title: Sensitive and accurate quantification of human malaria parasites using droplet digital PCR (ddPCR).
abstract: Accurate quantification of parasite density in the human host is essential for understanding the biology and pathology of malaria. Semi-quantitative molecular methods are widely applied, but the need for an external standard curve makes it difficult to compare parasite density estimates across studies. Droplet digital PCR (ddPCR) allows direct quantification without the need for a standard curve. ddPCR was used to diagnose and quantify P. falciparum and P. vivax in clinical patients as well as in asymptomatic samples. ddPCR yielded highly reproducible measurements across the range of parasite densities observed in humans, and showed higher sensitivity than qPCR to diagnose P. falciparum, and equal sensitivity for P. vivax. Correspondence in quantification was very high (>0.95) between qPCR and ddPCR. Quantification between technical replicates by ddPCR differed 1.5-1.7-fold, compared to 2.4-6.2-fold by qPCR. ddPCR facilitates parasite quantification for studies where absolute densities are required, and will increase comparability of results reported from different laboratories.
authors.affiliation: Walter &Eliza Hall Institute, Parkville, Australia.|Department of Medical Biology, University of Melbourne, Parkville, Australia.
authors.forename: Cristian
authors.initials: C
authors.lastname: Koepfli
authors.affiliation: Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Wang
authors.initials: W
authors.lastname: Nguitragool
authors.affiliation: Swiss Tropical and Public Health Institute, Basel, Switzerland.|University of Basel, Basel, Switzerland.
authors.forename: Natalie E
authors.initials: NE
authors.lastname: Hofmann
authors.affiliation: Walter &Eliza Hall Institute, Parkville, Australia.|Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea.
authors.forename: Leanne J
authors.initials: LJ
authors.lastname: Robinson
authors.affiliation: Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea.
authors.forename: Maria
authors.initials: M
authors.lastname: Ome-Kaius
authors.affiliation: Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Jetsumon
authors.initials: J
authors.lastname: Sattabongkot
authors.affiliation: Swiss Tropical and Public Health Institute, Basel, Switzerland.|University of Basel, Basel, Switzerland.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Felger
authors.affiliation: Walter &Eliza Hall Institute, Parkville, Australia.|Department of Medical Biology, University of Melbourne, Parkville, Australia.|Institut Pasteur, Paris, France.
authors.forename: Ivo
authors.initials: I
authors.lastname: Mueller
mesh_terms: D016054:DNA, Protozoan / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D008288:Malaria / Q000175:diagnosis* / Q000469:parasitology; D008853:Microscopy; D010963:Plasmodium falciparum / Q000235:genetics* / Q000302:isolation & purification; D010966:Plasmodium vivax / Q000235:genetics* / Q000302:isolation & purification; D012337:RNA, Ribosomal, 18S / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D016054:DNA, Protozoan; D012337:RNA, Ribosomal, 18S