174 



Cornwall (J. W.). A Contribution to the Study of Kala-Azar. (ii).— 

 Ind. Jl Med. Research, Cahutta, iv, no. 1, July 1916, pp. 105-119, 

 1 plate. [Received 12tli September 1916.] 



Further experiments were made in order to determine whether 

 Cimex hemiptems {rotundatus) is able to transmit Leishmania donovani, 

 the parasite of kala-azar (1) by biting, (2) through the medium of its 

 faeces, or (3) by being devoured by another insect or vertebrate. In 

 the first case, infected bugs were unable to inoculate a sterile culture 

 fluid either with flagellates or "with bodies capable of developing into 

 flagellates. In the second case, if a viable cystic form of the parasite 

 were present in the faeces, infection would be transmitted if the faeces 

 came into contact with feeding punctures, wounds, etc., on the skin of 

 the host. As yet no such forms have been found in the rectum or faeces 

 of the bug, and it is therefore improbable that infection can be carried 

 by this means. A number of flagellate and non-flagellate forms were 

 found in the rectum, but these all showed signs of degeneration and are 

 beheved by the author to have reached this position accidentally from 

 the stomach. With regard to the third case, ants are known to eat 

 bugs and it is thus possible that food can be contaminated by these 

 insects. The common species of cockroaches in the region of the 

 Nilgiri Hills do not attack bed-bugs or their eggs. Further observations 

 are needed on the capacity of vertebrate enemies of bed-bugs to carry 

 infection. 



Investigations were carried out on the formation of the thick-tailed 

 stage in the life-history of L. donovani and L. tropica. Thi.s form only 

 arises in the stomach and intestine of C. hemipterus and is produced 

 more abundantly in the presence of human blood. Similar forms were 

 not produced experimentally in Xe^iopsylla, Margaropus and Triatoma 

 {Ccy)iorhinus) rubrofasciata. It is suggested that similar investigations 

 should be conducted on Simulium, Phlebototnus, etc. If the short- 

 tailed stage is a developmental or resistant form, then its presence 

 in the bug would indicate that the latter is concerned in spreading 

 both kala-azar and oriental sore. If, on the other hand, this stage 

 appears in the stomachs of other insects as well as that of the bug, 

 it may be regarded as due to an unfavourable environment, and in 

 consequence, the bug would not be responsible for the spread of 

 disease. A flagellate infection which had died out from the stomach 

 of the bug was not renewed after a second feed on sterile blood. 

 Cystic forms capable of becoming flagellates do not therefore remain 

 in the stomach. No intracellular stages of L. donovani were found to 

 occur in the stomach. 

 V Triatoma rubrofasciata was fed on citrated human blood and 



flagellate culture. Very few living flagellates were found in the stomach 

 at the end of two days and none at the end of four days. T. rubro- 

 fasciata is therefore not an intermediate host of L. donovani. The 

 fresh serums of man, goat, sheep and guinea-pig were fatal to living 

 flagellates of L. dmovani, but except in the case of the goat, the 

 unfavourable action was destroyed by heating to 131° F. for half an 

 hour. Few ill effects were observed from the serum of rabbit, hen, dog 

 and cat. 



When bugs were allowed to feed on the ulcer of oriental sore, from 

 which cultures of L. tropica had previously been made, subsequent 



