ENDEMIC INDEX IN MALARIA 85 



The period mentioned includes the period of incuba- 

 tion, usually ten to fourteen days. The first attack of 

 fever is usually a severe one, but it must be remembered 

 that many Europeans are inclined in a malarial country 

 to call any illness from which they suffer " fever." This 

 reduces to a small extent the value of the method. 



(D) The proportion of bodies showing past or present 

 evidence of malaria in the shape of malarial pigment 

 deposits is only of value in places where post-mortem 

 examinations can be made (fig. 27). 



FIG. 27.- 



-Negroes (native Africans), compiled from post-mortem 



examinations in British Guiana, 1893-1895. The line commences at one 

 month, no pigmentation being found earlier. The next point is " under six 

 months." 



(E) The number of anophelines, especially of those 

 belonging to species known to carry malaria, is of great 

 importance. A large number indicates the possibility of 

 a high endemic index in the place, if sufficient oppor- 

 tunities for the infection of these mosquitoes exist. If 

 the proportion of the anophelines found to be infected 

 is large it indicates a high endemic index : but the 

 absence of infected mosquitoes, even when a large 

 number are examined, especially of the mosquitoes 

 caught in European houses, is quite compatible with 

 a high endemic index. In fact this test is a better 



