Genetic diversity and population structure of Schistosoma mansoni within human infrapopulations in Mwea, central Kenya assessed by microsatellite markers

Abstract

A recently developed high-throughput technique that allows multi-locus microsatellite analysis of individual miracidia of Schistosoma mansoni was used to assess the levels of genetic diversity and population structure in 12 infrapopulations of the parasite, each infrapopulation derived from an infected school child from the Mwea area, central Kenya. The mean number of alleles per locus was in the range 8.22 -10.22, expected heterozygosity in Hardy-Weinberg equilibrium was 0.68 -0.70, and pair wise F ST values ranged from 0.16 −3.98% for the 12 infrapopulations. Although the genetic diversity within each infrapopulation of S. mansoni in this area was generally high, low levels of genetic structure were observed, suggestive of high levels of gene flow among infrapopulations. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Private alleles were found in 8 of the 12 infrapopulation, the highest number of private alleles recorded per infrapopulation was 3. Our data suggest that the level of gene flow among infrapopulations of S. mansoni in Mwea is extremely high thus, providing opportunity for spread of rare alleles, including those that may confer character traits such as drug resistance and virulence. NIH Public AccessAuthor Manuscript Acta Trop. Author manuscript; available in PMC 2010 September 1.

Testing local-scale panmixia provides insights into the cryptic ecology, evolution, and epidemiology of metazoan animal parasites

“…For example, Agola et al (2009) detected significant F ST for S. mansoni among 12 children in a localized area of Kenya. Thus, to infer transmission among definitive hosts, adult parasites should be sampled.…”

Applying evolutionary genetics to schistosome epidemiology

“…among individual hosts within a host population). In a rice farming irrigation region called Mwea, in the Kirinyaga District of central Kenya, samples of miracidia from school children showed significant, but low levels of pairwise subdivision among the infrapopulations of each child and among four schools that were 2 to 7 km apart (Agola et al, 2009). Thus, it appears that the geographic scale of differentiation identified can vary widely among different studies on S. mansoni .…”

Within-host competition and diversification of macro-parasites

“…within a parasite 'infrapopulation', lead to parasite diversification inside a population of conspecifics and sympatric host individuals. Several lines of evidence point at the potential significance of such adaptive speciation in macro-parasites: within-host intraspecific competition has an impact on parasite life history [19], infra-populations are often genetically diverse [20], several congeneric species can live on the same host individual [21] and within-host competition influences the patterns of associations between such species [10]. Hypothetically, within-host competition could also contribute to micro-parasite diversity because infra-populations also are genetically diverse [7,22], and competition between strains is an important force driving parasite life-history evolution [23].…”