KALA-AZAR 167 



attended the investigations undertaken for its elucida- 

 tion, and because of the remarkable series of observations 

 which have resulted in the discovery of the cause of the 

 disease and the nature of the specific parasite, and 

 probably of its mode of transmission and prophylaxis. 



The great mortality caused by epidemics of kala-azar 

 in Assam, during the last two decades of the nineteenth 

 century, prompted the Government of India to send 

 one medical officer after another to investigate the 

 disease, and if possible to discover its cause and devise 

 methods for its prevention. All the investigations so 

 undertaken, although carried out with great care, failed 

 in their object. One observer, influenced 'by the anaemia 

 of the patients and by the discovery that many of them 

 harboured ankylostomes, considered that the disease 

 was essentially ankylostomiasis. Another came to the 

 conclusion that kala-azar was malarial fever, in an 

 intense and communicable form ; and a third investigator, 

 while noticing the absence of malarial parasites in the 

 blood and of melanin pigment, thought that it was a form 

 of malaria with marked incidence on the liver and spleen, 

 and with a mortality enhanced by the concurrence of 

 ankylostomiasis or of dysentery ; another believed it to be 

 undulant fever (Malta fever). The subject stood thus when, 

 in May, 1903, Leishman published in the British Medical 

 Journal a short note entitled " On the Possibility of the 

 Occurrence of Trypanosomiasis in India." A few years 

 previously, in 1900, he had noticed in smears made from 

 the spleen of a soldier, who had died at Netley of tropical 

 cachexia and dysentery, contracted near Calcutta, enor- 

 mous numbers of the small, round, oval bodies, with the 

 two characteristic chromatin masses already described. 

 As to the meaning of these bodies Leishman was at a loss. 

 In 1903, however, he found almost exactly similar bodies 

 in the spleen of a white rat, which forty-eight hours 

 previously had died of infection with the trypanosome of 

 nagana. Up to the time of its death the blood of this 

 rat was swarming with trypanosomes, and experiments 



