This is essentially a laboratory study that is an addendum to an ongoing prospective Phase 4 multicenter observational study titled: Safety and Efficacy of Artesunate in Pregnant Women and Infants (ARTEMUM) being conducted in France. Infants, the parents of whom provided consent to have data collected from their child as part of the ARTEMUM study, will have an additional blood sample collected when other standard of care blood specimens are collected during the 2-day period after the start of intravenous (IV) artesunate treatment. A maximum of 4 samples will be taken and plasma will be isolated and stored frozen until analysis for plasma artesunate and dihydroartemisinin (DHA) concentrations. Red blood cells will also be frozen for further analysis (for example Kelch-13 mutations). In addition, a standard of care blood sample will be collected approximately one month post treatment for clinical laboratory tests.