That an increase in the MSP-1 antibody level is a reliable indicator even for low-level blood-stage exposure following B-cell priming, in this case by CPS-immunization, was illustrated strikingly in our study: 1 volunteer (classified as protected on the basis of the absence of parasitized erythrocytes on a thick blood smear) was retrospectively shown by qPCR to have had subpatent blood-stage parasitemia [13]. This evidence concerns the gene ATAD1 and parasitic infectious disease.