Assessing the histidine-rich protein 2/3 gene deletion in Plasmodium falciparum isolates from Burkina Faso

Abstract

Introduction. Dual hrp2/hrp3 genes deletions in P. falciparum isolates are increasingly reported in malaria-endemic countries and can produce false negative RDT results leading to inadequate case management. Data on the frequency of hrp2/hrp3 deleted parasites are rarely available and it has become necessary to investigate the issue in Burkina Faso Methods. Plasmodium falciparum-positive dried blood spots were collected during the peak of transmission from Orodara, Gaoua, and Banfora. Amplicons from the target regions (exon 2 of hrp2 and hrp3 genes) were generated using multiplexed nested PCR and sequenced according to Illumina’s MiSeq protocol Results. A total of 251 parasite isolates were sequenced to detect hrp2 and hrp3 gene deletion. The proportion of negative cases detected by RDTs was 12.7% (32/251). The highest prevalence of negative RDTs was found in Gaoua (9.6%), followed by Orodara (2.0%), and Banfora (1.2%). Our study found that 95.6% of the parasite isolates were wild type hrp2/ hrp3 while 4.4 % (11/251) had a single hrp2 deletion. Of the 11 hrp2deletion samples, 2 samples were RDT negatives (mean parasitaemia was 83 parasites/ μL) while 9 samples were RDT positive with a median parasitaemia of 520 parasites /μL (CI95%: 192-1239). The highest frequency hrp2 deletion 4/35 (11.4%) was found in Orodara, while it was similar in the other two sites (< 3.5%). No single deletion of the hrp3 or dual deletion hrp2/3 gene was detected through this study. Conclusion. Results demonstrate that P. falciparum isolates lacking hrp2 genes are present in 4.4% of samples. They are circulating and causing malaria, but they are also still detectable by HRP2-based RTDs due to the presence of the intact pfhrp3 gene.