Rapid Diagnostic Tests for Malaria
Malaria rapid diagnostic tests (RDTs) are increasingly used as a tool for the diagnosis of malaria, both in endemic and in non-endemic settings. Microscopy remains the cornerstone of diagnosis, but RDTs to detect Plasmodium-specific antigens (proteins) in whole blood of infected people have emerged as an attractive alternative where high quality microscopy is not available.
RDTs detect Plasmodium parasites in blood by antibody-antigen reactions on a nitrocellulose strip, which become visible as cherry-red lines. Different formats exist: two-band RDTs are mostly designed to detect Plasmodium falciparum. They display a control line and a test line, which targets either histidine-rich protein-2 (HRP-2) or P. falciparum-specific parasite lactate dehydrogenase (Pf-pLDH). Three- and four-band RDTs display a control line and two or three test lines, one targeting a P. falciparum specific antigen, a second line targeting antigens common to the four species, such as pan-Plasmodium-specific lactate parasite dehydrogenase (pan-pLDH) or aldolase, and in case of the four band RDTs, a third line which targets Plasmodium vivax-specific pLDH (Pv-pLDH).
EQA scheme run by UKNEQAS Parasitology is comprised of 2 distributions per annum with 2 samples included in each distribution. 500 microlitres of freeze dried positive or negative blood samples are sent to participants of the scheme. Participants are instructed to resuspend the freeze dried analyte in 500 microlitres of sterile water and carry out their usual clinical protocol for RDT analyses.