The Search for Plasmodium falciparum histidine–rich protein 2/3 Deletions in Zambia and Implications for Plasmodium falciparum histidine-rich protein 2-Based Rapid Diagnostic Tests

We attempted to identify Plasmodium falciparum histidine-rich protein 2/3 ( pfhrp2/3 ) deletions among rapid diagnostic test (RDT)-negative but PCR- or microscopy-positive P. falciparum -infected individuals in areas of low transmission (Choma District, 2009-2011) and high transmission (Nchelenge District, 2015-2017) in Zambia. Through community-based surveys, 5,167 participants were screened at 1,147 households by P. falciparum histidine-rich protein 2 (PfHRP2)-based RDTs. Slides were made and dried blood spots were obtained for molecular analysis. Of 28 samples with detectable P. falciparum DNA, none from Nchelenge District were pfhrp2/3 negative. All eight samples from Choma District had detectable pfhrp3 genes, but pfhrp2 was undetectable in three. DNA concentrations of pfhrp2 -negative samples were low (< 0.001 ng/μL). These findings suggest that PfHRP2-based RDTs remain effective tools for malaria diagnosis in Nchelenge District, but further study is warranted to understand the potential for pfhrp2/3 deletions in southern Zambia where malaria transmission declined over the past decade.