ABSTRACT

To determine the diversity and connectivity of infections in Northwestern and Southwestern Cameroon, 232 Plasmodium falciparum infections, collected in 2018 from the Ndop Health District (NHD) in the western savannah highlands in the Northwest and the Limbe Health District (LHD) in the coastal lowland forests in the Southwest of Cameroon were genotyped for nine neutral microsatellite markers. Overall infection complexity and genetic diversity was significantly (p < 0.05) lower in NHD than LHD, (Mean MOI = 2.45 vs. 2.97; Fws = 0.42 vs. 0.47; Mean He = 0.84 vs. 0.89, respectively). Multi-locus linkage disequilibrium was generally low but significantly higher in the NHD than LHD population (mean I^S_A= 0.376 vs 0.093). Consequently, highly related pairs of isolates were observed in NHD (mean IBS = 0.086) compared to those from the LHD (mean IBS = 0.059). Infections from the two regions were mostly unrelated (mean IBS = 0.059), though the overall genetic differentiation across the geographical range was low. Indices of differentiation between the populations were however significant (overall pairwise Fst = 0.048, Jost’s D = 0.133, p < 0.01). Despite the high human migration across the 270km separating the study sites, these results suggest significant restrictions to gene flow against contiguous geospatial transmission of malaria in west Cameroon. Clonal infections in the highland sites could be driven by lower levels of malaria prevalence and seasonal transmission. How these differences in genetic diversity and complexity affect responses to interventions such as drugs will require further investigations from broader community sampling.

摘要

为了确定喀麦隆西北部和西南部感染的多样性和连通性，2018 年从西北萨凡纳高地的恩多普卫生区 (NHD) 和沿海低地的林贝卫生区 (LHD) 收集了 232 例恶性疟原虫感染病例对喀麦隆西南部的森林进行了九个中性微卫星标记的基因分型。NHD 的总体感染复杂性和遗传多样性显着低于 LHD（p < 0.05）（平均 MOI = 2.45 vs. 2.97；Fws = 0.42 vs. 0.47；平均 He = 0.84 vs. 0.89）。NHD 人群的多位点连锁不平衡普遍较低，但显着高于 LHD 人群（平均 I ^S _A = 0.376 vs 0.093）。因此，与 LHD 中的分离株（平均 IBS = 0.059）相比，在 NHD 中观察到高度相关的分离株对（平均 IBS = 0.086）。尽管整个地理范围内的总体遗传分化较低，但来自两个地区的感染大多无关（平均 IBS = 0.059）。然而，群体之间的分化指数显着（总体成对 Fst = 0.048，Jost 的 D = 0.133，p < 0.01）。尽管研究地点相距 270 公里，人类大量迁徙，但这些结果表明，喀麦隆西部疟疾的连续地理空间传播基因流动受到了显着限制。高地地区的克隆感染可能是由于疟疾流行率较低和季节性传播所致。这些遗传多样性和复杂性的差异如何影响对药物等干预措施的反应将需要通过更广泛的社区抽样进行进一步调查。