RDT Quiz A Q1

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RDT Quiz A 1. For which TWO malarial species do appropriate RDT tests have best sensitivity (make two selections)? P.falciparum P.vivax P.ovale P.malariae P.knowlesi Explanation of correct answer (click "Expand") The different malaria species are detected with different sensitivity. The table below provides an overall summary of the sensitivity that can be expected for RDT tests when suitable species-specific together with pan-malarial antibodies are used. The table is only a broad summary. P.falciparum1 At high parasitaemia expect high sensitivity (90-95%). This declines when parasite levels are lower (45-70%)2 P.vivax Expect moderate to high sensitivity at high parasitaemia (70-90%). This declines markedly when parasite levels are lower (30-60%)2 P.ovale & P.malarae Generally sensitivity is poor (approximately half the sensitivity shown for P.vivax) P.knowlesi3 Reports suggest variable sensitivity that may depend on test used, RDTs are reported tp detect this species well when parasitaemia is high. Notes: 1 HRP2 mutation mean that in some geographical areas the diagnostic sensitivity may be significantly lower for HRP2-based tests (see below) 2 Low parasite number is considered as (<1000 parasites/μL) a level that may cause symptoms in children or non-immune travellers 3 There have been relatively few studies with this species so caution is required in RDT interpretation Go to next question (2 of 5)