358 SANITARY ENTOMOLOGY 



of the flea and are voided in its feces and obtain entrance to the host by 

 the scratching in of feces of infected fleas, or by the licking up of the 

 feces or the flea. 



The five trypanosomes are all taken up from the blood and pass 

 through a definite life cycle in the flea, passing out of its feces, and 

 obtain entrance to the host by being licked up in the feces. This may 

 also happen in the case of leptomonads. 



The crithidias and leptomonads belong primarily to the fleas alone, 

 and pass through their cycle of existence in the flea body and out of its 

 feces and are taken up by feeding on the infected feces, probably by 

 the larva. 



The tapeworms are taken up as eggs by the larvae feeding in filthy 

 dirt. They develop in the flea and are taken into the vertebrate host 

 when it licks up the flea from its body. 



The filaria is taken from the blood of the host as an embryo, and 

 develops in the flea, but we do not know how it gets back to the 

 host. 



In addition to all these diseases caused by organisms, fleas may cause 

 a dermatitis. This is especially true of the chigoe, Dermatophilus pene- 

 trans, which becomes fixed to its host and sometimes even causes AIN- 

 HUM, or the loss of a member, such as a toe. It will be discussed in the 

 next lecture on fleas. 



REFERENCES 



Bacot, A. W., and Martin, C. J., 1914. — Joum. of Hygiene, Plague Sup- 

 plement III, Jan. 14, 1914, pp. 423-439. 

 Brumpt, E., 1913.— Bull. Soc. Path. Exot., vol. 6, pp. 169-170. 

 Fantham, H. B., Stephens, J. W. W., and Theobald, F. V., 1916.— The 



Animal Parasites of Man. 

 Herms, W. B., 1915. — Medical and Veterinary Entomology. Macmillan 



Co., 393 pp. 

 Johnston, J. H., 1913. — Proc. Roy. Soc. Queensland, vol. 24, pp. 63- 



91. 

 Joyeux, Charles, 1916. — Bull. Soc. Path. Exot., vol. 9, No. 8, pp. 578- 



579. 

 Laveran, A., and Franchini, G., 1913. — C. R. Acad. Sci., Paris, vol. 47, 



No. 18, pp. 744-747. 

 Laveran, A., and Franchini, G., 1914. — Bull. Soc. Path. Exot., vol. 7, 



pp. 605-612. 

 Liston, -W. G., 1905. — Journ. Bombay Nat. Hist. Soc, vol. 16, pp. 



253-273. 

 McCoy, G. W., and Chapin, C. W., 1912. — Joum. Infect. Diseases, vol, 



10, No. 1, pp. 61-72. 



