MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 893 



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, malarial 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 depend 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. 



40 





FIG. 190. Longitudinal section of Anopheles. A, head; B, thorax; C, abdomen; 

 i, oesophagus; 2, salivary glands; 3, dorsal reservoir; 4, ventral reservoir; 5, canal 

 entering stomach; 6, stomach; 7, malpighian tubes; 8, hind-gut; 9, rectum; TO, wings; 

 n, legs. (After Grass I, from Lang and Doflein.) 



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 promptly in full doses. Treatment must be continued until 

 all parasites disappear from the blood. 



Malaria, since it is a disease which is caused by a parasite and 

 transmitted by an insect, may be prevented by measures directed 

 either against the parasite or against the transmitting agent. 

 Malaria is caused by a Plasmodium and transmitted by the bites of 

 mosquitoes belonging to the Anophelina. The disease may be com- 



