Malaria drug resistance and associated diagnostic failures in arriving refugee children at Adjumani and Kyangwali reception centers in Uganda

Abstract

Malaria, caused by Plasmodium falciparum (Pf), is one of the most important infections in African children and a leading cause of morbidity and mortality among refugees in sub-Saharan Africa. Uganda is one of the largest refugee hosting countries in the world, and the largest in sub-Saharan Africa, with over 1.4 million refugees. Serious threats to malaria control in sub-Saharan Africa include recent reports that there’s resistance to artemisinins (Tukwasibwe et al., 2017); the backbones of first line combination therapies to treat malaria, and P. falciparum Histidine Rich Protein 2 (PfHRP) gene deletions mediating false negative rapid diagnostic tests for malaria (mRDTs), have emerged in East Africa (Nsobya et al., 2021). A retrospective study involving utilization of 211 Blood Slide (BS) positive stored Dried Blood Spots (DBS) samples and 10 mRDT negative samples from newly arriving children aged 6 months to 10 years was conducted at 2 refugee camps in Kyangwali (from eastern Congo) and Adjumani (from Southern Sudan) in 2022. Samples were then packaged appropriately and transported to the IDRC-National Malaria Reference Laboratory. Molecular Inversion Probe (MIPs) was then prepared, samples sequenced and analyzed for malaria drug resistance markers and HRP2/3 deletions The positivity rate for RDT was 36.5% (Adjumani) and 67.2% (Kyangwali) among the refugees. Prevalences of mutations associated with aminoquinoline resistance were much higher in Adjumani. Prevalences of mutations associated with high level sulfadoxine-pyrimethamine and dihydroartemisinin-piperaquine resistance were much higher in Kyangwali (61.0% and 48.1% for PfDHFR I164L and PfDHPS A581G, p-values <0.001 for both mutations). The prevalence of PfK13 mutations associated with artemisinin partial resistance was higher (8% and 15.4% for A675V and C469Y, p-values 0.05 and 0.030 respectively) in Adjumani compared to Kyangwali. The prevalence of mutations associated with with high level aminoquinoline resistance was much higher in Adjumani with 48.7% for PfCRT K76T p-value <0.001 and 33.3% for PfMDR1 N86Y, p-value <0.001. Discordant diagnostic results were uncommon and not explained by PfHRP2 deletions. This study required to be run on a national level to get a clear picture of transmission of resistance markers in Uganda. The PfHRP2 assay required a parasitemia of >100 p/uL to be able to get meaningful results for analysis.