Effects of transmission reduction by insecticide-treated bed nets (ITNs) on parasite genetics population structure: I. The genetic diversity of Plasmodium falciparum parasites by microsatellite markers in western Kenya.

Gatei, Wangeci, Kariuki, Simon, Hawley, William, terKuile, Feiko ORCID: https://orcid.org/0000-0003-3663-5617, Terlouw, Anja ORCID: https://orcid.org/0000-0001-5327-8995, Phillips-Howard, Penelope, Nahlen, Bernard, Gimnig, John, Lindblade, Kim, Walker, Edward, Hamel, Mary, Crawford, Sara, Williamson, John, Slutsker, Laurence and Shi, Ya Ping (2010) 'Effects of transmission reduction by insecticide-treated bed nets (ITNs) on parasite genetics population structure: I. The genetic diversity of Plasmodium falciparum parasites by microsatellite markers in western Kenya.'. Malaria Journal, Vol 9, Issue 353.

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Abstract

Background: Insecticide-treated bed nets (ITNs) reduce malaria transmission and are an important prevention tool.
However, there are still information gaps on how the reduction in malaria transmission by ITNs affects parasite
genetics population structure. This study examined the relationship between transmission reduction from ITN use
and the population genetic diversity of Plasmodium falciparum in an area of high ITN coverage in western Kenya.
Methods: Parasite genetic diversity was assessed by scoring eight single copy neutral multilocus microsatellite (MS)
markers in samples collected from P. falciparum-infected children (< five years) before introduction of ITNs (1996,
baseline, n = 69) and five years after intervention (2001, follow-up, n = 74).
Results: There were no significant changes in overall high mixed infections and unbiased expected heterozygosity
between baseline (%MA = 94% and He = 0.75) and follow up (%MA = 95% and He = 0.79) years. However, locus
specific analysis detected significant differences for some individual loci between the two time points. Pfg377 loci,
a gametocyte-specific MS marker showed significant increase in mixed infections and He in the follow up survey
(%MA = 53% and He = 0.57) compared to the baseline (%MA = 30% and He = 0.29). An opposite trend was
observed in the erythrocyte binding protein (EBP) MS marker. There was moderate genetic differentiation at the
Pfg377 and TAA60 loci (FST = 0.117 and 0.137 respectively) between the baseline and post-ITN parasite populations.
Further analysis revealed linkage disequilibrium (LD) of the microsatellites in the baseline (14 significant pair-wise
tests and IS
A = 0.016) that was broken in the follow up parasite population (6 significant pairs and IS
A = 0.0003).
The locus specific change in He, the moderate population differentiation and break in LD between the baseline
and follow up years suggest an underlying change in population sub-structure despite the stability in the overall
genetic diversity and multiple infection levels.
Conclusions: The results from this study suggest that although P. falciparum population maintained an overall
stability in genetic diversity after five years of high ITN coverage, there was significant locus specific change
associated with gametocytes, marking these for further investigation.

Item Type:	Article
Subjects:	QX Parasitology > Protozoa > QX 135 Plasmodia QX Parasitology > Insects. Other Parasites > QX 600 Insect control. Tick control WC Communicable Diseases > Tropical and Parasitic Diseases > WC 765 Prevention and control
Digital Object Identifer (DOI):	https://doi.org/10.1186/1475-2875-9-353
Depositing User:	Helen Wong
Date Deposited:	05 Jan 2011 12:01
Last Modified:	13 Sep 2019 13:10
URI:	https://archive.lstmed.ac.uk/id/eprint/1713

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