TERTIAN FEVERS 



1161 



III. THE TERTIAN FEVERS. 



Tertian malarial fever depends for its symptoms and course upon 

 the life-history of Plasmodium vivax, introduced into the blood of 

 man by an anopheline mosquito. Its clinical course will depend 

 entirely upon whether the parasites are of approximately the same 

 age or whether they have been introduced into the body on different 

 days. 



If only parasites of approximately one age exist in the blood, 

 a typical simple tertian malarial fever ensues, with an interval of 

 forty-eight hours (the length of time which a merozoite takes to 

 become a fully developed schizont). Such a fever is called ' tertiana 

 simplex,' or simple tertian fever. 



If the parasites belong to two distinct broods, or have been intro- 

 duced on two different days, and are therefore of different ages, 

 the patient will develop fever every day. Such a fever would be 

 quotidian in type, and would be called ' tertiana duplex,' or double 

 tertian fever. 



If many broods of parasites are present, the fever becomes sub- 

 continuous and irregular. 

 There are, therefore, several types of tertian fevers — viz. : — • 



A. Acute tertian malaria : — 



1. Simple tertian fever. 



2. Double or quotidian tertian fever. 



3. Irregular subcontinuous tertian fevers. 



4. Mixed infections. 



B. Chronic tertian malaria. 



Simple Tertian Fever. 



Definition. — Simple tertian malaria is characterized by attacks 

 of fever recurring every forty-eight hours, and separated by apy- 

 rexial intervals which occupy the time required by Plasmodium 

 vivax to pass from the merozoite to the fully developed schizont. 



Incubation, — The natural incubation period is believed to be 

 from eight days upwards. The period of incubation in experi- 

 mental cases in which quantities of infected blood were inoculated 

 varied from four to twenty-two days. The period of incubation 

 after the experimental bites of infected anophelines varies from 

 seven to twenty-five days. 



Remarks. — The clinical description may be divided into — (i) the 

 attack of fever; (2) the apyrexial interval. 



The Attack of Fever, — -There may be no prodromata, or, on the 

 other hand, these may be most characteristic. When present, 

 they take the form of pain in the head and the back, and especially 

 in the bones of the limbs — more particularly the joints — which lead 

 to their being considered to be rheumatic, together with a feeling 

 of lassitude and illness. On the day succeeding these sensations 

 the patient may feel quite well, but on the next day they may recur. 



