High Prevalence of <i>Pfhrp</i>2/3 Gene Deletions and Major Threat to Malaria Control Programs in Ethiopia

Abstract

<b>Background:</b> Rapid diagnostic tests (RDTs) targeting <i>pf</i>histidine-rich protein 2 (<i>Pfhrp</i>2) are widely used for diagnosis of <i>Plasmodium falciparum</i> infections in resource-limited malaria endemic countries. However, test results are affected by deletions of the <i>Pfhrp2</i>, <i>Pfhrp3</i>, and flanking genes and associated negative results from rapid diagnostic devices were previously reported. Therefore, the aim of this study was to reveal the existing genetic profile of <i>Pfhrp</i>2 and <i>Pfhrp</i>3 genes of <i>P. falciparum</i>-infected patients in northwestern Ethiopia. <b>Methods:</b> A total number of 302 blood samples were collected from children at Chilga (Aykel, Negade Bahir), and Sanja health centers in northwestern Ethiopia. Thirty-three (10.9%) samples tested positive for <i>P. falciparum</i> malaria. The <i>Pfhrp</i>2, <i>Pfhrp</i>3, and flanking genes (MAL7P1_228 and MAL7P1_230 for <i>Pfhrp</i>2, and MAL13P1_475 and MAL13P1_485 for <i>Pfhrp</i>3) were amplified using standard nested-PCR. <b>Results:</b> <i>Pfhrp</i>2 and both of its flanking genes were found to be present in 12 (36.4%) out of the 33 samples. Twenty-one (63.6%) samples tested negative for the <i>Pfhrp2</i> gene and 19 samples (57.6%) tested positive for at least one of the flanking genes. Five (15.2%) samples gave positive results for the <i>Pfhrp</i>3 gene and both of its flanking genes, whereas 16 (48.5%) tested negative for all three. <b>Conclusions:</b> Our study provides widespread deletions in the <i>Pfhrp</i>2 and <i>Pfhrp</i>3 genes in Ethiopia, thereby confirming anecdotal reports of diagnostic failure with <i>Pfhrp</i>2-based RDTs in the region. The implications of our finding for the current diagnostic paradigm, which relies on the detection of <i>P. falciparum</i> by <i>Pfhrp</i>2-based RDTs in remote areas, may need rethinking.