CHAPTER XXV 
MALARIA. THE TYPHUS FEVER 
Malaria 
The organism causing malaria was discovered by 
Laveran in 1880. There are three forms of malaria: 
tertian, when chills recur every forty-eight hours; quar¬ 
tan, when they recur every seventy-two hours; and 
sestivo-autumnal—more or less irregular. Each of these 
varieties is caused by a different parasite, the tertian by 
plasmodium vivax, the quartan by plasmodium malarioe, 
and the sestivo-autumnal by plasmodium falciparum. 
The aestivo-autumnal fever is the most dangerous of all 
forms, but is seldom met with in the temperate climate. 
The parasites are transmitted by mosquitoes, whose bite 
carries them into the human body where they pass 
through regular phases of development within the red 
blood cells, multiplying and breaking into numerous 
young forms, which are liberated into other red blood 
cells. When a mosquito bites a malarial patient he car¬ 
ries these young forms, which undergo the second cycle 
(sexual) of development within the stomach of the mos¬ 
quito, then new forms reach the salivary glands of the 
mosquito and are transmitted to human beings with the 
bite. 
In order to demonstrate the malarial parasite in the 
human blood, a blood smear is made on a glass slide or a 
cover-slip and is stained with Wright’s stain just as an 
ordinary blood preparation is made. The appearance of 
the parasites vary according to the variety and the stage 
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