Malaria Rapid Diagnostic Test Sensitivity Drops in Specific Malawian Patient Subgroups

Malaria rapid diagnostic tests demonstrated substantial variation in diagnostic performance across distinct patient subgroups in rural Malawi, with sensitivity dropping markedly among young infants and adults. In an evaluation conducted across rural health centers between 2019 and 2021, investigators evaluated how well point-of-care rapid diagnostic tests detected Plasmodium falciparum in comparison to quantitative polymerase chain reaction assays. The study, authored by Geoffrey Guenther, Alick Sixpence, Charles Mangani, Alfred Matengeni, Jaroslaw Harezlak, Don P. Mathanga, Terrie E. Taylor, Miriam K. Laufer, Karl B. Seydel, Lauren M. Cohee, and Clarissa Valim, examined 1,108 patient visits to identify specific groups where test accuracy decreased, with the broader goal of improving rapid test-based clinical diagnosis.

Across the 1,108 patient visits analyzed, approximately 48 percent of quantitative polymerase chain reaction tests and 37 percent of malaria rapid diagnostic tests were positive for infection. Overall, the fraction of positive rapid tests among patients confirmed positive by quantitative polymerase chain reaction, measuring sensitivity, was 67 percent. In contrast, the fraction of negative rapid tests among participants confirmed negative by quantitative polymerase chain reaction, defining test specificity, was 91 percent across the study population.

The sensitivity of the rapid diagnostic tests fluctuated widely depending on the age of the patient. The lowest test sensitivity occurred among adults aged 25 to 40 years, where it reached only 38 percent, and among infants younger than one year of age, where sensitivity was 33 percent. Conversely, the diagnostic tests achieved their highest sensitivity of 86 percent among children aged 5 to 8 years. When examining discordant results where the rapid diagnostic test was negative but the quantitative polymerase chain reaction was positive, nearly all false-negative cases showed parasite densities below 200 parasites per microliter of blood.

Statistical regression models showed that male sex, younger age, and the clinical presence of symptoms including fever, headache, chills, and vomiting were associated with a reduced likelihood of obtaining a false-negative rapid test result. However, the presence of those same clinical symptoms—fever, headache, chills, and vomiting—made the occurrence of a false-positive rapid diagnostic test result more likely. Using classification tree analysis, researchers determined that combining clinical and demographic characteristics predicted true positive rapid test results with 79 percent overall accuracy and true negative results with 84 percent overall accuracy.

The researchers noted that patient age and parasite density were negatively correlated in the study population. Because a patient’s age is readily available to clinicians during point-of-care medical encounters, age was included in the regression models and classification trees rather than parasite density. Although the authors outlined several potential explanations for discordance between quantitative polymerase chain reaction and rapid diagnostic tests, such as incidental malaria infections, they concluded that identifying subgroups where test performance is reduced can help guide the deployment and ongoing development of rapid tests in clinical care and malaria surveillance.

Subject of Research: Subgroup performance of malaria rapid diagnostic tests in Malawi

Article Title: Identifying subgroups with decreased performance on malaria rapid diagnostic tests in Malawi

Article References: Guenther, G., Sixpence, A., Mangani, C., Matengeni, A., Harezlak, J., Mathanga, D. P., Taylor, T. E., Laufer, M. K., Seydel, K. B., Cohee, L. M., & Valim, C. (2026). Identifying subgroups with decreased performance on malaria rapid diagnostic tests in Malawi. PLOS Global Public Health, 6(11), e0007366. https://doi.org/10.1371/journal.pgph.0007366

Image Credits: AI Generated

DOI: 10.1371/journal.pgph.0007366

Keywords: malaria, Plasmodium falciparum, rapid diagnostic tests, quantitative PCR, Malawi, diagnostic sensitivity, diagnostic specificity, parasite density, rural health centers, classification tree analysis, false negative results, false positive results, malaria surveillance, patient age, point-of-care testing, regression models