158 PHARMACEUTICAL BACTERIOLOGY. 



cause of ague or malaria. The carriers of the infection are certain mosquitos 

 (species of Anopheles). If the Anopheles group of mosquito could be exter- 

 minated throughout the world, malaria would disappear also. The organism 

 is introduced into the blood by the sting of the insect. In the blood it un- 

 dergoes certain cycles of development. The fever paroxysms are due to the 

 sporulation of the organisms in the circulatory system. During the interval's 

 (non-sporulation) there is no marked febrile disturbance. There are several 

 species of Plasmodium causing the several forms of malaria. The benign 

 tertian (P. vivax) has a cycle of forty-eight hours; the quartan {P. malaricB) 

 has a cycle of seventy-two hours; and the malignant tertian (P . falciparum) 

 has a cycle of forty-eight hours. In the latter type the paroxysms are so severe 

 as to give rise to a continued fever. Quinine is fatal to the Plasmodium and 

 this remedy should be given as a prophylactic and as a cure. 



The draining of swamps and other breeding places for mosquitos has 

 reduced malaria. The use of mosquito netting, screens, etc., has also 

 checked this disease. Small water areas may be treated with crude petro- 

 leum oil which kills the mosquito larvae. 



The primary cause of yellow fever is as yet unknown but it has been def- 

 initely determined that the carrier is a mosquito, the Stegomyia calopus. 

 Yellow fever is essentially a tropical disease, though it may flourish in tem- 

 perate zones until checked by frost which is so readily fatal to the carrier, the 

 mosquito. It has been ascertained that the Stegomyia does not occur far 

 from human habitations, that it breeds generally in barrels and cisterns 

 containing rain water, rather than in ponds or larger bodies of water, more 

 remote from habitations. These discoveries have made possible a very 

 effectual campaign against this dread disease. The Federal Government 

 aided by State and Local Boards of Health have insisted on a discontinu- 

 ance of those breeding places which can be controlled easily. The larger 

 more public breeding places were covered with crude oil. Screening win- 

 dows and doors and sulphur or Pyrethrum fumigation of mosquito-infested 

 houses and rooms was insisted upon and individuals were instructed in 

 methods of self-protection against the bites of mosquitos. As a result the 

 yellow fever ravages are now reduced to a minimum. 



