398 SANITARY ENTOMOLOGY 



thrives only at temperatures from 16° to 26° C. (61° to 79° F.) and 

 is therefore unfitted to exist in the human body. This is further evidence 

 that the flagellate is a tvpical insect form. They have failed to find a 

 postflagellate cystic form in the stomach of the bug. 



Transmission b}' insects has not been demonstrated, although there is 

 considerable evidence that it can not be transmitted by the bite of the 

 bedbug in which the organism normally flagellates. Cornwall and ^Nlenon 

 claim that there are only two possible means of transmission left ; rupture 

 of a bug containing flagellates in the neighborhood of a puncture or 

 abrasion, and passage of cystic forms into the feces, and there is no 

 direct evidence for either. The}^ lean to the rupture theory because it 

 seems to account for the peculiar distribution of kala azar. It is com- 

 paratively rare and often localized in certain dwellings. The bug does 

 not live on the person, but in buildings and furniture. It does not gener- 

 ally crawl over the skin when feeding but attacks exposed parts from a 

 fairly safe position. It must therefore be a comparatively rare event for 

 a bug to be ruptured on the skin of its occasional host. They may be 

 transported from place to place in furniture and clothing, and may go 

 from house to house in search of food. The bug is also more or less 

 localized. As the bug would be sacrificed in the act of transmission, it is 

 clear that a human reservoir of the disease must be at hand if the bugs in 

 a building are to remain dangerous. Knowles suggests the possibility 

 of hereditary transmission in the bedbug or in intestinal worms. 



Leishmania tropica (Wright), the cause of ORIENTAL SORE, is 

 also thought to be transmitted by insects. Wenyon found that the bed- 

 bug Cimex lectularius could take up the parasites and that develop- 

 mental stages were demonstrable in its gut. Patton (1912) obtained 

 development of the parasite into flagellate forms in Cimex Jiemipterus at 

 low temperature (22° to 25° C.) and produces considerable evidence 

 in favor of these species as the natural carrier. 



Mastigophora: Spirochaetacea : Spirochaetidae 



S piroschaudinnia herhera (Sergent and Foley), the cause of NORTH 

 AFRICAN RELAPSING FEVER, is spread by the body louse. Sergent 

 and Foley have obtained negative results with Cimex lectularius. 



S piroschaudinnia duttoni (Now and Knapp), the cause of TROP- 

 ICAL AFRICAN RELAPSING FEVER, is normally spread by ticks. 

 Breinl, Kinghorn and Todd in 1906 and Nuttall in 1907, were unsuc- 

 cessful with transmission experiments with Cimex lectularius. 



S piroschaudinnia recnrrentis (Lebert), the cause of EUROPEAN 

 RELAPSING FEVER, is normally transmitted probably by the body 



