MALARIAL FEVER. 451 



Malarial Fever. 



NATURE. — Formerly, malarial fever of man was regarded as a disease 

 produced by the bad air of certain unhealthy localities, s uch as swampy ground 

 in hot countries, Lavernan was the first to demonstrate the fact that the 

 cause of this disease is a very low form of animal life (the plasmodium of 

 Lavernan) which occurs in different forms, and which gains entrance into the 

 body by means of mosquitoes of the genus anopheles, that act as their carriers. 

 The malaria para,site is a protozoon, and not a plasmodium, which term, in 

 this application, is incorrect, though sanctioned by use. 



This parasite, in the form of very minute needle-shaped organisms, is injected 

 into our blood along with the saliva of the mosquito, at the moment this fly 

 bites our skin. Each of these spores (to adopt Professor Lankester's nomen- 

 clature) enters a red blood corpuscle, undergoes a stage of development (amoebula), 

 and breaks up into numerous spherical spores (enhflemospores) which enter the 

 blood by the destruction of the red corpuscle. They then envade and destroy 

 fresh red corpuscles and by their continued multiplication, infect the whole 

 of the blood. Other stages of development take place, until their final trans- 

 formation in the blood is attained. They are then in a suitable state to be 

 sucked up by mosquitoes, and after that takes place, they arrive in the stomach 

 of their carrier, undergo changes and migrations, and at last gain access into 

 the mosquito's salivary glands. They are then ready to make a new inva- 

 sion. We thus see that these organisms are parasites of the mosquito, as well 

 as of man ; and that a human being who is suffering from malarial fever can 

 infect the mosquitoes of a place which had hitherto been free from that disease. 

 In this way, one human being can indirectly infect another human being. 

 Direct infection from one man to another man can be communicated only by 

 inoculation. Mosquitoes have their regular meals, just after sunrise and after 

 sunset, which are consequently the times for specially avoiding these insects. 



The constitutional disturbance is chiefly due to the destruction of the red 

 corpuscles and to toxins elaborated by these parasites (Manson). 



" Observations by Koch, confirmed by Stephens and Christophers, have re- 

 cently shown that in intensely malarial districts, practically all the young 

 children have malaria parasites in their blood. As the native children get 

 older, their blood is progressively le? s liable to the infection, and in native 

 adults the parasites are rarely found. Immunity from malaria can there- 

 fore be acquired " (Manson). 



There are several forms of malarial fever, of which intermittent fever 

 (ague) and remittant or continued fever are the most common. The re- 

 searches of Majors Walter Reed and Gorgas and other observers show that a 

 moi^quito [ciilex fasciatus) is the transmitting agent of yellow fever. 



Dr. Manson points out that the successive generat'.ons of the parasites of 

 intermittent fever tend to become simultaneously mature in the blood of their 

 human host, about the same time every day, every second day, or every third 

 day, according to their species. Thus, those which live for 24 hours, produce 

 quotidian (daily) fever; those which ex^st for 48 hours, tertian fever; and those 

 whose cycle of development is 72 hours, quartan fever. I have not seen 

 similar paroxysms and remissions in the malarial fevers of horses. 



The bilio: s symptoms often seen in cases of malarial fever are chiefly due to 

 the bile of the patient containing an abnormally large amount of bilirubin, 

 which is the bile pigment that gives a yellow colour to the skin and other tissues 

 in jaundice. As bilirubin is produced by the decomposition of haemoglobin, it 

 follows that the more free haemoglobin there is in the blood, the greater will be 

 the quantity of bilirubin in the bile. In malarial fever the blood becomes loaded 

 with free haemoglobin, owing to the destruction of red corpuscles by the malarial 

 parasites. 



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