578 The Blood Flagellates 



tion and may explain the sporadic occurrence of kala-azar year after year 

 in households and other small groups (48). 



In summary, the essential pathological characteristic of kala-azar in 

 man, monkeys and hamsters (40) is the increase in lymphoid-macrophage 

 cells. The macrophages ingest L. donovani but are imable to prevent their 

 multiplication after ingestion. Consequently, it is uncertain "whether the 

 reticulo-endothelium is valuable, as the only defense the body has, im- 

 perfect as it is, or deleterious, as being the most suitable location for the 

 parasites" (70). 



Oriental sore 



Distribution. Classical oriental sore, as seen in Eurasia and Africa, 

 is a widespread type of leishmaniasis. In Europe, the disease has been 

 known in Spain, Italy, Greece, and rather rarely in France. In Africa, 

 oriental sore has been fairly common in Egypt, the Sudan, Algeria, French 

 Congo, and Nigeria. In Asia, the disease seems to be endemic in Arabia, 

 Asia Minor, Mesopotamia, Persia, subtropical parts of the U.S.S.R., and 

 parts of India. 



The causative organism. L. tropica was recognized as the causative 

 organism when Wright described the parasites in 1903. Morphologically, 

 this flagellate (Fig. 12. 1, F) is essentially identical with L. do?wvani. 

 Like the latter, it is usually found inside macrophages in man. 



The invertebrate phase of the cycle, as traced in Phlebotomus papatasii, 

 is initiated by metamorphosis of the ingested leishmanial forms into 

 leptomonads in the midgut. With continued multiplication, the infection 

 gradually extends into the pharynx and mouth cavity. In at least a few 

 sandflies, the flagellates eventually reach the anterior part of the epi- 

 pharynx. The last step apparently is essential for transfer to man. 



Symptoms and pathology. The incubation period ranges from a few 

 days to several months, and sometimes even three or four years. The skin 

 lesion begins as a small pimple, resembling the swelling which sometimes 

 follows insect bites. The pimple grows and may eventually develop into 

 a nodule an inch or more in diameter. Clinically, the non-ulcerating 

 nodule, the superficial flat ulcer, and the deeper boil may be distin- 

 guished. The non-ulcerating lesion, after a year or so, dries up to a scab 

 which drops off, leaving a scar. More commonly, the surface of the nodule 

 breaks down to form an ulcer. Secondary invasion by bacteria usually 

 occurs, and the ulcer may grow to a diameter of several inches. Sections 

 through a sore show an oedematous dermis with many macrophages, 

 pressure from which may cause local destruction of hair follicles and sweat 

 glands. Patients often show only one or two lesions, although sometimes 

 more (even a dozen or so). There is usually little constitutional disturb- 

 ance. However, lymph glands near sores may become swollen, and fever 

 sometimes occurs. 



