Circulation of Non- falciparum Species in Niger: Implications for Malaria Diagnosis

Background: Niger's National Malaria Control Programme and its partners use histidine-rich protein 2-based RDTs, which are specific to Plasmodium falciparum diagnosis. This study aimed to screen for the circulation of non-falciparum species in Zinder, a region of Niger, West Africa.

Methods: A cross-sectional study was carried out from July to December 2022 at the district hospital of the Zinder region of Niger. P falciparum histidine-rich protein 2-based rapid diagnostic tests were performed, and dried blood spot samples were collected for further laboratory multiplexed photo-induced electron transfer-polymerase chain reaction (PET-PCR) analysis on positive light microscopy from all patients with fever who attended the Zinder district hospital during the study period.

Results: In total, 340 dried blood spots were collected and analyzed by PET-PCR. Overall, 73.2% (95% CI, 68.2%-77.9%; 249/340) were positive for Plasmodium genus and species and represented the study population. Plasmodium species proportions were 89.5% (95% CI, 85.1%-93.1%; 223/249) for P falciparum, 38.5% (95% CI, 32.5%-44.9%; 96/249) for P malariae, 10.8% (95% CI, 7.3%-15.4%; 27/249) for P vivax, and 1.6% (95% CI, .4%-4.1%; 4/249) for P ovale. Single infection with Plasmodium species counted for 61.8% (95% CI, 55.5%-67.9%; 154/249), and the mixed infections rate, with at least 2 Plasmodium species, was 38.1% (95% CI, 32.1%-44.5%; 95/249). Single non-falciparum infections represented a rate of 10.0% (95% CI, 6.6%-14.5%; 25/249).

Conclusion: This study confirms the first evidence of Plasmodium vivax by PET-PCR in Niger in addition to the other 3 Plasmodium species. These findings underline the need to adapt malaria diagnostic tools and therapeutic management, as well as the training of microscopists, for recognition of non-falciparum plasmodial species circulating in the country. This will better inform the strategies toward malaria control and elimination, as well as the decision making of the health authorities of Niger.