A Review of Malaria Diagnostic Tools: Microscopy and Rapid Diagnostic Test (RDT)

Abstract

The absolute necessity for rational therapy in the face of rampant drug resistance places increasing importance on the accuracy of malaria diagnosis. Giemsa microscopy and rapid diagnostic tests (RDTs) represent the two diagnostics most likely to have the largest impact on malaria control today. These two methods, each with characteristic strengths and limitations, together represent the best hope for accurate diagnosis as a key component of successful malaria control. This review addresses the quality issues with current malaria diagnostics and presents data from recent rapid diagnostic test trials. Reduction of malaria morbidity and drug resistance intensity plus the associated economic loss of these two factors require urgent scaling up of the quality of parasite-based diagnostic methods. An investment in anti-malarial drug development or malaria vaccine development should be accompanied by a parallel commitment to improve diagnostic tools and their availability to people living in malarious areas.

Evaluation of a rapid diagnostic test (CareStart™ Malaria HRP-2/pLDH (Pf/pan) Combo Test) for the diagnosis of malaria in a reference setting

“…Reported sensitivities for the detection of P. vivax were significantly higher than those found in the present study in case of the CareStart™ Malaria pLDH (pan) (91.0%), but for the CareStart™ Malaria pLDH (pan/Pf) they were in line with the present findings (78.5%). Studies evaluating other RDTs in non-endemic countries report similar sensitivities as those found for the CareStart™ Malaria HRP-2/pLDH (Pf/pan) Combo Test in the present study: for P. falciparum they ranged from 87.5-99.0%, with one exception of 76.2% [7,10,16-21]. For P. vivax , RDTs detecting pan-pLDH showed sensitivities of 33.5% and 62.0%-95.0%,[7,10,13,18,20,22] compared to 46.0%-93.0% [13] for those RDTs targeting aldolase.…”

The silent threat: asymptomatic parasitemia and malaria transmission

“…The detection limits of microscopy are typically estimated at 4-20 p/µl in a reference laboratory, but are more realistically 50-100 p/µl under field conditions [43]. A few rapid diagnostic tests (RDTs) have been shown to have greater than 90% sensitivity and specificity for P. falciparum at parasite densities ≥200 p/µl [43][44][45] but may often fail to detect lower density infections. PCR is considered to be the gold standard for detection of parasitemia with a limit of detection of 0.02 p/µl for the most sensitive procedures [46].…”

The effectiveness of microscopy: Rapid diagnostic test and molecular assay in diagnosing malaria.

“…This method has been in use for century and has been the main tool for diagnosis of malaria in laboratories [7]. This method is relatively simple and requires less training of the microscopists; with an average sensitivity of about 50-100 parasites per microliter of blood [8,9]. Also, this method detects different species of Plasmodium in specimens.…”