LAVE RAN I A MALARIA 



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tion, there is also a great difference in the time occupied by the cycle 

 of schizogony. Plasmodium malaricB requires seventy-two hours 

 to complete its schizogony, or, in other words, it will liberate its 

 toxins and cause an attack of fever in its human victim every 

 seventy-two hours, while in an infection with only one brood of 

 parasites the intervening period will be without fever. This inter- 

 mission is so marked that it was noted by the ancients, and formed 

 one of their types of intermittent fever, and as the attack of fever 

 occurred on the fourth day, after an interval of seventy-two hours, 

 it was called a ' quartan,' or fourth-day fever, and as such is clearly 

 described by Hippocrates. Plasmodium vivax requires forty-eight 

 hours to complete its schizogony, and in single infections pro- 

 duces fever every forty-eight hours — i.e., on the third day — and 

 therefore this type of fever is called ' tertian.' 



Laverania malaricB, on the other hand, does not appear to be so 

 regular in the time of its schizogony, and may require from thirty- 

 six to forty-eight hours for the purpose; but though typically pro- 

 ducing a tertian fever, the effects due to its sporulation in the organs 

 are much more severe and protracted than those produced by 

 P. vivax. Clinically, therefore, there are two types of tertian 

 malarial fever — -a benign and a malignant. The former, caused by 

 P. vivax, is generally called ' tertian malarial fever,' while the latter, 

 caused by L. malarice, is called ' subtertian malarial fever,' or 

 malignant tertian. 



In addition to these clearly defined parasites, others have been described 

 by various authors, and have been named HcBmamoeha prcBCOX and H. immacu- 

 lata by Grassi and Feletti. The former was said to be pigmented, and the 

 latter to be unpigmented. These parasites require only twenty-four hours 

 for the completion of the cycle of schizogony; consequently they cause fever 

 every twenty-four hours, which is therefore of the nature of a ' quotidian 

 malarial fever.' Many authorities, with whom we agree, consider these 

 parasites to be only stages in the development of Laverania malaricB. Quoti- 

 dian fever can be produced by three broods of P. malaricB, or two of P. vivax 

 or L. malavicB, and does not require a special quotidian parasite. Plasmodium 

 tenue Stephens, 191 3, appears in part to be related to P. vivax and in part to 

 L. malavicB, while P. vivax minutum of Emin, P. falciparum quotidianum of 

 Craig and Oswald© Cruz's parasite require confirmation. 



Therefore, there are only three parasites and three classes of fever 

 to be considered — viz. : (i) Plasmodium malaricB, causing quartan 

 malarial fever; (2) P. vivax, causing tertian malarial fever; 

 (3) Laverania malarice, causing subtertian malarial fever. 



2. The Mosquito. — With regard to the Anopheiinae, we know posi- 

 tively that some can carry the germ, while others cannot (see p. 883) . 

 Further, it appears quite evident that Culex and Stegomyia are 

 not carriers of malaria. Daniels, as we have already stated, is 

 inclined to suspect the iEdinae as being possible disseminators of 

 malaria in jungles, but there is no complete proof of this. Therefore 

 we have at present only the Anopheiinae to consider. 



For the various species of the Anopheiinae which are more or less definitely 

 known to carry malaria see Chapter XXXV., p. 883. 



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