Population genetics of African Schistosoma species

Abstract

Blood flukes within the genus Schistosoma (schistosomes) are responsible for the major disease, schistosomiasis, in tropical and sub-tropical areas. This disease is predominantly present on the African continent with more than 85% of the human cases. Schistosomes are also parasites of veterinary importance infecting livestock and wildlife. Schistosoma population genetic structure and diversity are important characteristics that may reflect variations in selection pressures such as those induced by host (mammalian and snail) environments, habitat change, migration and also treatment / control interventions, all of which also shape speciation and evolution of the whole Schistosoma genus. Investigations intoschistosome population genetic structure, diversity and evolution has been an area of important debate and research.Supported by advancesin molecular techniques with capabilitiesfor multi-locus genetic analyses for single larvae schistosome geneticinvestigations have greatly progressed in the last decade. This paper aims to review the genetic studies of both animal and human infecting schistosome. Population genetic structures are reviewed at different spatial scales: local, regional or continental (i.e. phylogeography). Within species genetic diversities are discussed compared and the compounding factors discussed, including the effect of mass drug administration. Finally, the ability for intra-species hybridisation questions species integrities and poses many questions in relation to the natural epidemiology of co-endemic species. Here we review molecularly confirmed hybridisation events (in relation to human disease) and discuss the possible impact for ongoing and future control and elimination.

Synergistic effect of combination chemotherapy with praziquantel and DW-3-15 for Schistosoma japonicum in vitro and in vivo

“…Human schistosomiasis is an important neglected disease in tropical and subtropical areas [ 25 ]. PZQ is the first-choice drug available for the treatment of schistosomiasis and has been used extensively for mass administration and transmission control in the absence of alternative drugs [ 26 ].…”

Hybridized Zoonotic Schistosoma Infections Result in Hybridized Morbidity Profiles: A Clinical Morbidity Study amongst Co-Infected Human Populations of Senegal

“…All individual miracidia were classified as hybrids using both ITS and cox1 genotyping simultaneously (samples with only one of the two mitochondrial or nuclear ribosomal measures amplifying were discarded as inconclusive and/or to prevent potential bias regarding hybridizing directionality). Although the combined cox1 -ITS approach lacks the precision to reveal the full history of hybrid populations and may miss highly backcrossed or introgressed hybrid lineages relative to genomic approaches [ 35 ], it has been repeatedly used to successfully identify various stages of hybridization in natural populations and has the advantage of allowing larger scale sampling [ 23 , 25 , 26 , 27 , 36 ]. Furthermore, as early generation hybrids might be more virulent and causing more severe or atypical morbidity [ 3 , 37 , 38 ], this method is particularly relevant here in the context of our study.…”

Genome-wide insights into adaptive hybridisation across the Schistosoma haematobium group in West and Central Africa

“…haematobium group, combined with overlapping host species ranges, inter-species hybridisation within the is not uncommon. Studies by Rollinson et al [ 3 ] report laboratory crosses, whilst Webster et al [ 4 ] detected field-derived hybrids from endemic settings [ 5 , 6 ]. The presence of hybrids is of particular importance when considering disease control, as current intervention policy indicates a shift from morbidity control to transmission interruption [ 7 ].…”