How effective are rapid diagnostic tests (RDT) in the workup of malaria?

Updated: Apr 26, 2019
  • Author: Thomas E Herchline, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Immunochromatographic tests based on antibody to histidine-rich protein-2 (PfHRP2), parasite LDH (pLDH), or Plasmodium aldolase appear to be very sensitive and specific. [11, 12] Some RDTs may be able to detect P falciparum in parasitemias that are below the threshold of reliable microscopic species identification. Only one RDT (BinaxNOW) has been approved to date for the diagnosis of malaria in the United State. [13]

In one study, RDTs were found to perform better than microscopy under routine conditions. RDTs performed by the health facility staff were 91.7% sensitive and 96.7% specific. Microscopy was 52.5% sensitive and 77% specific. [14] A recent sudy using loop-mediated amplification technique (LAMP)also suggests that RDTs have accuracy similar to that of nested PCR, with a greatly reduced time to result, and was superior to expert microscopy. [15]

In a study from Tanzania, d'Acremont et al reported that antimalarials could be safely withheld from febrile children (< 5 y) who had negative results from an RDT based on PfHRP2. [16]

RDTs are less effective when parasite levels are below 100 parasites/mL of blood, and, in rare instances, an RDT test is negative in patients with high parasitemias. For these reasons, confirm RDT test results with a second type of screening test when possible. A false-positive result from an RDT may occur up to 2 weeks or more after treatment due to persistence of circulating antigens.


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