Rapid diagnostic tests (RDTs)
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| Overview |
RDTs detect antigens derived from malaria parasites in the blood of infected individuals. Precise formats differ according to manufacturer and purpose, but the simplest format (with a single test and control line) is shown below.
Essentially, a lysis buffer will be introduced to the test through one window (B on the image); a sample of blood is introduced into a second window (S). The interaction between buffer and sample will breakdown the red cells; this lysed sample they will diffuse along the strip where labelled antibodies will be used to detect the presence of parasites, forming a visible band in one or more test windows (T). Successful test performance will be shown by the appearance of a control band (C).
| The antigens used by the tests (click links for details) |
The antigens detected by an RDT vary according to the purpose of the test and manufacturers choice. The antigens detected by the tests fall into two groups, but each antigen has strengths and limitations, so it is important to understand which antigens your test uses (see links). 1. “Species-specific antigens”. These detect specific malaria species: a. Histidine-rich protein 2 (HRP2): specific for P.falciparum [link] b. Plasmodium lactate dehydrogenase (pLDH): different forms are specific for either P.falciparum or P.vivax [link] 2. “Pan-malaria antigens”. These detect malaria, but do not indicate the infecting species a. PpanLDH: a form of LDH present in all malaria species [link] b. Aldolase: a malaria-specific form of aldolase that is present in all species [link]