Rapid Diagnostic Tests for Malaria Diagnosis in the Peruvian Amazon: Impact of pfhrp2 Gene Deletions and Cross-Reactions

Abstract

BackgroundIn the Peruvian Amazon, Plasmodium falciparum and Plasmodium vivax malaria are endemic in rural areas, where microscopy is not available. Malaria rapid diagnostic tests (RDTs) provide quick and accurate diagnosis. However, pfhrp2 gene deletions may limit the use of histidine-rich protein-2 (PfHRP2) detecting RDTs. Further, cross-reactions of P. falciparum with P. vivax-specific test lines and vice versa may impair diagnostic specificity.MethodsThirteen RDT products were evaluated on 179 prospectively collected malaria positive samples. Species diagnosis was performed by microscopy and confirmed by PCR. Pfhrp2 gene deletions were assessed by PCR.ResultsSensitivity for P. falciparum diagnosis was lower for PfHRP2 compared to P. falciparum-specific Plasmodium lactate dehydrogenase (Pf-pLDH)- detecting RDTs (71.6% vs. 98.7%, p<0.001). Most (19/21) false negative PfHRP2 results were associated with pfhrp2 gene deletions (25.7% of 74 P. falciparum samples). Diagnostic sensitivity for P. vivax (101 samples) was excellent, except for two products. In 10/12 P. vivax-detecting RDT products, cross-reactions with the PfHRP2 or Pf-pLDH line occurred at a median frequency of 2.5% (range 0%–10.9%) of P. vivax samples assessed. In two RDT products, two and one P. falciparum samples respectively cross-reacted with the Pv-pLDH line. Two Pf-pLDH/pan-pLDH-detecting RDTs showed excellent sensitivity with few (1.0%) cross-reactions but showed faint Pf-pLDH lines in 24.7% and 38.9% of P. falciparum samples.ConclusionPfHRP2-detecting RDTs are not suitable in the Peruvian Amazon due to pfhrp2 gene deletions. Two Pf-pLDH-detecting RDTs performed excellently and are promising RDTs for this region although faint test lines are of concern.

Evaluation of the Sensitivity of a pLDH-Based and an Aldolase-Based Rapid Diagnostic Test for Diagnosis of Uncomplicated and Severe Malaria Caused by PCR-Confirmed Plasmodium knowlesi, Plasmodium falciparum, and Plasmodium vivax

“…False-negative results occurred in only two patients, both of whom had already commenced antimalarial treatment. This finding confirms another recent report of the excellent sensitivity of the First Response RDT for detecting P. vivax (34). In our study this RDT also performed well for P. falciparum; the sensitivity of the HRP2 component of the test was 98% overall and 100% among patients with severe disease.…”

“…In our study this RDT also performed well for P. falciparum; the sensitivity of the HRP2 component of the test was 98% overall and 100% among patients with severe disease. This provides confirmation from Southeast Asia of recent reports of the very high sensitivity of HRP2-based RDTs in severe falciparum malaria in Africa (21,23) and India (22), despite the potential for geographic genetic variability in PfHRP2 (34)(35)(36)(37).…”

Recombination and Diversification of the Variant Antigen Encoding Genes in the Malaria Parasite Plasmodium falciparum

“…Because of their location within subtelomeric domains, these deletions often included the loss of members of multicopy gene families. Similar deletions have also been noted in field isolates, thus the most frequently observed structural variation is related to genetic loss (51,52,53,54). The most thorough evaluation of genetic changes resulting from long-term asexual replication was performed with clones of laboratory lines grown in vitro for up to a year, then recloned and analyzed by both microarray hybridization and whole genome sequencing (55).…”

Evaluación de campo de la precisión diagnóstica de la prueba de diagnóstico rápido SD Bioline Malaria Antigen Pf/Pv® en Colombia

“…Es así que en Colombia se han evaluado en los últimos años pruebas que detectan estos antígenos, como Now ICT Malaria Pf/ Pv ®, Diamed OptiMAL-IT ® Malaria y Paracheck-Pf ®, con el fin de conocer su capacidad diagnóstica, generalmente con buenos resultados (25)(26)(27)(28) Sin embargo, es importante seguir profundizando en la investigación de otros antígenos blanco con el fin de lograr niveles más altos en la sensibilidad y especificidad de las pruebas de diagnóstico rápido, y para evitar diagnósticos con resultados falsos negativos como ocurre en el caso de las cepas de P. falciparum que no expresan la HRP II, por deleción del gen que codifica para este antígeno, situación que se ha presentado principalmente en aislamientos de parásitos de la región amazónica (14,29,30).…”