Plasmodium vivax molecular diagnostics in community surveys: pitfalls and solutions

• Published in: Malaria Journal
• Main Authors: Maria Gruenberg, Clara Antunes Moniz, Natalie Ellen Hofmann, Rahel Wampfler, Cristian Koepfli, Ivo Mueller, Wuelton Marcelo Monteiro, Marcus Lacerda, Gisely Cardoso de Melo, Andrea Kuehn, Andre M. Siqueira, Ingrid Felger
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2018
• Subjects: Plasmodium vivax; Surveillance; Molecular diagnostics; Mitochondrial DNA; 18S rRNA transcripts; LAMP; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/s12936-018-2201-0; https://doaj.org/article/0bbe20d755cc4a55bfbea32bbbae9534

Abstract A distinctive feature of Plasmodium vivax infections is the overall low parasite density in peripheral blood. Thus, identifying asymptomatic infected individuals in endemic communities requires diagnostic tests with high sensitivity. The detection limits of molecular diagnostic tests are primarily defined by the volume of blood analysed and by the copy number of the amplified molecular marker serving as the template for amplification. By using mitochondrial DNA as the multi-copy template, the detection limit can be improved more than tenfold, compared to standard 18S rRNA targets, thereby allowing detection of lower parasite densities. In a very low transmission area in Brazil, application of a mitochondrial DNA-based assay increased prevalence from 4.9 to 6.5%. The usefulness of molecular tests in malaria epidemiological studies is widely recognized, especially when precise prevalence rates are desired. Of concern, however, is the challenge of demonstrating test accuracy and quality control for samples with very low parasite densities. In this case, chance effects in template distribution around the detection limit constrain reproducibility. Rigorous assessment of false positive and false negative test results is, therefore, required to prevent over- or under-estimation of parasite prevalence in epidemiological studies or when monitoring interventions.