Five mL of infected red blood cells were obtained from each patient. One mL was used to purify genomic DNA following standard methodologies. The remaining blood was processed to isolate total RNA using the Trizol reagent (Invitrogen) according to the manufacturers' instructions. A recently described magnetic method for the isolation of matures stages of malaria parasites was used to concentrate and purify P. vivax-infected reticulocytes [15] . Giemsa-stained smears showed an absence of human leukocytes, and all the reticulocytes were infected with mature stages of the parasite (Additional file 1). Eluents were centrifuged at 800 × g for 10 minutes, supernatants discarded, and pellets used to purify total RNA. The protocol for this study was approved by the Ethical Committee of Hospital Clinic and informed consent obtained from the patients.