In the classification of malarial diseases our purpose is to separate the actual disease from its sequelae. Our considerations, therefore, will concern the fully developed infection.
All who have attempted such a classification have found the way paved with difficulties, and but few have been able to combine the necessary conciseness with completeness. Until very recently the type of fever and the clinical symptoms were employed as the base of classification, and depending on whether one or the other factor was regarded as the more important, the scheme of classification differed.
Laveran's discovery of the parasites and Golgi's demonstration of the different species have laid for us a foundation for a rational classification. Yet such a division is possible only if definite clinical symptoms correspond to the different species of parasites. In our experience this clinical requirement is present and we can, therefore, abandon the old classifications and replace them by one constructed on a parasitologic basis. Moreover, we will see that even while adhering to this etiologic point of view, the clinical syndrome will not be neglected; on the contrary, the clinical symptoms will be allowed to influence the division of details.
Corresponding to the parasites, we divide malarial fevers into two principal groups:
II. Fevers produced by crescent forming parasites. To which we add:
III. Fevers produced by an association of both species of parasites (mixed infections).
IV. Latent fevers.*
* It is evident that in preserving the group "latent fevers" we have deviated from the pure etiologic classification in order to meet the clinical requirements. Blood examinations of latent fevers are as yet too few to make it possible to omit this group bv combining it with the others.