NATURE 



301 



T' 



THURSDAY, DECEMBER 20, 1917. 



THE TUBERCULOSIS PROBLEM. 

 The Causes of Tuberculosis, together with Some 

 Account of the Prevalence and Distribution of 

 the Disease. By Dr. Louis Cobbett. (Cam- 

 bridge Public Health Series.) Pp. xvi + 707. 

 (Cambridge : At the University Press, 1917.) 

 Price 215. net. 

 HE physician, the teacher, the administrator, 

 or the member of the Public Health and 

 Hyg^iene Committee, though he has had at his 

 disposal innumerable text-books, papers, pam- 

 phlets, reports of Commissions, Blue Books, and 

 the like, has up to the present had access to no 

 well-digfested account of the cause, course, and 

 prevention of tuberculosis, a subject of vital im- 

 portance to the community. 



In writing- a log:ical and well-balanced account of 

 the observations and opinions of others, vitalised 

 by an interu^eaving of the results of his own wide 

 reading and personal investigation, Dr. Cobbett 

 has done much to fill this gap. 



After servingf as one of the scientific investi- 

 gators to the Royal Commission on Tuber- 

 culosis, Dr. Cobbett evidently extended his experi- 

 ence of the pathology of tubercular phthisis in a 

 large industrial centre;, Sheffield, where this occu- 

 pational disease is one of the main factors in the 

 morbidity and mortality bill of the town. He had 

 thus an almost unique training, of which we now 

 reap the fruits. His experience of experimental 

 work and its pitfalls, and his acquaintance with the 

 difficulties that face the practical sanitarian and 

 those who. are eng-ag-ed in the treatment of tuber- 

 culous patients, enable him to bring to bear a keen 

 critical faculty on the experience and experiments 

 of other investigators, with the result that the 

 work now before us may be looked upon as a 

 " classic," and one that for years to come will, 

 probably, remain the reference-book for those in- 

 terested in tuberculosis. 



The first three chapters, dealing with the inci- 

 dence, the mean annual mortality, and the decline 

 in mortality from tuberculosis, have already been 

 I dealt with by Dr. Cobbett in a series of lectures. 

 For the public health authority and the slum 

 reformer this section — forty-five pages only — will 

 be invaluable. 



After brief notes on the etiology of tuberculosis 

 and on the discovery of the tubercle bacillus, the 

 investigations of the Roval Commission on Tuber- 

 culosis, of Weber and his colleagues at the Kaiser- 

 Jiche Gesundheitsamt in Germany, of the Bureau 

 of Animal Industry in the United States, and of 

 French. Belgian, and Dutch workers is subjected 

 to critical examination and most impartial 

 summarisation. The evidence of infection and of 

 the importance of " massive " infection in the 

 production of disease, the mass varying with 

 different species of animals and the type — human, 

 i i.e. naturalised in the human subject; bovine, 

 ' naturalised in the bovine animal ; and avian, the 

 form of bacillus naturalised in, and specially infec- 

 NO. 2512, VOL. 100] 



tive for, birds— are in turn dealt with, first in 



relation to tuberculosis as it occurs in various 



animals, and then in relation to the production 



and spread of the disease from these animals to 



j man. After a discussion of the portals of 



entrance of the infective material, one of the 



i most closely reasoned sections of the book, 



I interesting observations as to the infectivity of 



I the different types of tubercle bacilli on the 



I various animals, (a) naturally, (b) as the result 



I of experiment, are recorded. From these it is 



j evident that many animals which, owing to their 



conditions of life, appear to be exempt from 



spontaneous " tuberculosis are comparatively 



easily infected " experimentally." Spontaneous 



tuberculous infection of the guinea-pig is so rare 



as to be almost non-existent, but to infection by 



bacilli of both human and bovine type it is 



extremely susceptible; whilst the cat, which 



appears to be specially susceptible to infection by 



the " bovine " tubercle bacillus, appears to be 



far more refractory to the " human type " of 



bacillus. 



As the result of the combined experience of the 

 workers dealt with in this book, it is laid down 

 that the tubercle bacillus of bovine type is present 

 in, and the cause of, the lesions of the ox, pig, 

 goat, sheep, horse, camel, cat, dog, monkey, and 

 man, in whom, in addition to the ordinary type of 

 bovine bacillus, a modified form is found in cases 

 of lupus. The avian type of bacillus, found especi- 

 ally in domesticated birds, has also been demon- 

 strated in the rabbit and pig, and in rats and 

 mice coming in contact with these birds. That 

 it plays little, and certainly no important, part in 

 the production of human tuberculosis is generallv 

 accepted. The " human type " of tul^ercle bacil- 

 lus, in addition to occurring in man, where it is 

 found in the lung and in a modified form in cases 

 of lupus, occurs in the dog, giving rise to about 

 half the cases of tuberculosis in that animal, and 

 in the localised glandular tuberculosis of the pig. 

 It has also/ been found in captive monkeys, in 

 caged parrots, and in certain mammals- — ante- 

 lope, elephant, and lion — kept in captivity. 



Dr. Cobbett, in his earlier chapters, maintains 

 that the human type of tubercle bacillus is respon- 

 sible for 94 per cent, of the fatal, mainly pulmo- 

 nary, cases of tuberculosis in man, the remaining 

 6 per cent, being caused bv the bovine bacillus. 

 (In an appendix, as the result of the consideration 

 of more recent investigation on tuberculosis of 

 bones and glands, there is evidence of modifi- 

 cation of this opinion.) Of the non-fatal cases of 

 tuberculosis, however, the bovine bacillus is 

 responsible for a much larger proportion — about 

 50 per cent. Infection with the bovine bacillus is 

 commonest in infancy, uncommon after five years 

 of age, and rare in adult life. It is associated 

 ! specially with tuberculosis of the alimentary 

 I tract and the associated glands, but bovine 

 I bacilli have undoubtedly been isolated from a 

 number of cases of pulmonary tuberculosis. In 

 Scotland, and especially in Edinburgh, the 

 bovine bacillus appears to play a more important 



