MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 837 



an attack of ague on every fourth day and the disease produced 

 is called quartan fever. Patients infected by Plasmodium falci- 

 parum often have a quotidian fever with a daily rise in the temp- 

 erature, although a three day period may be recognized in some 

 cases. The disease is called aestivo-autumnal fever. There are 

 three stages in the paroxysm: during the chill, the patient feels 

 cold; in the hot stage he feels warm — his temperature is above 

 normal during both stages; in the sweating stage the temperature 

 falls to normal and the patient's discomfort becomes much less. 



The regularly recurring chills and fever constitute the only symp- 

 toms characteristic of malaria and a regular rise in temperature on the 

 third or fourth days of an illness is strongly suggestive of a malarial 

 infection. The tj^e of disease and the symptoms, produced by a 

 malarial infection, may vary almost indefinitely according to the pre- 

 cise way in which the host is harmed by the infection. Consequently, 

 an enumeration of the clinical manifestations of malaria is of less 

 importance to a student than is an understanding of the way in which 

 the malarial parasites harm their host. The malarial parasites de- 

 stroy the red cells and thus cause an anseniia with the symp- 

 toms which result from it. Secondly, they produce toxins which 

 may cause both acute and chronic intoxications. The acute 

 intoxications are seen in the elevation of body temperature and in 

 unconsciousness in some pernicious forms of malaria; malarial 

 neuritis is an example of chronic intoxication. Lastly, inalarial para- 

 sites may do harm by blocking the capillaries and causing the death 

 of the cells which are cut off from the circulation, the symptoms which 

 result depending upon the functions of the cells which are destroyed. 

 If the disease be long continued, with a high temperature, the de- 

 generative changes which usually result from chronic disease and 

 constant fever are-produced in the patient. 



The definite diagnosis of malarial fever depends upon the demon- 

 stration, in a patient, of the malarial parasite, or of the pigment pro- 

 duced by it. 



Quinine has a specific action on the malarial parasite and is the 

 most valuable drug available for the treatment of the disease. It must 

 be given in full doses and treatment continued until all parasites dis- 

 appear from the blood. 



Malaria, since it is of the type of disease which is produced by 



