Associations between plasmodium falciparum aminoquinoline resistance genotypes and clinical presentations of malaria in Ugandan children, A case control study of Jinja District and the neighbouring Busoga Sub-Region Districts

Abstract

Plasmodium falciparum resistance mutations to aminoquinoline antimalarials are selected by prior drug use and may alter parasite fitness yet their associations with clinical malaria presentations are uncertain. Retrospectively, genotypes in samples were assessed from a case control study of determinants of severe malaria in Ugandan children aged 4 months to 10 years. 274 severe malaria cases matched by age and geographical location to 275 uncomplicated malaria and 179 asymptomatic aparasitemic controls. Target age groupings were 4 to 12 months, 1 to 3 years, 3 to 5 years, and 5 to 10 years. Adult caregivers of children with only severe or uncomplicated malaria detailed all medicines received during the acute illness. Genomic DNA was extracted from dried blood spots by using Chelex method. The PfCRT and PfMDR-1 alleles of interest were determined using a ligase detection reaction-fluorescent microsphere assay, with minor modifications, including nested PCR amplification of templates. Data was analyzed with STATA (version 14). Descriptive statistics were reported as proportions and medians with interquartile ranges. Chi-square test and the Wilcoxon signed rank test were used for categorical and continuous data, respectively. Associations between the polymorphisms and malaria outcomes were assessed by cross-tabulations with chi-square tests. Prevalence of mutations of interest was 67.2% (431) for PfCRT K76T, 8.4% (58) for PfMDR-1 N86Y, 71.4% (513) for PfMDR-1 Y184F, and 14.6% (96) for PfMDR-1 D1246Y. Compared to asymptomatic controls, the odds of mutant PfCRT 76T were lower for uncomplicated (odds ratio 0.42 (95% CI 0.24-0.72); p<0.001) or severe (0.56 (0.32-0.97); p=0.031) malaria; the odds of mutant PfMDR-1 86Y were lower for uncomplicated (0.33 (0.16-0.65); p<0.001) or severe (0.21 (0.09-0.45); p<0.001) malaria; and the odds of mutant PfMDR-1 1246Y were higher for uncomplicated (1.83 (0.90-3.98); p=0.076) or severe (2.06 (1.01-4.55); p=0.033) malaria. The odds of mutant PfMDR-1 184F were lower in severe compared to asymptomatic (0.59 (0.37-0.92); p=0.016) or uncomplicated (0.61 (0.41-0.90); p=0.009) malaria. Overall, the PfCRT 76T and PfMDR-1 86Y mutations were associated with decreased risk of symptomatic malaria, PfMDR-1 1246Y was associated with increased risk of symptomatic malaria, and PfMDR-1 184F with decreased risk of severe malaria. These results offer insights into parasite genotypes in children with different malaria clinical presentations.