MICROBIAL DISEASES OF MAN AND ANIMALS. 675 



the body of the host, by binary division. If spleen pulp, or blood, containing such 

 organisms be placed on a suitable culture medium, they will develop, in three or four 

 days, into herpetomonad forms. The large nucleus becomes the nucleus of the fla- 

 gellate form, while the smaller, rod-like, mass becomes the kinetonucleus, from which 

 arises the flagellum. The method by which the infection is acquired is unknown; 

 it is probably by the bite of an insect, perhaps a bed bug. 



Kala azar is a chronic disease characterized by emaciation, by an 

 irregular fever and by considerable enlargement of the spleen. There 

 is great loss in strength and energy. 



Although there may be periods of apparent amelioration, the disease 

 usually progresses steadily, in spite of treatment, to a fatal termination. 



DELHI BOIL. 

 Herpetomonas furunculosa. 



This disease occurs in much the same places as does kala azar; it has, 

 however, been seen in Brazil, where kala azar is unknown. 



Delhi boil is caused by Herpetomonas furunculosa. The parasites are found at the 

 spreading edge of the ulcer. As they occur in the ulcer they are oval parasites, almost 

 identical with those which are found in the spleen of persons suffering from kala azar. 

 If infected material be placed on a culture medium, flagellated forms will be developed. 



Delhi boil is a painless ulcer, covered by a dry scab, which usually 

 occurs about the face, or other uncovered portions of the body. If the 

 sore be left untreated, it cures itself after some months. In countries 

 where it occurs, Delhi boil is particularly liable to from at the site of a cut 

 or abrasion. It is possible that, in some cases, the infection may be carried 

 to a wound by house flies. 



The condition is best treated by free excision. In places where it is 

 endemic, care should be taken to avoid the possibility of infection by care- 

 fully protecting all wounds, no matter how small. 



TRYPANOSOMA 



Trypanosomes are parasitic in insects, fish, reptiles, birds, and mammals in 

 all parts of the world. Many of them seem to be harmless parasites; others 

 cause very serious diseases. 



Sleeping sickness is the most important of the diseases due to trypanosomes. 

 It is caused by Trypanosoma gambiense. 



