Abstract
BackgroundRapid diagnostic test (RDT) positivity is supplanting microscopy as the standard measure of malaria burden at the population level. However, there is currently no standard for externally validating RDT results from field surveys.MethodsIndividuals’ blood concentration of the Plasmodium falciparum histidine rich protein 2 (HRP2) protein were compared to results of HRP2-detecting RDTs in participants from field surveys in Angola, Mozambique, Haiti, and Senegal. A logistic regression model was used to estimate the HRP2 concentrations corresponding to the 50 and 90% level of detection (LOD) specific for each survey.ResultsThere was a sigmoidal dose–response relationship between HRP2 concentration and RDT positivity for all surveys. Variation was noted in estimates for field RDT sensitivity, with the 50% LOD ranging between 0.076 and 6.1 ng/mL and the 90% LOD ranging between 1.1 and 53 ng/mL. Surveys conducted in two different provinces of Angola using the same brand of RDT and same study methodology showed a threefold difference in LOD.ConclusionsMeasures of malaria prevalence estimated using population RDT positivity should be interpreted in the context of potentially large variation in RDT LODs between, and even within, surveys. Surveys based on RDT positivity would benefit from external validation of field RDT results by comparing RDT positivity and antigen concentration.
Highlights
Rapid diagnostic test (RDT) positivity is supplanting microscopy as the standard measure of malaria burden at the population level
A total of 8184 individuals from six surveys were given a histidine rich protein 2 (HRP2)-based RDT and had their blood sample quantified for HRP2 concentration
The relationship between RDT positivity and log10 HRP2 concentration was sigmoidal in all six surveys, and a logistic dose–response model provided a good fit for all datasets (Fig. 1)
Summary
Rapid diagnostic test (RDT) positivity is supplanting microscopy as the standard measure of malaria burden at the population level. HRP2-based RDTs are assessed against a panel of well-characterized culture-derived P. falciparum strains and wild isolates collected from several malaria endemic countries and diluted to 200 and 2000 parasites/ μL for which HRP2 protein concentrations are known. These data quantifying HRP2 content of the panel samples are used primarily to standardize year to year sample set composition leaving parasite density as the primary sample characteristic. Product specificity determination involves testing products on multiple known HRP2 negative blood samples, including samples containing molecules or antibodies that could cross-react with the test reagents on the RDT filter strip, potentially providing false-positive results [8]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
