Ex vivo P. falciparum from High vs Low transmission areas in east Africa

The aim of this study was to compare the transcriptomes of Plasmodium falciparum parasites sourced from high vs. low malaria transmission settings in east Africa in order to test the hypothesis that malaria parasites are locally adapted to their environment. In three separate experiments, parasites from ‘High’ vs. ‘Low’ transmission populations were taken from non-immune children and measured for gene expression levels by microarray against a reference genome. Two of these population comparisons were geographic in nature while the third was temporal, i.e., before and after a marked decline in malaria. This study is described in Rono MK, Nyonda MA, Simam JJ, Ngoi, JM et al. Nat Ecol Evol. PMID: . 515 samples were analysed. These derived from 96 parasite isolates obtained from children below 13 years of age with three or fewer previous clinical episodes of malaria who were diagnosed with uncomplicated P. falciparum malaria at hospitals and dispensaries in western Kenya (2008, Kisumu), coastal Kenya (Kilifi, in 1994-1996 and in 2010-2012) and eastern Sudan (2007) which have long-term high, medium and low malaria transmission intensities, respectively. Each isolate was placed into in vitro culture and sampled every 10h for up to 9 times: this yielded parasites at all stages of maturity during the 48h intraerythrocytic development cycle. Five of the 96 isolates were replicates but were processed separately.