Background
Lingering post-treatment parasite antigen in blood complicates malaria diagnosis through antigen detection. Characterization of antigen clearance dynamics is important for interpretation of positive antigen detection tests.
Conclusions
LDH and Aldo show substantially different clearance rates than HRP2, and their presence is largely indicative of active infection.
Results
We used a bead-based serological assay to measure lactate dehydrogenase (LDH), aldolase (Aldo), and histidine-rich protein 2 (HRP2) levels in 196 children with Plasmodium falciparum malaria treated with effective antimalarials and followed for 28 to 42 days as part of therapeutic efficacy studies in Angola. Compared to pre-treatment levels, antigen concentrations two days after treatment declined by 99.7% for LDH, 96.3% for Aldo, and 54.6% for HRP2. After Day 2, assuming a first-order kinetics clearance model, half-lives of the antigens were 1.8 days (95% CI: 1.5-2.3) for LDH, 3.2 days (95% CI: 3.0-3.4) for Aldo, and 4.8 days (95% CI: 4.7-4.9) for HRP2. Conclusions: LDH and Aldo show substantially different clearance rates than HRP2, and their presence is largely indicative of active infection.