CONTKOL <>r ANIMAL I'A l; ASlTKS 2nT 



from 40^ north latitude to IfP south, — ifUfh-rint; uuinv «•! the most 



fertile vall«\vs uniuhahituMe. Manson doclares that lualarial parasites 

 cause more death, an<l more )»redisposition to death fn»m other causes, 

 than all other human parasites taken to.t;»'th«'r. Howard estimated 

 (in 1900) that they caused :),()0<),()00 cases of uialaria and nearly 

 l"i,000 deaths annually in the United States, and actually imposed a 

 vearlv tax upon this country of not less thau $l(M),()(i(),0(M). 



The malarial i>arasite is carried to man l»y the bite of an anopheline 

 mosquito. The minute vcrniicitles, or sjntntzoites, i^nU'v the red corpuscles 

 and p-ow until the substance of the corpuscles is absorbed, when they 

 divide asexually into, generally, from 1(5 to 24 spores, inerozoifrs. These 

 burst out of the corpuscles, and this, probably on account of their 

 poisonous waste pro<lucts set free iu the blood, causes the "chill.'" 

 While thus unprotected in the Idood [>lasuui the para.sites of our com- 

 mon, temperate-zone malarias (/'. n'vax and /'. nKihiritc) may be killed 

 by heavy doses of (juinine. The i)arasites of the nuili.^nant malarias of 

 the tropics are not aifected by this drug. ( )iir common malaria is caused 

 by P. vivax, which passes through its life cycle in the blood every forty- 

 eitrht hours — the usual time between chills. This is also known as 

 tertian malaria. (Quartan malaria, the other temperate-zone type <»f 

 the disease, caused by /'. iii<ilari(i\ which requires seventy-two hours 

 to complete its life cycle, is (diaracterized by chills every third day. 

 Some authorities distinguish two types of malignant tropical malaria, 

 the (piotidian, in which the parasite conqdetes its asexual life cycle 

 in twenty-four hours, and the tropical tertian, in which the cycle is 

 forty-eight hours. All these para.sites multii>ly sexually within the 

 anopheline mosquitoes. 



Kea.soning from the above data, we see that there are thre«' ways by 

 whieh malaria may be banished from a locality: 1. Exterminate the 

 mosquitoes (see Chapter XI). 2. Prevent the mosipiitoes from biting 

 healthy i)eople. :{. Prevent mosquitoes friuu becoming infected by 

 lilting malarial patients. As soon as every responsible member of 

 any community beconu^s able to grasjt these sinq>le facts, that lom- 

 munitv mav free it.self completelv from the most vicious blood parasites 

 that afflict mankind. 



The Piroplasmas ; Texas fever, or bovine malaria. While the cattle 

 tick acts as carri»'r, the parasite of Texas fever is I'lmj^lasina (Latin 

 pints, '^a pear") hlffcnilnitm, which attacks the red blood cells of cattle. 

 Tick extermination is banishing this costly jiarasite from our South- 

 ern states (see Chajiter XV). Horses, sheep, dogs, and other animals 



