Evaluation of the rapid diagnostic test SDFK40 (Pf-pLDH/pan-pLDH) for the diagnosis of malaria in a non-endemic setting

Abstract

BackgroundThe present study evaluated the SD Bioline Malaria Ag 05FK40 (SDFK40), a three-band RDT detecting Plasmodium falciparum-specific parasite lactate dehydrogenase (Pf-pLDH) and pan Plasmodium-specific pLDH (pan-pLDH), in a reference setting.MethodsThe SDFK40 was retrospectively and prospectively tested against a panel of stored (n = 341) and fresh (n = 181) whole blood samples obtained in international travelers suspected of malaria, representing the four Plasmodium species as well as Plasmodium negative samples, and compared to microscopy and PCR results. The prospective panel was run together with OptiMAL (Pf-pLDH/pan-pLDH) and SDFK60 (histidine-rich protein-2 (HRP-2)/pan-pLDH).ResultsOverall sensitivities for P. falciparum tested retrospectively and prospectively were 67.9% and 78.8%, reaching 100% and 94.6% at parasite densities >1,000/μl. Sensitivity at parasite densities ≤ 100/μl was 9.1%. Overall sensitivities for Plasmodium vivax and Plasmodium ovale were 86.7% and 80.0% (retrospectively) and 92.9% and 76.9% (prospectively), reaching 94.7% for both species (retrospective panel) at parasite densities >500/μl. Sensitivity for Plasmodium malariae was 21.4%. Species mismatch occurred in 0.7% of samples (3/411) and was limited to non-falciparum species erroneously identified as P. falciparum. None of the Plasmodium negative samples in the retrospective panel reacted positive. Compared to OptiMAL and SDFK60, SDFK40 showed lower sensitivities for P. falciparum, but better detection of P. ovale. Inter-observer agreement and test reproducibility were excellent, but lot-to-lot variability was observed for pan-pLDH results in case of P. falciparum.ConclusionSDFK40 performance was poor at low (≤ 100/μl) parasite densities, precluding its use as the only diagnostic tool for malaria diagnosis. SDFK40 performed excellent for P. falciparum samples at high (>1,000/μl) parasite densities as well as for detection of P. vivax and P. ovale at parasite densities >500/μl.

Comparison of Two Rapid Diagnostic Tests with Conventional Microscopy for Detection of Malaria parasites

“…Another study that was performed at Combined Military Hospital Quetta by Ahmad et al (2003), concluded 100% OptiMAL sensitivity for both malaria species. Another study was performed in Belgium( non-endemic country for malaria ), reported sensitivity of 92.9% for the SD Bioline Malaria Ag Pf/Pan (Maltha et al, 2011) while in Korea, the researchers reported a sensitivity of RDT for P. vivax that ranged from 86.8% to 92.7% (Kim et al, 2011 ;Jang et al, 2013). The results of the present study are more or less similar in sensitivity to most of the above mentioned studies performed worldwide for malaria diagnosis.…”

Use of a pLDH-based dipstick in the diagnostic and therapeutic follow-up of malaria patients in Mali

“…All P. falciparum malaria cases with parasitemia greater than 1000 trophozoites/μl of blood were detected as previously described [20]. However, almost 16% of blood stage asexual forms with parasitemia less than 1000/μl were not detected.…”

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

“…Lot-to-lot variation in RDTs is a well-known issue in performance, monitoring and quality control of RDTs [13,16]. As slight – but important – differences between lots such as those presently observed will probably go undetected by routine lot control procedures, efforts should be made at the level of manufacturing and post-marketing surveillance to assure equal performance of different RDT lots.…”