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Ultrasensitive PCR used in low-transmission malaria-endemic settings has revealed a much higher burden of asymptomatic infections than that detected by rapid diagnostic tests (RDTs) or standard PCR, but there is limited evidence as to whether this is the case in higher transmission settings. Using dried blood spots (DBS) collected among 319 schoolchildren in Bagamoyo, Tanzania, we found good correlation (Pearson’s R = 0.995) between Plasmodium falciparum parasite densities detected by a DNA-based 18s rRNA real-time PCR (qPCR) and an RNA-based ultrasensitive reverse transcriptase (RT)-PCR (usPCR) for the same target. Whereas prevalence by usPCR was higher than that found by qPCR (37% versus 32%), the proportion of additionally detected low-density infections (median parasite density < 0.050 parasites/µL) represented an incremental increase. It remains unclear to what extent these low-density infections may contribute to the infectious reservoir in different malaria transmission settings.
Authors’ addresses: Christine F. Markwalter and Tonelia Mowatt, Duke Global Health Institute, Duke University, Durham, NC, E-mails: firstname.lastname@example.org and email@example.com. Billy Ngasala and Mwajabu Loya, Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania, E-mails: firstname.lastname@example.org and email@example.com. Christopher Basham, Zackary Park, Meredith Muller, and Jessica T. Lin, Division of Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC, E-mails: firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, and email@example.com. Christopher Plowe and Myaing Nyunt, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, E-mails: firstname.lastname@example.org and email@example.com.