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

ABSTRACT: BACKGROUND: Malaria Rapid Diagnostic Tests (RDTs) are widely used for diagnosing malaria. The present retrospective study evaluated the CareStartTM Malaria HRP-2/pLDH (Pf/pan) Combo Test targeting the Plasmodium falciparum specific antigen histidine-rich protein (HRP-2) and the pan-Plasmodium antigen lactate dehydrogenase (pLDH) in a reference setting. METHODS: The CareStartTM Malaria HRP-2/pLDH (Pf/pan) Combo Test was evaluated on a collection of samples obtained in returned international travellers using microscopy corrected by PCR as the reference method. Included were P. falciparum (n=320), Plasmodium vivax (n=76), Plasmodium ovale (n=76), Plasmodium malariae (n=23) and Plasmodium negative samples (n=95). RESULTS: Overall sensitivity for the detection of P. falciparum was 88.8%, increasing to 94.3% and 99.3% at parasite densities above 100 and 1,000/ul respectively. For P. vivax, P. ovale and P. malariae, overall sensitivities were 77.6%, 18.4% and 30.4% respectively. For P. vivax sensitivity reached 90.2% for parasite densities above 500/ul. Incorrect species identification occurred in 11/495 samples (2.2%), including 8/320 (2.5%) P. falciparum samples which generated only the pan-pLDH line. For P. falciparum samples, 205/284 (72.2%) HRP-2 test lines had strong or medium line intensities, while for all species the pan-pLDH lines were less intense, especially in the case of P. ovale. Agreement between observers was excellent (kappa values > 0.81 for positive and negative readings) and test results were reproducible. The test was easy to perform with good clearing of the background. CONCLUSION: The CareStartTM Malaria HRP-2/pLDH (Pf/pan) Combo Test performed well for the detection of P. falciparum and P. vivax, but sensitivities for P. ovale and P. malariae were poor