266 



is not low. In others, especially in African bush 

 stations, the percentage may reach fifty per 

 cent. 



3. Leave specimens not dissected for several 

 days and examine the mid-gut for zygotes. 



-Malarial Infection of Europeans 



Although malaria is an infectious disease, 

 and can arise only from an original human 

 source, yet in the tropics we can no longer con- 

 sider the origin of infection as occasional and due 

 to the presence of other cases of 'fever.' In the 

 tropics, and especially in Africa, we are dealing 

 with a disease which is a normal condition of 

 childhood, and which, with the coincident infec- 

 tion of Anophelines, is the usual accompaniment of 

 every native hut. 



European malaria in the tropics is, indeed, 

 chiefly dependent on two factors — 



1. The degree of exposure to native malaria, 

 i.e., the proximity to native dwellings. 



2. The endemic index of the native dwel- 

 lings in question. 



To Investigate European Malaria 



I. Examine the blood of as many Europeans 

 as possible. Enquire carefully whether the person 

 is taking quinine at the time, also take the 

 temperature. 



(i) The number shewing parasites or cres- 

 cents. 



(ii) The presence of pigmented leucocytes. 



(iii) The presence of an increase of the large 

 mononuclear leucocytes. 



