RELATIONS OF PROTOZOA TO MAN 



71 



Figure 35. Leishmania donovani, the parasitic flagellate of kala-azar in Asia. Form on left, 

 stage in man; forms in middle and to right, stages in the sandfly (Phlebotomus). Highly magnified. 



mitted by bloodsucking kissing bugs. Infec- 

 tion takes place by way of the bugs' feces, 

 which the patient probably rubs into the 

 puncture wound after the insect has ceased 

 feeding. Besides the flagellated form which 

 may be found in the blood stream, a spheri- 

 cal, nonflagellated stage is frequently en- 

 countered in the tissues. The muscular tissue 

 of the heart is particularly susceptible, and 

 death from cardiac failure is common. Kiss- 

 ing bugs feed on other animals besides man, 

 the armadillo being a particularly important 

 reservoir of infection. 



Leishmania infections are also of more 

 than one type. Kala-azar or dumdum fever, 

 a disease common in India, northern Africa, 

 and parts of South America, is caused by 

 Leishmania donovani (Fig. 35). It is trans- 

 mitted by the bites of small sandflies. Per- 

 sons suffering from kala-azar usually show 

 enlargement of both spleen and liver, gen- 



eral emaciation, and a peculiar darkening of 

 the skin. Various antimony compounds are 

 used in treatment. Oriental sore is caused by 

 Leishmania tropica. It occurs in northern 

 Africa, southern Asia, and southern Europe. 

 Espundia, caused by Leishmania brasilienis, 

 is limited to Central and South America. All 

 types of leishmaniasis are carried by sandflies. 



Parasites of the digestive tract 



The intestinal- and cavity-inhabiting 

 forms include representatives of all 4 classes 

 of Protozoa. Entamoeba (formerly Enda- 

 moeha) gingivalis lives in the human mouth. 

 It is sometimes found associated with pyor- 

 rhea, though it is not considered the primary 

 cause of that condition. Kissing is the com- 

 monest mode of transmission. Over 50 per 

 cent of the population is infected. In the 

 intestine, and especially in the colon, a num- 



Cyst wall 



Food vacuole 

 containing 

 red blood ce 



Nuclei 



Chromatoid body 



Pseudopodium 



Cyst 



Trophozoite 



Figure 36. Entamoeba (formerly Endamoeba) histolytica, a human intestinal amoeba that 

 causes amoebic dysentery and amoebic liver abscess. Highly magnified. 



