ENLARGED SPLEENS AND MALARIA 
181 
In the malarial countries in which I have worked, though there has been a 
seasonal variation, there has been no period during which fresh infections have not 
occurred. 
As a test for the prevalence of malaria, the ' spleen test ' may be worse than 
useless unless race and age are taken into account. In Africa, if examination be made 
of persons five to fifteen years of age, the least healthy districts would appear to be 
the least malarial, judged by the proportion of enlarged spleens. If adult natives 
alone were examined all districts would appear to be free from malaria. 
In South America malaria would appear to be rare or common in a district 
according to the race, Negro or Indian, examined. 
Even in a country with a population of uniform race, examined at an age 
at which splenic enlargement is most common, we known too little of the other factors 
causing enlargement of the spleen for the test to be at all an accurate one. 
It must always be remembered that even such characteristic sequelae of 
diseases as neuritis after diphtheria, nephritis after scarlatina, and organic cardiac 
valvular disease after rheumatism, and even stricture after gonorrhoea are dependent 
on other factors as well as on the primary disease ; and the frequency of the sequela 
would afford no real measure of the prevalence of the primary disease. Excluding 
the factors, race and age, splenic enlargement can be considered as a rough inaccurate 
measure of the prevalence of malaria, but still a useful one. 
