DISCOVERY 



147 



now only an occasional instance is seen, in London or 

 Liverpool, imported from abroad. 



Yet in ancient times the disease was very prevalent. 

 It flourished in the thirteenth centun,', when there were 

 said to be over 2,000 lazarettos in France. Robert 

 Bruce died of it in 1329. E.xperts tell us that there is 

 no doubt that the disease called leprosy in the Middle 

 Ages was the same as that known by this name at the 

 present time — though, doubtless, other conditions were 

 often confused with it. There can therefore be no 

 doubt that a dreadful disease, which was once quite 

 common here, has, in these islands at least, become 

 extinct. Will tuberculosis go the same way — tuber- 

 culosis, which causes more deaths in temperate climes 

 than any other infectious disease, and whose economic 

 importance is enormously enhanced by the fact that 

 it carries off so many of its victims in the prime of Ufe ? 

 Will tuberculosis become extinct like leprosy ? 



This is no idle speculation ; for already the death- 

 rate from tuberculosis has declined so remarkably that 

 it is now considerably less than half what it was in 

 the middle of the last century. 



But, it may be asked, can we really be sure of this ? 

 Are the figures to be trusted to the extent that we 

 can safely compare our present returns with those of 

 sixty or seventy j-ears ago ? Are the death-certificates 

 of those days, on which of course the official figures 

 arc based, sufficiently accurate ? May not deaths due 

 to bronchitis or pneumonia have got put down to 

 phthisis, consumption, or pulmonary tuberculosis (they 

 are all one) ? And do not such errors depend on 

 ignorance, prejudice, or even custom ? May it not 

 also fairly be claimed that medical knowledge has made 

 immense strides since those days, and that prejudice 

 and custom, though no doubt still %vith us, do not take 

 the same forms that they did ? Are the statistics of 

 to-day, then, really comparable with those of a bygone 

 era ? To put the objection concisely, it might perhaps 

 be urged that in those more ignorant times of which 

 we are speaking there was a tendency to put down 

 every complaint of the lungs, and indeed of the bowels 

 too, to consumption ; and that the decline in the 

 recorded death-rate from that cause has been due 

 merely to continuous improvement in diagnosis. If 

 this is so, the changes which we claim to be evidence 

 of the dying out of tuberculosis are only changes of 

 name. The deaths occur just the same, but are 

 assigned to another cause. 



This is a serious difficulty, and one not lightly to be 

 dismissed ; but it is too technical to be discussed here, 

 and it must suffice to say that it has received careful 

 consideration from a number of good authorities, and 

 that there is substantial agreement- in the conclusion 

 that, while increase of medical knowledge and changes 



of nomenclature and custom have, doubtless, greatly 

 influenced the figures, yet the errors have to some con- 

 siderable extent cancelled one another (e.g. when causes 

 of bronchitis were attributed falsely to consumption, 

 cases of consumption also were falsely attributed to 

 bronchitis), and that, on the whole, and especially for 

 such large changes as we are now considering, the 

 figures are to be depended on. 



Let us, then, accept the figures as substantially 

 accurate, and pass on to consider what they tell us. 

 Prior to the middle of last centurj' the records, such 

 as they are, are very imperfect. It was not until 1871 

 that it became compulsory for medical practitioners 

 to gi\'e certificates of the cause of death of every 

 patient dying under their care. Before this the majority 

 of deaths were certified, but as late as 187 1, 8 per 

 cent, of the total deaths lacked medical certificates. 

 In 1904 the deficit had fallen to 1-4 per cent. 



We will begin, then, with 1865, about which time the 

 deaths attributed annually to tuberculosis began to 

 show a decided decline. In that year these deaths 

 numbered over 69,000. In 1913, the lowest year on 

 record, they numbered 49,476. There had therefore 

 taken place, in the space of about fifty years, a decline 

 of 20,000 deaths from tuberculosis p)er annum, or 

 29 per cent, of the total in 1865. 



In the meantime the population had increased by 

 nearly 70 per cent., and the death-rate (or ratio of deaths 

 to population) from tuberculosis had fallen from 3,300 

 per mUlion to 1,340 per million, a decline of nearly 

 60 per cent. 



A decline of this magnitude is an immense achieve- 

 ment, even if we have to take off something for the 

 reasons which we have been discussing. If we can 

 accomplish as much in the next half century as has 

 been accompUshed in the last one, tuberculosis will not 

 only have been ousted from its supreme position as 

 the most fatal of all diseases of civilised lands, but will 

 have sunk to the level of those of secondary importance. 

 Nay, more : let the curve which the declining mortality 

 has followed in the past be prolonged, and it will cut 

 the base-line before the end of the century, and tuber- 

 culosis will have become e.xtinct. But stop a moment. 

 Is this really so ? What sort of a curve is it ? It 

 appears to be a straight fine ; but is it really so ? Let 

 us examine it more closely. 



In the chart published by the Registrar-General, 

 giving the annual mortality from tuberculosis since 

 1850, various irregularities occur from year to year. 

 These are due to such causes as unfavourable seasons, 

 epidemics of influenza, scarcity of food, etc., which 

 bring about the deaths of tuberculous persons earlier 

 than they would otherwise occur, and so cause them 

 to fall into one year rather than into the next, to 

 which, under perfectly uniform conditions, they would 



