MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 88 1 



disease. Nevertheless, it is not certain that Leishmania infantum and 

 L. donovani are not identical. It is confined almost wholly to young 

 children in whom it usually runs a fatal course. This disease has 

 been transmitted to lower animals and the infection occurs naturally 

 in dogs, especially those of infested districts. Recent investigations 

 indicate that the dog furnishes a source of infection for human beings 

 and that transmission is affected through the agency of a species of flea. 



LOCALIZED LEISHMANIASIS (DELHI BOIL) 

 Leishmania tropica Wright, 1903 



The localized forms of leishmaniasis occur in widely distributed localities 

 throughout the tropics, and numerous local names have been applied, Aleppo Boil, 

 Oriental sore, Bagdad Boil, Biskra Button, etc. In South America likewise a 

 number of local names have been applied, Espundia, Uta, Bubas, Braziliana and 

 Forest Yaws. In certain forms of the disease the mucous membranes are invaded 

 with loss of tissue of the nose and palate causing great deformity. 



The parasites are found at the spreading edge of the lesions. 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 develop. In many cases the organisms are 

 difficult to find. 



Delhi boil is a painless ulcer, covered by a dry scab. It 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 form 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 may be treated by free excision although it runs a 

 self-limited course. In places where it is endemic, care should be 

 taken to avoid the possibility of infection by carefully protecting all 

 wounds, no matter how small. 



TRYPANOSOMA (Gruby, 1843) 



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, since it affects human beings, is regarded as the most im- 

 portant of the diseases due to trypanosomes. 



56 



