Applying evolutionary genetics to schistosome epidemiology

Steinauer, Michelle L.; Blouin, Michael S.; Criscione, Charles D.

doi:10.1016/j.meegid.2010.02.007

Cited by 48 publications

(45 citation statements)

References 140 publications

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“…The authors argued that the complex geography of Melquiades probably restricted host movement for water usage, resulting in focal points of transmission and thus high genetic differentiation. These data suggest that the gene flow of S. mansoni may be determined by human host mobility and that gene flow may occur across large geographical distances in the absence of boundaries between transmission sites (Steinauer et al, 2010). Similar conclusions were drawn from studies in Kenya (Agola et al, 2009) and for non-human foci (Rattus rattus) of S. mansoni (Sire et al, 2001;Prugnolle et al, 2005a).…”

Section: Introductionsupporting

confidence: 74%

Inbreeding within human Schistosoma mansoni: do host-specific factors shape the genetic composition of parasite populations?

et al. 2014

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The size, structure and distribution of host populations are key determinants of the genetic composition of parasite populations. Despite the evolutionary and epidemiological merits, there has been little consideration of how host heterogeneities affect the evolutionary trajectories of parasite populations. We assessed the genetic composition of natural populations of the parasite Schistosoma mansoni in northern Senegal. A total of 1346 parasites were collected from 14 snail and 57 human hosts within three villages and individually genotyped using nine microsatellite markers. Human host demographic parameters (age, gender and village of residence) and co-infection with Schistosoma haematobium were documented, and S. mansoni infection intensities were quantified. F-statistics and clustering analyses revealed a random distribution (panmixia) of parasite genetic variation among villages and hosts, confirming the concept of human hosts as 'genetic mixing bowls' for schistosomes. Host gender and village of residence did not show any association with parasite genetics. Host age, however, was significantly correlated with parasite inbreeding and heterozygosity, with children being more infected by related parasites than adults. The patterns may be explained by (1) genotype-dependent 'concomitant immunity' that leads to selective recruitment of genetically unrelated worms with host age, and/or (2) the 'genetic mixing bowl' hypothesis, where older hosts have been exposed to a wider variety of parasite strains than children. The present study suggests that host-specific factors may shape the genetic composition of schistosome populations, revealing important insights into host-parasite interactions within a natural system.

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Section: Introductionsupporting

confidence: 74%

Inbreeding within human Schistosoma mansoni: do host-specific factors shape the genetic composition of parasite populations?

et al. 2014

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“…Population genetics have proved to be a valuable tool in deciphering the evolutionary history of parasites as well as improving knowledge of infectious disease epidemiology (Steinauer et al, 2010; Volkman et al, 2012a). Genetic analysis can provide a glimpse into the epidemic history of a parasite that can complement epidemiological analysis or even in some cases replacing missing surveillance data (Dearlove and Wilson, 2013; Didelot et al, 2014).…”

Section: Molecular Epidemiology and Population Geneticsmentioning

confidence: 99%

Molecular epidemiology, phylogeny and evolution of the filarial nematode Wuchereria bancrofti

Small

Tisch

Zimmerman

2014

Infection, Genetics and Evolution

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Wuchereria bancrofti (Wb) is the most widely distributed of the three nematodes known to cause lymphatic filariasis (LF), the other two being Brugia malayi and B. timori. Current tools available to monitor LF are limited to diagnostic tests targeting DNA repeats, filarial antigens, and anti-filarial antibodies. While these tools are useful for detection and surveillance, elimination programs have yet to take full advantage of molecular typing for inferring infection history, strain fingerprinting, and evolution. To date, molecular typing approaches have included whole mitochondrial genomes, genotyping, targeted sequencing, and random amplified polymorphic DNA (RAPDs). These studies have revealed much about Wb biology. For example, in one study in Papua New Guinea researchers identified 5 major strains that were widespread and many minor strains some of which exhibit geographic stratification. Genome data, while rare, has been utilized to reconstruct evolutionary relationships among taxa of the Onchocercidae (the clade of filarial nematodes) and identify gene synteny. Their phylogeny reveals that speciation from the common ancestor of both B. malayi and Wb occurred around 5–6 millions years ago with shared ancestry to other filarial nematodes as recent as 15 million years ago. These discoveries hold promise for gene discovery and identifying drug targets in species that are more amenable to in vivo experiments. Continued technological developments in whole genome sequencing and data analysis will likely replace many other forms of molecular typing, multiplying the amount of data available on population structure, genetic diversity, and phylogenetics. Once widely available, the addition of population genetic data from genomic studies should hasten the elimination of LF parasites like Wb.

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“…On the other hand, the merger of subpopulations of parasite into one infrapopulation results in gene flow that will homogenize the genetic variation between infrapopulations (the parasites of a specific species in one host (Margolis et al, 1982) Archie et al, 2008;Steinauer et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

High within-host genetic variation of the nematode Spirocerca lupi in a high-density urban dog population

Waal

Gous

Clift

et al. 2012

Veterinary Parasitology

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The nematode worm Spirocerca lupi has a cosmopolitan distribution and can cause the death of its final canid host, typically dogs. While its life cycle, which involves a coprophagous beetle intermediate host, a number of non-obligatory vertebrate paratenic hosts and a canid final host, is well understood, surprisingly little is known about its transmission dynamics and population genetic structure. Here we sequenced cox1 to quantify genetic variation and the factors that limit gene flow in a 300km 2 area in South Africa. Three quarters of the genetic variation, was explained by differences between worms from the same host, whereas a quarter of the variation was explained by differences between worms from different hosts. With the help of a newly derived model we conclude that while the offspring from different infrapopulations mixes fairly frequently in new hosts, the level of admixture is not enough to homogenize the parasite populations among dogs. Small infrapopulation sizes along with clumped transmission may also result in members of infrapopulations being closely related.

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Applying evolutionary genetics to schistosome epidemiology

Cited by 48 publications

References 140 publications

Inbreeding within human Schistosoma mansoni: do host-specific factors shape the genetic composition of parasite populations?

Inbreeding within human Schistosoma mansoni: do host-specific factors shape the genetic composition of parasite populations?

Molecular epidemiology, phylogeny and evolution of the filarial nematode Wuchereria bancrofti

High within-host genetic variation of the nematode Spirocerca lupi in a high-density urban dog population

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