The Plasmodium falciparum parasite is responsible for a vast majority of the world's malaria burden and can cause severe malaria that often leads to death. Interestingly, individuals who possess the sickle-cell trait hemoglobin genotype are protected from severe malaria caused by P. falciparum. The biological mechanisms that confer this protection are not completely understood. Using both in vitro time series samples and in vivo clinical samples from Malian children, we used quantitative PCR methods to measure the expression levels of the parasitic gene Cyclophilin 19B to study its potential association with the protective phenotype conferred by the sickle-trait hemoglobin genotype.