No Evidence of Piperaquine Resistance in Southeast Nigeria

Artemisinin-based combination therapies (ACTs) are currently the first-line treatment for uncomplicated malaria. However, ACTs are being threatened by the emergence of Plasmodium falciparum strains resistant to artemisinins as well as their partner drugs. Periodical surveillance of drug efficacy and molecular markers associated with resistance is required to monitor this. Resistance to piperaquine (PPQ), the partner drug in the ACT dihydroartemisinin-piperaquine, is spreading in Asia, and mutations associated with PPQ resistance have been reported in some African countries. In Nigeria, this has never been reported. This study aimed to assess markers of PPQ resistance—specifically, the T93S, H97Y, and F145I SNPs in exons 2 and 3 of the P. falciparum chloroquine resistance transporter (pfcrt) gene—and to examine amplification of the plasmepsin 2 and 3 genes (pfpm2/3) in 268 patient samples collected from Nnewi, Southeastern Nigeria, in 2019. SNPs were identified using PCR followed by sequencing, while pfpm2/3 copy number was determined by qPCR. No pfcrt SNPs of interest were detected, and no increase in copy number for pfpm2 or pfpm3 was observed in any sample. The absence of these PPQ resistance markers suggests that PPQ remains an effective partner drug in ACTs in this region. However, continuous monitoring of circulating P. falciparum parasites in Nigeria is crucial to promptly detect and respond to potential resistance development.