DISEASES CAUSED BY H^MOSPORIDIA 33 



country, and the course of rivers or their estuaries. 

 Elevation has a decided effect in temperate regions, but 

 in equatorial districts malaria may be still common 4,000 

 or 5,000 ft. above the sea. 



The topographical distribution of malaria is affected by 

 many conditions, such as density of population, but is 

 mainly determined by the species of mosquito present, 

 and the abundance of suitable breeding places for such 

 mosquitoes. 



CLINICAL VARIETIES OF MALARIA, AND SPECIES 

 ASSOCIATED WITH THESE VARIETIES. 



Benign tertian ; Tertian Fever. Geographical Distribu- 

 tion. It occurs in all the malarial tropical countries, 

 but is rarer in Africa than in the East. In subtropical 

 and temperate countries a larger proportion of the cases 

 are benign tertian, and it occurs further north than the 

 other forms of malaria. It used to be common in some 

 parts of Great Britain and, rarely, cases still occur. 



The clinical course of an attack of benign tertian 

 malaria is regular, though in a first attack of a severe 

 type the periodicity may not be well marked. The 

 attacks of pyrexia are short, lasting some six or eight 

 hours. The temperature rises suddenly, and there is a 

 rigor, often so severe that the bed on which the patient 

 is lying is shaken. 



The temperature often rises to 105 F., or more, and 

 the pulse is quick and bounding. The urine presents the 

 usual febrile characters. The skin is cold and the features 

 pinched, whilst the lips may have a bluish tinge. 

 Following the cold stage is the hot stage, and during 

 this the patient still has fever, usually high, severe head- 

 ache, and the skin is dry. This stage may last for two 

 or three hours, and is succeeded by a sweating stage 

 during which the temperature rapidly falls. With the 

 onset of the diaphoresis the patient becomes much more 

 comfortable, and the temperature rapidly falls to or 



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