High genetic diversity of Plasmodium falciparum in the low transmission setting of the Kingdom of Eswatini

Abstract

Background

The impact of indoor residual spraying on Plasmodium falciparum microsatellite variation in an area of high seasonal malaria transmission in Ghana, West Africa

“…The significant reductions in P. falciparum prevalence in Soe following the IRS intervention means that these imported infections from Burkina Faso are more likely to be represented in our sampled population. Such observations have been reported within regions of sub‐Saharan Africa (Bei et al, 2018; Duffy et al, 2017; Lynch & Roper, 2011; Mobegi et al, 2012; Roh et al, 2019; Sharp et al, 2007). Moreover, the implementation of control interventions in Burkina Faso has been limited to only 10%–40% population‐wide distribution of LLINs between 2010–2014 (Samadoulougou et al, 2017).…”

“…An alternative explanation for the lack of multilocus LD is that even if outcrossing was reduced following the IRS, continuous gene flow via migration of P. falciparum clones from the surrounding uncontrolled areas may have increased genetic diversity but not LD (see discussion below). This contrasts with the surveillance application of microsatellites to detect changes in LD when going from moderate‐ to low‐transmission as observed in low‐transmission areas, including those with perturbations such as LLINs and ACTs ( Carter et al, 2015; Chenet et al, 2012; Kattenberg et al, 2020; Roh et al, 2019). Some pursuing multiple single nucleotide polymorphisms (SNPs) or microhaplotypes for surveillance may speculate that additional loci could increase resolution to detect changes in LD.…”

“…The latter are “ideal elimination units” that may lead to a population bottleneck and where clonal parasites may be more readily lost to genetic drift events (Cotton et al, 2018; Escalante et al, 2015). Gene flow from higher transmission neighbouring regions can also increase diversity in areas of lower transmission or under malaria control (Branch et al, 2011; Roh et al, 2019). The high‐transmission genetic profile is characteristic of much of sub‐Saharan Africa that has been recently prioritized by the Roll Back Malaria Partnership and World Health Organization's (WHO) “High Burden to High Impact” (HBHI) country‐led approach to accelerate progress against malaria.…”

Using parasite genetic and human mobility data to infer local and cross-border malaria connectivity in Southern Africa

“…low risk of inbreeding). F WS was calculated as described previously (Roh et al, 2019; Auburn et al, 2012). Briefly, F WS was calculated for each infection using the formula, FWS=1-HwHs where Hw= heterozygosity of the individual and Hs= heterozygosity of the local parasite population.…”