IS^ 



NATURE 



[August ii, 192 i 



as to the importance of tuberculosis " carriers " — 

 i.e. centres of infection, themselves healthy to all 

 intents and purposes. He claims (though the 

 claim is not universally admitted) that von 

 Pirquet's method of diagnosis is sufficiently char- 

 acteristic to allow of a decision as to whether a 

 patient is the subject of bacillary infection, or, in 

 other words, capable of reacting to tuberculin 

 as a result of the presence in the patient of a 

 sensitising substance derived from the tubercle 

 bacillus. Prof. Calmette holds, moreover, that 

 by means of this reaction it is possible to work 

 on a grand scale and to determine whether peoples 

 and tribes, infants and adults, are infected by, 

 or free from, tuberculosis. He quotes Col. 

 Cummins and others to the effect that among 

 African tribes about the equator where civilisa- 

 tion has not yet penetrated, and among the 

 nomadic tribes of Arabs and Berbers, tuberculous 

 infection is non-existent, or very rare, whilst 

 in Natal, among the Zulus in the Transvaal, and 

 in Madagascar, as also in the larger cities of 

 North Africa, it is very prevalent. Those living 

 in huts and native villages are, however, gradu- 

 ally becoming infected by contact with men from 

 without. In the hinterland of the Cameroons 

 from 3 to 6 per cent, only of adults are yet 

 affected, whilst many aboriginal tribes are still 

 quite free. 



In civilised countries, although the reported per- 

 centage of tuberculous infection is comparatively 

 high, a careful examination by the von Pirquet test 

 and an examination of patients who die from other 

 diseases would, Prof. Calmette claims, indicate 

 the infection by the tubercle bacillus of many 

 who, as yet, show no signs of tuberculous disease, 

 and he believes that in the overcrowded 

 cities of Europe and the United States few escape 

 tuberculous infection, although the chances of 

 death from tuberculosis are little more than one 

 in eight. In the country districts the figures are 

 not so high. Amongst the Kalmucks, even 

 where the inhabitants have little intercourse 

 with towns, 694 per cent, of the men and 306 

 per cent, of the women give a positive tuber- 

 culin reaction, whilst on the outskirts of the same 

 territory, where commercial relations with the 

 Russian population are very close, 95-7 per cent, 

 of male adults and 88-5 per cent, of women give 

 a positive reaction. Moreover, where differences 

 occur, these are due very largely to the fact that 

 tuberculous infection has been implanted in certain 

 races over a longer or shorter period of time, 

 although infections are also variable, being rare 

 and slight or frequent and massive according to 

 the particular mode of life of the people. 

 Those who have been longest protected bv 

 virtue of their isolation from contact with 

 the tuberculous prove to be most susceptible, 

 aboriginal tribes and infants being the virgin 

 soil on which the tubercle bacillus flourishes 

 most luxuriantly. In 4he races that have 

 been contaminated for centuries and exposed from 

 infancy the disease assumes a chronic, slowly 

 progressing form ; but almost all become in- 

 NO. 2702, VOL. 107] 



fected. He hnds evidence in support of his con- 

 tention in the susceptibility of the bovine species 

 to tuberculosis in the domesticated condition, 

 although the wild cattle of Madagascar and of the 

 pampas of the Argentine are said to be free from 

 this disease. (It was found by the Royal Commis- 

 sion on Tuberculosis that Jersey cattle, though free 

 from tuberculosis in the island, were readily in- 

 fected when brought over to this country.) 



Prof. Calmette is of opinion that the spread of 

 human tuberculous infection throughout the world 

 is due entirely to disseminators of virulent bacilli, 

 most frequently through persons suffering from 

 phthisis, who scatter enormous numbers of bacilli 

 in their sputum and intestinal excretions either 

 directly or by means of objects soiled by them, or 

 again through the agency of living carriers, such 

 as flies. These open tuberculous cases are not the 

 only factors in the dissemination of the disease. 

 Many apparently healthy individuals suffering 

 from latent or concealed tuberculous lesions which 

 can be detected only by the tuberculin reaction 

 are a source of danger in that they eliminate 

 bacilli intermittently in their glandular or intes- 

 tinal excretions, thus spreading infection in their 

 environment. 



E. C. Schroeder and W. E. Cotton found that 

 46 per cent, of cows giving a positive tuberculin 

 reaction and showing no clinically demonstrable 

 lesion discharged bacilli intermittently in their 

 excreta, and that swine fed on these excreta easily 

 became infected. 



Similar observations were made by the Royal 

 Commission on Tuberculosis, which, injecting 

 tubercle bacilli into the circulating blood of 

 healthy cattle, demonstrated their early appear- 

 ance in the milk, whilst Calmette and Guerin 

 showed that some of the bacilli injected into the 

 blood-stream are eliminated through the bile pas- 

 sages. Lydia Rabinowitsch and Kempner, Tirze, 

 with others in Germany, and Sheridan Delepine 

 in England, have made similar observations with 

 regard to the mammary glands of cattle. More 

 recently it has been claimed by several observers 

 that bacilli may often be found in the milk of 

 tuberculous human mothers, even when the 

 disease is in its early stages, or where only 

 lymphatic glandular lesions are present. Prof. 

 Calmette suggests that in the children of these 

 mothers serious forms of tuberculosis are set up 

 by slight but oft-repeated infections through 

 breast-feeding or through prolonged or numerous 

 accidental contacts with intermittent disseminators 

 of bacilli. He goes further, and holds that when 

 tuberculosis appears in environments where it has 

 hitherto been absent it may have been introduced 

 by a bacillus-carrier unrecognised because appar- 

 ently healthy, which nevertheless has spread viru- 

 lent germs either in excretions or through gland- 

 ular secretions — e.g. milk in the case of lactating 

 women ; also that the disease in these more re- 

 cently contaminated countries is more serious and 

 more rapidly progressive than in the countries 

 longer infected, and that it then assumes the form 

 met with in young children rather than that met 



