PLASMODIUM DANILEWSKYI 



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They begin as small forms, with a central nucleus but no vacuole, 

 and soon become pigmented, the fully-grown macrogametocyte 

 being a little larger than a normal corpuscle. Its dark cytoplasm is 

 heavily pigmented, especially at the periphery, at Which the nucleus 

 is also placed. The corpuscle forms but a small rim around the 

 parasite. 



The microgametocyte shows the usual structure already described, 

 but is less pigmented, and has a clearer cytoplasm. The corpuscle 

 is not enlarged, as in the case of the macrogametocyte, and much 

 more of it is visible around the parasite. The formation of the 

 microgametes has been observed, but the infection of the mosquito 

 is difficult to bring about, though the development in the mosquito 

 has been traced by Bignami and Bastianelli. The oocyst is charac- 

 terized by the pigment, which is black, coarse, and gathered into a 

 clump. The cycle of development is the same as in P. vivax, but 

 takes about eighteen to twenty-one days to be completed after 

 infection in mosquitoes which were kept at a temperature of about 

 22° C. This appears to be the degree of heat at Which the process 

 takes place best. At the end of that time the completely developed 

 sporozoites can be seen. 



Pathogenicity. — Causes quartan fever. 



Plasmodium tenue Stephens, 191 4, is an extremely amoeboid form, with 

 scanty cytoplasm and much chromatin, found first in blood-films from India, 

 but known also in Africa, It may be Laverania malaries. Plasmodium 

 caucasicum Marzinowsky, 191 6, found on the Black Sea littoral, may also be 

 Laverania malarice. 



Plasmodium danilewskyi Grassi and Feletti, 1890. 



Synonyms. — Laverania danilewskyi Grassi and Feletti, 1890; Hcemamoeha 

 relicta Grassi and Feletti, 1891 ; Cytosporon malaricB avium Danilewskyi, 1891 ; 

 Proteosoma grassii Labbe, 1894; Plasmodium relictum Sergent, 1907. 



This parasite was discovered by Grassi in the blood of birds in Italy, and 

 causes death in partridges in Hungary. It affects sparrows in India, and is 

 the form in which Ross first traced the development of a Plasmodium in a 

 mosquito. It occurs in Ceylon, and is common in Africa. 



The young trophozoite becomes pigmented, and, displacing the nucleus, 

 grows into the schizont, which forms about nine merozoites. 



The macrogametocyte has but little chromatin in its nucleus, which is 

 rounded, while the microgametocyte has an elongated, darkly - staining 

 nucleus. 



These develop in Culex fatigans, C. nemovosus, or some other species, when 

 in about twelve to fifteen hours ookinetes are seen, and in about one to two 

 days well- developed oocysts are present in the stomach in the form of round, 

 transparent cysts, with haemozoin scattered through them. 



In three to four days the oocysts have increased in size, and sporoblasts 

 have appeared, and even sporozoites are forming. 



In nine to ten days the oocyst has become fully developed and bursts, 

 and the sporozoites can first be seen in the muscles of the thorax, and then in 

 the salivary glands, in which they lie principally in the central or poison lobe. 

 The black spores already mentioned can be noted in the stomach, and, accord- 

 ing to Stephens and Christophers, in either the thoracic muscles or in the 

 salivary glands. 



No traces of parasites have been found in the larvae or second generation of 

 Culex. 



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