672 LEISHMANIOSIS 



the bed-bug is the extra-human host. This view was elaborated 

 by Patton, who brought forward facts to show that multiple cases 

 might occur in a house while neighbouring houses were free from 

 the disease. This observer also fed the common insect parasites 

 of man in Madras on patients whose peripheral blood contained 

 the Leishmania, and observed the flagellate stage in the bug, 

 cimex rotundatus, especially after a single feed with human blood. 

 This last fact he explains by supposing that human blood contains 

 substances inimical to the full development of the parasite. As 

 in all experiments of the kind, difficulties arise in consequence 

 of the great variety of flagellates which normally inhabit the 

 intestine of insects. The rarity of the Leishmania in the 

 peripheral blood has been advanced as an argument against 

 infection taking place by means of a blood-sucking insect, but 

 in certain cases considerable numbers occur in the blood, and, 

 apart from this, invisible spirillary forms may be instruments of 

 infection. It may be said here that all attempts to communicate 

 the disease to animals have been hitherto unsuccessful. 



With regard to kala-azar as a whole, we may say that we are 

 dealing with a distinct disease fairly widespread in various sub- 

 tropical regions. All attempts to include it among the malarial 

 cachexias, which clinically it so much resembles, have failed. 

 In this atypical cachexial fever there is always present a parasite 

 of very special characters belonging or closely allied to a group 

 which contains many varieties capable of giving rise to similar 

 diseases. Beyond this we cannot go, but there is strong pre- 

 sumptive evidence of the parasite described being the cause of 

 the disease. 



Methods of Examination. The Leishmania donovani can be 

 readily seen in films or sections of the organs in which we have 

 mentioned its occurrence. These should be stained by the 

 Romanowsky stains. Fluid taken from the enlarged spleen with 

 a perfectly dry needle during life may be examined, but it is 

 probable that in this disease puncture of the spleen may not be 

 a very safe operation, as death from hemorrhage from this 

 organ is a not uncommon natural terminal event. During life 

 the main points on which a pathological diagnosis may be based 

 are the demonstration of the parasite in the circulating blood, 

 which should always be attempted by means of thick films, the 

 absence of the malarial parasites from the blood, and the features 

 of the leucopenia which have been alluded to. 



Leishmania Infantum. Nicolle, working in Tunis, observed 

 a disease clinically identical with kala-azar, but presenting the 

 peculiarity of affecting children between two and five years of 



