268 ENTOMOLOGY 



Nicolle and his colleagues demonstrated in 1913 that the European 

 and North African form of the disease is transmitted by the body 

 louse, and the head louse as well, though not by their bites. When 

 the lice are crushed and the infected contents of- their bodies rubbed into 

 wounds made by the lice, or into abrasions of the skin, or are transferred 

 as by the fingers to a mucous membrane, such as the conjunctiva of 

 the eye, the disease is produced. 



It was proved that, in some instances at least, infection could be 

 transmitted through the eggs to the lice of the next generation. The 

 European form of the disease may be conveyed by the bedbug also, 

 according to some investigators. In central Africa a common tick 

 is the agent of transmission, and in Mexico and Central America ticks 

 and bedbugs are suspected. 



TRENCH FEVER 



One of the most disabling diseases in the Great War was trench 

 fever. The experiments made by British and American investigators 

 in 1918 proved that this disease also is transmitted by the body louse, 

 Pediculus corporis. The physical causeof the fever is conveyed in the 

 feces of the lice and inoculation occurs through scratching by the victim, 

 and possibly also by means of punctures made by the lice. The specific 

 cause of trench fever is, however, not actually known as yet. 



OTHER DISEASES 



Cholera is undoubtedly transmitted by flies. As long ago as 1899 

 Dr. Nuttall wrote: "The body of evidence as to the role of flies in the 

 diffusion of cholera is, I believe, absolutely convincing." 



Dysentery is probably carried by flies, as Dr. Orton and others have 

 inferred from their experiments. 



Spillman and Haushalter, as well as several others, examined flies 

 that had fed on tubercular sputum and found in the intestinal contents 

 and in the dejections of these flies the bacilli of tuberculosis. 



Dr. F. T. Lord summarizes his important investigations on this 

 subject as follows: 



" i. Flies may ingest tubercular sputum and excrete tubercle bacilli, 

 the virulence of which may last for at least fifteen days. 



"2. The danger of human infection from the tubercular fly-specks 

 is by the ingestion of the specks on food. Spontaneous liberation of 



