BEDBUG AS DISEASE CARRIER 377 



interest in preventive medicine, is still very indefinitely known. 

 Various authors have associated bedbugs with a number of 

 human diseases but the evidence brought forth in support of 

 these insects being the normal transmitters of the diseases in 

 question rests on insecure foundations. Ordinarily bugs are 

 handicapped in the extent to which they are able to spread 

 disease by their non-migratory habits. Unlike many parasites 

 they are not usually carried about by human beings, but remain 

 permanently in places occupied by their hosts. It is obvious, 

 therefore, that bugs are limited in the spreading of disease to the 

 occupants of the infested place. Should this be a private home, 

 spread of disease by bugs would be practically limited to a single 

 family. In case of infested hotels, rooming houses, sleeping 

 cars, boats, etc., conditions are ideal for the spread of disease by 

 bugs, and it can hardly be doubted that it is in such places that 

 most of the damage is done. 



One of the first accusations against the bedbug as a disease 

 carrier was made by Patton, of the British Medical Service in 

 India, who in 1907 brought evidence against this insect as a 

 carrier of Indian kala-azar (see p. 79). Patton followed what 

 he believed to be developmental stages of the parasite of kala- 

 azar, a species of Leishmania, in the gut of the Indian bedbug, 

 Cimex hemipterus (rotundatus) . Subsequent investigations, es- 

 pecially recent ones by Cornwall, have shown that infection of 

 bedbugs by feeding on kala-azar patients is very rare, and that 

 the bugs cannot, apparently, transmit the infection either by 

 biting or by means of infected faeces. The rare infectivity of 

 bugs which have fed on kala-azar patients, however, may be 

 correlated with the fact that the kala-azar parasites are rare in 

 the peripheral blood. As pointed out by Price and Rogers, 

 even if only a small per cent of bugs become infective, where 

 they are as numerous as they are in the coolie huts in India, 

 they would be able to spread the disease successfully. Donovan 

 believes the kala-azar parasites may utilize the Malay bug, Tri- 

 atoma rvbrofasciatus (see p. 381), as an intermediate host, but 

 rec~ent work is tending to throw doubt on the necessary in- 

 strumentality of any insect in transmitting the disease. Bed- 

 bugs have also been associated with another Leishmania disease, 

 oriental sore, but it is doubtful whether the bugs act as more 

 than mechanical disseminators of the parasite, if at all. Yaki- 



