held in hospital’”, described the case of a Somalian man who had been “ordered by a court to remain in hospital for six months to prevent him spreading a highly infectious deadly disease”. That disease was tuberculosis and a court order had been issued “after the man had twice staggered into Northwick Park Hospital in Harrow, North-West London, for treatment but left without trace. He failed to take prescribed treatment and his condition rapidly deteriorated, forcing him to return to hospital a third time.”