LEISHMANIA DONOVANI 417 



effected, and as it showed no signs of becoming attenuated, it is possible that this 

 animal may prove useful for experimental purposes, and lead to important results 

 on the aetiology and transmission of kala azar. Meleney (1925) has shown that the 

 infection progresses steadily in its intensity till, at the end of fifteen months, the 

 tissues of the spleen, liver, bone marrow, lymphatic glands, and intestinal mucosa 

 have been largely replaced by macrophages packed with parasites. The parasites 

 are found also in other organs, including the meninges, where the macrophages occur. 

 They were also demonstrated in th-) glandular cells of the liver. 



Franchini (1922m) claims to have produced infection of the plant Eupliorhia 

 ipecacuanha by inocidating it with cultures of L. donovani. 



TRANSMISSION. — Since Eogers's demonstration of the development of 

 flagellates of the leptomonas type from leishmania, and the recognition 

 of the close resemblance of these to natural insect flagellates, it has been 

 generally assumed that Leishmania donovani has an invertebrate host. 

 Though many attempts have been made to discover such a host and the 

 method of transmission of kala azar, the problem still remains unsolved. 

 Many different invertebrates, chiefly bugs and fleas, have been considered, 

 and some observers claim to have effected transmission of infection by the 

 agency of fleas. As leishmania are present in the peripheral blood of cases 

 of kala azar, they are readily ingested by blood-sucking insects, while 

 the flagellate forms which appear in cultures undoubtedly represent an 

 insect developmental phase, as they do in cultures of trypanosomes, the 

 invertebrate hosts of which are known in many cases. It was suggested 

 by the writer (1914o) that oriental sore and kala azar may be caused 

 by insect flagellates which only accidentally infect man. Normally, the 

 flagellates would pass from insect to insect, as do all naturally occurring 

 insect flagellates. Occasionally, they would infect human beings, and 

 give rise to the diseases mentioned. According to this view, the virus 

 could be maintained indefinitely in the insects, which would be infected 

 from one another, though an insect would be capable of infecting itself 

 by sucking the blood of an infected human being. 



As first demonstrated by Patton (1912a), it is well known that L. 

 donovani will develop into the leptomonas form in the stomach of the bed 

 bug. The flagellates can be recovered from the intestine of the bug by 

 the culture method as long as six weeks after parasites were first ingested. 

 Mice can be infected with the forms in the intestine of the bug nine days 

 after the feed on kala azar cases. An enormous amount of time and 

 energy has been spent in investigating the claims of the bed bug, but 

 no actual proof that it is the transmitter of kala azar has been obtained. 

 Kecently, Knowles, Napier, and Smith (1924), Christophers, Shortt and 

 Barraud (1925, 1925a), and Shortt, Barraud and Craighead (1926) have 

 found that female Phlebotomus argentipes acquire a heavy leptomonas 

 infection of the intestine and pharynx after feeding on kala azar cases. 



I. ' 27 



