Complement fixation in relapsing Plasmodium vivax malaria.

An unusual opportunity for study of complement fixation in relapsing Plasmodium vivax malaria, acquired in Pacific war areas, was afforded us at Kennedy General Hospital. We were able to follow the complement fixation reactions for malaria over a period of 6 months in a group of such patients, and to correlate the findings with coincident blood films and with clinical activity. These studies, which are described below, show that in relapsing vivax malaria:

Complement fixation is a more sensitive method of detecting persistent infection than is the examination of a coincident thick blood film.
Complement fixation is an expression of infection, and is directly related to existent or recent parasitemia, which may, or may not, have been of sufficient level to produce a clinical attack.
A consistently positive complement fixation for malaria continuing for more than 2 months is highly indicative of eventual relapse.