June ;, 1917] 



NATURE 



297 



cholera, but few have any regarding- the far more 

 deadly and insidious kala-azar, which, on account 

 of its extremely high mortality and the painfully 

 lingering nature of the disease, is without doubt the 

 most terrible scourge occurring in India. It is now 

 more than twenty years since I was fortunate enough, 

 when with less than three years' service, to be selected 

 to carry out the second investigation of the Assam epi- 

 demic of kala-azar, and it has never ceased from that 

 time to occupy my thoughts, although my opportuni- 

 ties for continuing my researches on it have sometimes 

 been more limited than I should have liked. For- 

 tunately, I have been able to discover how to prevent 

 the spread of the disease, and also independently to 

 find a cure for it. The time, therefore, seems to be 

 ripe for giving a brief popular summary of the pro- 

 gress which has been made in our knowledge of kala- 

 azar through the researches of the last twenty years, 

 which has resulted in a very great degree of success 

 as regards both the prevention and the cure of the 

 disease, although some links in the chain of infection 

 still remain to he forged. 



In the first place, I wish to remove a misconception 

 which I find is commonly prevalent among the public, 

 namely, that kala-azar and black-water fever are the 

 same disease, or at least intimately related. It is true 

 that some years ago a high medical authority did 

 make such a suggestion on theoretical grounds,, but I 

 do not think any medical man now holds that view. 

 As a matter of fact, it would be difficult to imagine 

 two more widely different conditions than the lingering 

 kala-azar and the shor^, sharp, black-water fever com- 

 plication of malariaj which ends in death or recovery 

 within a very few days. That black-water fever is 

 but a complication of malaria is a view with which 

 I am in agreement. But the differentiation of kala- 

 azar from chronic malaria was not possible before the 

 discovery of a distinct parasite in the former in 1903, 

 and up to quite recently it remained very difficult on 

 purely clinical grounds in many cases. It is, therefore, 

 not surprising that the two were for long confused even 

 by research workers, including myself in my report 

 of 1897 on the Assam epidemic, and a little later by 

 such a great authority on malaria as Sir Ronald Ross, 

 who proved malaria to be mosquito-borne. 



It is generallv known that kala-azar spread 

 through Assam for a number of years, causing a 

 great mortality; but it is difficult to convey to those 

 who have not seen its effects anything like an adequate 

 idea of the terrible nature of the affliction. At the 

 time of my investigation in 1896-97 the disease 

 was at its height in the Nowgong district, the 

 population of which in the decade 1891-1901 

 actually showed a decrease of 31-5 per cent., 

 against an increase of 9 to 16 per cent, in 

 the more easterly unaffected districts. Large areas 

 of land fell out of cultivation, and even at the 

 headquarters town of Nowgong land absolutely lost 

 its value, being quite unsaleable. When the tea- 

 gardens became infected in this district, and accurate 

 figures were available, it was found that the mortality 

 in several hundred carefully treated cases varied from 

 90 to q6 per cent. 



But I must pass on to show you some photographs 

 of cases taken during my investigation. The first 

 group was- taken in the Nowgong dispensary, and the 

 second in that at Mangaldai. Both show the great 

 emaciation contrasting with the tumid abdomens due 

 to great enlargement of the spleen, and often also of 

 the liver, while the skin becomes darker and more 

 muddv,' which, according to some, 'gave rise to the 

 term kala-azar or black fever. Now it will no doubt 

 occur to manv of you that "you have seen precisely 

 similar cases in malarious areas round Calcutta, and 

 you will ask, How do you differentiate between kala- 

 NO. 2484, VOL. 99] 



azar and chronic malaria? That, indeed, was the 

 problem which confronted me in Assam, with the 

 added difficulty that the disease was spreading and 

 causing an awful mortality such as malaria was not 

 known to do in Lower Bengal, and that the people 

 themselves had no doubt that the disease was an 

 infectious one, though malaria was not believed to be so 

 at the time of my investigation, which, of course, was 

 several years before the mosquito-borne theory of 

 malaria was established. In fact, there were at that 

 time two rival theories regarding kala-azar : one that 

 the disease was malarial, and therefore could not be 

 infectious ; and the other that it was infectious, and 

 therefore could not be malarial, so must be some 

 undescribed disease. I early set to work to find out 

 if kala-azar was infectious. I found that the disease 

 always began in a village through an infected person 

 coming to reside there, the next to be attacked being 

 those living in the same house as the infected 

 visitor. This naturally led me to suspect that the 

 disease was not malarial, yet I frequently found 

 malarial parasites in the blood (it was not tlien 

 known that in malarious parts many apparently healthy 

 persons harboured malarial organisms in their blood), 

 and, search as I would, I could find no differentiating 

 point from malaria. I therefore visited Sylhet, to the 

 south of the Khasia Hills, where kala-azar was then 

 unknown, and there found cases of malarial cachexia 

 which in every respect, including investigations of the 

 blood changes, resembled kala-azar of the Brahma- 

 putra Valley, except that they were much more chronic 

 and sometimes lasted as many years as epidemic kala- 

 azar did months-. With the boldness of com- 

 parative youth I therefore declared the spreading 

 kala-azar of Assam to be an epidemic infectious form 

 of malaria, corresponding in some respects with the 

 well-known Mauritius malarial epidemic of 1S77. We 

 shall see presently that I was partly wrong and partly 

 right in coming to this conclusion. 



However, I was not content with merely theoretical 

 considerations, but strove for practical results from my 

 inquiries. I therefore sought for more accurate 

 data on the tea-gardens, which had become 

 badly infected in the Nowgong district, and on 

 which I investigated many cases with the help of 

 my friend. Dr. Dodds Price, who has a unique experi- 

 ence of kala-azar and has rendered me the greatest 

 possible assistance throughout a number of years. I 

 ascertained that on one of his gardens so manv deaths 

 had occurred from kala-azar that two hundred new 

 coolies had to be imported at one time. He had 

 already independently recognised the infectiousness of 

 the disease before I went to Assam, and had arranged 

 for separate ooolie lines to be built to prevent as many 

 as possible of the new coolies going into the infected 

 houses of the old lines. Only one hundred and fifty 

 could be accommodated in the new lines, so fifty had 

 to go into the old ones. On learning this, I at once 

 set to work to ascertain the results of this important 

 measure, and we found that in the course of two years 

 no single case of kala-azar had occurred in the new 

 lines (and the same was true eighteen years later), 

 while no fewer than 16 per cent, of the new coolies 

 living in the old infected lines were already dead of the 

 disease, although the two sites were only about two 

 hundred yards apart. This experience led me to urge 

 moving out all the healthy people from the infected 

 lines into new ones, taking none from infected houses, 

 segregating the remaining infected families, and 

 destroying the old houses. The results were so suc- 

 cessful that the plan was repeated by Dr. Price 

 on other gardens, and 'r 1913, during a visit to Assam 

 in the Puja vacation, we worked out the results of 

 eighteen years' experience. This may briefly be sum- 

 marised by saj'ing that the dread disease had been 



