432 Parasitology and parasitic infections / International Journal of Infectious Diseases 101(S1) (2021) 419–436 1048 Effect of P. falciparum Kelch 13 and Pfmdr1 gene polymorphisms on parasite clearance characteristics following Artemether-Lumefantrine therapy E. Aninagyei 1,* , C.D. Tetteh 2 , A. Egyir-Yawson 3 , D. Omane Acheampong 3 1 University of Cape Coast, Department of Biomedical Sciences, Cape Coast, CR, Ghana 2 Municipal Health Directorate, Ga West Municipal, Amasaman-Ghana, Ghana Health Service, Accra, Ghana 3 University of Cape Coast, Department of Biomedical Sciences, Cape Coast, Ghana Background: Several polymorphisms in Plasmodium falcipa- rum Kelch 13 and Pfmdr1 genes have been identified. This study reports the effects of identified Kelch 13 and Pfmdr1 genes polymorphisms on parasite clearance characteristics following Artemether-Lumefantrine therapy in Ghana. Methods & Materials: This study was done in Ga West Munic- ipality in Greater Accra Region, Ghana where 178 consented uncomplicated malaria patients were recruited. Each patient completed oral Artemether-Lumefantrine (LONART: Artemether 20 mg + Lumefantrine 120 mg) over a 3-day period based on the number of tablets per dose according to pre-defined weight bands (15–24 kg = 2tablets, 25–34 kg = 3tablets and >34 kg = 4 tablets). Baseline parasitaemia was determined before treatment. Six- hourly parasitaemia post-treatment was determined till clearance of parasites. Kelch 13 and Pfmdr1 were genotyped using selec- tive whole genome amplification (sWGA) while parasite clearance characteristics were determined using Parasite Clearance Estimator tool. Results: In Kelch 13 gene, four non-synonymous (A676S, C580Y, I543V and S466A) mutations were identified in 55 (30.9%) isolates. Three different mutant alleles (N86Y, Y184F and N1246Y) in Pfmdr1 gene were identified in 88 (49.4%) isolates. Two geo-political novel Kelch 13 SNPs were identified in 21 (11.7%) isolates; I543V (n = 17) and S466A (n = 13). Eight isolates had dual I543V and S466A muta- tions and 39 isolates had one or more mutations in both Kelch 13 and Pfmdr1. I543V but not S466A was associated with significantly low mean clearance rate constant (I543V = 0.096 vs. S466A = 0.174), high mean slope half-life (I543V = 7.23 h vs. S466A = 3.99 h) and prolonged mean parasite clearance times (PCTs) (I543V = 50.42 h vs. S466A = 29.02 h). However, S466A co-mutation with I543 V was associated with markedly prolonged PCT (mean PCT99 = 95.36 h) and very mean high slope half-life of 12.8 h. Conclusion: This study provides evidence of Kelch 13 and Pfmdr1 mutations (putative artemisinin resistance) in Ghana. I453V and S466N were newly identified Kelch 13 mutations in Ghanaian. I543V and S466N/I543V synergism were found to cause delayed parasite clearance in response to Artemether-Lumefantrine therapy. https://doi.org/10.1016/j.ijid.2020.09.1132 1049 Characterization of putative drug resistant markers in Plasmodium falciparum isolated in Ghanaian blood donors E. Aninagyei * , D. Omane Acheampong, P. Ampomah, A. Egyir-Yawson, A. Boye University of Cape Coast, Department of Biomedical Sciences, Cape Coast, CR, Ghana Background: Plasmodium falciparum parasites are commonly detected in blood donors in malaria-endemic areas. Even though few cases of transfusion-transmitted malaria have been reported, this study sought to establish the relative proportions of putative anti-malaria drug biomarkers in Ghanaian blood donors. Methods & Materials: Blood donors were randomly selected from five districts in Greater Accra region, Ghana. Each donor sam- ple was screened with SD Bioline rapid diagnostic test kit (RDT). Dry blood spots were prepared from positive samples and shipped to Malaria Genome Laboratory, Wellcome Sanger Institute, Hinxton- UK for sequencing by genotyping of Pfcrt, Pfmdr1, Pfdhfr, Pfdhps and Kelch 13 genes. Results: A total of 771 blood donors were sampled out of which 91 (11.8%) were confirmed infected by RDT. Analysis of sequence reads indicated successful genotyping of Pfcrt, Pfmdr1, Pfdhfr, Pfdhps and Kelch 13 genes in 67 (73.6%), 64 (70.3%), 69 (75.8%), 69 (75.8%) and 84 (92.3%) of the genotyped isolates respectively. Of the total isolates, 191 different mutant haplotypes and single nucleotide polymorphisms were identified. In Pfcrt, CVIET haplotype was observed in 9 (13.4%) samples. In Pfmdr1, NFD, NYY, YFN and NFY haplotypes were identified in 4 (6.3%), 4 (6.3%), 6 (9.4%) and 8 (12.5%) samples respectively. In Pfdhfr gene single [NRSI, n = 17 (24.6%); NCNI, n = 20 (28.9%)], double [IRNI, n = 13 (18.8%); NRNI, n = 6 (8.6%)] and triple [IRNI, n = 6 (8.6%)] mutations were observed while in Pfdhps gene, the following haplotypes were seen: SGKAA (n = 19, 27.5%), AGKAA (n = 17, 24.6%), AGKAS (n = 13, 18.8%), AGKSA (n = 9, 13.0%), FGKAS (n = 5, 7.2%), AGKSS (n = 5, 7.2%) and AGESS (n = 1, 1.4%). Finally, in Kelch 13 gene, four non-synonymous muta- tions were identified in 11 isolates; P615L (n = 4, 4.8%), A578S (n = 4, 4.8%), I543 V (n = 2, 2.4%) and A676S (n = 1, 1.2%). Conclusion: The results obtained in this study indicated up to 28.9% risk of being transmitted with anti-malaria drug resistant gene during transfusion of P. falciparum infected blood. However, not higher than 12.5% putative drug resistant biomarkers could reduce efficacy of artemisinin combination therapy. https://doi.org/10.1016/j.ijid.2020.09.1133 1050 Onchocerciasis-associated epilepsy an unrecognised important preventable public health problem R. Colebunders 1,* , J.N. Siewe Fodjo 1 , A. Dusabimana 1 , M. Mandro 2 , D. Bhwana 3 , N. Gumisiriza 4 , A. Hotterbeekx 1 1 University of Antwerp, Global Health Institute, Antwerp, Belgium 2 Ministry of Health, Bunia, Congo 3 NIMR, Tanga, Tanzania 4 Busitema University, Mbale, Uganda Background: 5 years ago we started the NSETHIO project to investigate whether nodding syndrome (NS) could be caused by onchocerciasis.