418 FAMILY: TRYPANOSOMID^ 



The flagellates may even extend into the buccal cavity. This fact, com- 

 bined with Sinton's observation that the distribution of the disease in 

 India corresponds with that of P. argenti])es, leaves only a definite trans- 

 mission experiment to prove that kala azar is conveyed by the bite of the 

 sand fly. The claim that the flea is the transmitter of kala azar in the 

 Mediterranean area has not been substantiated. If it be assumed that 

 an insect vector exists, then there are two possibilities as to the mode of 

 infection. The organism may either be injected by the insect by way 

 of the proboscis (inoculative), or it may be voided in the faces of the insect 

 in some form, and thus infect the wound or be ingested (contaminative). 



It has been suggested that L. donovani may escape in the faeces of 

 patients. Manson and Low (1904) demonstrated its presence in the ulcers 

 of the intestine, while Perry (1922) has seen the villi heavily infected with 

 parasites. Mackie (1914c) saw bodies resembling leishmania in mucus 

 from the intestine, but Knowles (1920) examined mucus very carefully, 

 and though he saw bodies more closely resembling leishmania than those 

 noted by Mackie, he pronounced no opinion as to their nature. It seems 

 probable that these bodies are yeasts, which frequently show a striking 

 resemblance to leishmania in stained films. Shortt (1923) has cultivated 

 leishmania from the urine of kala azar cases, so that the possibility of 

 spread of infection by water has to be considered, but experience has 

 shown that the parasites quickly degenerate in water. The nature of the 

 parasite is not in favour of such a method of transmission, though Adel- 

 heim (1924) has noted that a healthy mouse kept in a jar for five months 

 with an infected mouse contracted the disease. As the infected mice 

 commonly had ulcers in the intestine in which parasites could be demon- 

 strated, it was thought that oral contamination was responsible for this 

 contact infection. 



The common association of ankylostomiasis with kala azar has 

 suggested the possibility of the ankylostomes being a source of infection. 

 Knowles (1920) investigated the worms taken from kala azar cases, and 

 even the eggs and embryos hatching from them, without finding anything 

 to support this view. 



The following experimental work with insects has been carried out 

 with a view to the discovery of a transmitting host: 



Bugs. — The bed bug {Cimex roiundaius) was suspected by Kogers as a possible 

 carrier of kala azar on account of its frequent presence in houses where cases of 

 the disease occurred. Patton (1912a), working in Madras, also favoured this view, 

 and conducted a series of experiments by which he claimed to have proved the 

 correctness of the theory. By feeding bugs on cases of kala azar, in which the 

 leishmania were numerous in the perijiheral blood, and dissecting them at varying 

 intervals, he found that the leishmania had developed into flagellates of the lepto- 

 monas form as they do in cultures, and that some multiplication had taken place. 



