During the entire nineteenth century, the scourge of tuberculosis was widely felt and widely feared through all levels of society. Tuberculosis has an ancient history, and in its dominant respiratory form, which primarily affects those in the prime of life, has had an incalculable effect on human societies and individual destinies. It is an infectious disease, although this was not accepted in England until the end of the nineteenth century. Like typhus, its incidence is closely related to environment and domestic habit; like typhus, it too declined during this century, but this decline was far less dramatic, and in all its forms tuberculosis was still the leading killer, after heart disease.
In the decline of tuberculosis, however, may lie the clue to the nineteenth century mortality decline, and the heart of a puzzle which has fascinated many historians. It was identified by Thomas McKeown as the central feature of the mortality decline and, because McKeown considered the decline of tuberculosis to have begun before the effect of the nineteenth-century sanitary reform movement began to be felt, as a prime indicator that the general mortality decline was initiated by rising standards of living. While scholars have subsequently deliberated on the respective influences of housing and nutrition in tuberculosis mortality.
Tuberculosis is a chronic infectious disease which may manifest itself in different forms: as respiratory (pulmonary) tuberculosis (also known as phthisis, or consumption), scrofula, and lupus, tuberculosis of the bones and joints, or tubercular meningitis. In addition to being chronic (the period from the active manifestation of the disease to its termination in death lasts for years rather than weeks or months), it is a cruelly debilitating disease with a most complex etiology. It is caused by the bacillus Mycobacterium tuberculosis, discovered by Robert Koch in 1882, but there are five types of tuberculosis affecting different animal types, of which only two, the human and bovine, cause disease in man.....................
