58 DISEASES DUE TO PROTOZOA 



resting stage, elongated, and situated peripherally in the pre-division 

 stage. 



The smaller mass is the muco-nucleus or blepharoplast, a short 

 rod, perpendicular or at a tangent to the nucleus. 



The parasite multiplies by simple fission, the nuclear masses always 

 elongating and dividing before the protoplasm. 



The parasites are almost always intracellular in man. 



Their growth and multiplication within the cell causes the cell to 

 enlarge and disrupt ; these parasites set free enter other endothelial 

 cells or are engulfed by leucocytes in which they may be seen in the 

 peripheral circulation. Clusters of them may be seen, 50 — 200, in 

 a structureless matrix debris of the host cells. 



In cultures the parasite enlarges rapidly, becomes elongated, and 

 acquires a flagellum at its rounded end acquired from the blepharoplast, 

 the whole measuring 12 — 20 /x in length. 



Attempts to transmit the parasite to vertebrates have failed. 



The parasite can be cultured from the blood, even during apyrexial 

 periods, on N.N.N, media. Ten or twelve tubes of this media should 

 be inoculated, otherwise parasites, if scanty, may not be secured. 

 Eight out of ten tubes may be negative. It is the flagellate form of 

 the parasite that develops in the cultures (Cornwall and Menon). 



Run a few drops of finger blood into 15 — 20 c.c. of citrated saline 

 solution, centrifuge it, inoculate N.N.N, media with the deposit of 

 corpuscles. 



Donovan believes that a biting insect carries it to man, while 

 Manson suggests that insects might deposit it upon (he wounded and 

 abraded surfaces of man. 



Once in the body it enters an endothelial cell of a capillary blood- 

 vessel or lymphatic, and therein grows and multiplies until up to 220 

 may be seen in one cell (Leishman). 



The liver, spleen, bone marrow and hmphatic glands may be thus 

 affected, less so the pancreas, kidneys, suprarenals, testicles and lungs. 



The enclosing cell ruptures, the liberated parasites are taken up by 

 leucocytes, polymorphonuclears, mononuclears, and rarely eosino- 

 philes, as a result of which process the parasites appear in the peripheral 

 circulation, especially if a diarrhoea due to intestinal ulcers increases 

 the polvmorphonuclears. 



The further development takes place in ihe bug, but ihe complete 

 life-cycle has still to be ascertained. 



INCUBATION. 



Not yet ascertained. 



One case was under ten days. 



It is generalh' considered lo be from (liree ^\•epK's lo sp\eral months. 



