Other affiliations: Medical Research Council
Bio: P.J. Moore is an academic researcher from British Museum. The author has contributed to research in topics: Schistosomiasis. The author has an hindex of 1, co-authored 2 publications receiving 54 citations. Previous affiliations of P.J. Moore include Medical Research Council.
TL;DR: Viable hybrid parasites were produced in the laboratory and were maintained up until the F4 generation, Comparisons of egg morphology, surface structure of adult male worms and enzyme profiles have been made between experimental hybrid lines and field isolates.
Abstract: Surveys of 332 naturally infected bovines at eight abattoirs in Senegal, The Gambia and Mali were carried out to determine the prevalence of infection with Schistosoma bovis and S. curassoni and to pinpoint areas where the distribution of the species overlap. S. bovis was the commonest schistosome of cattle in Senegal and Mali being found in animals at seven abattoirs, the highest prevalance of 85.1% occurred at Mopti in Mali. S. bovis was the only bovine schistosome observed in The Gambia. S. curassoni was isolated from a cow at Bamako and shown to have similar glucose-6-phosphate dehydrogenase, phosphoglucomutase and acid phosphatase profiles to those described for a Senegalese isolate. Evidence of interaction of S. bovis with S. curassoni was found in cattle from Senegal, at Tambacounda and Kolda, and from Mali, at Bamako and Mopti. A mixed experimental infection of both species in a sheep showed the lack of any specific mate recognition system: identification of the worms was facilitated by analysis of acid phosphatase by isoelectric focusing in polyacrylamide gels. Viable hybrid parasites were produced in the laboratory and were maintained up until the F4 generation. Comparisons of egg morphology, surface structure of adult male worms and enzyme profiles have been made between experimental hybrid lines and field isolates. Possible mechanisms maintaining species integrity are discussed.
TL;DR: In this article, nuclear and mitochondrial markers revealed unexpected natural interactions between a bovine and human Schistosoma species: S. bovis and S. haematobium.
Abstract: Schistosomiasis is a disease of great medical and veterinary importance in tropical and subtropical regions, caused by parasitic flatworms of the genus Schistosoma (subclass Digenea). Following major water development schemes in the 1980s, schistosomiasis has become an important parasitic disease of children living in the Senegal River Basin (SRB). During molecular parasitological surveys, nuclear and mitochondrial markers revealed unexpected natural interactions between a bovine and human Schistosoma species: S. bovis and S. haematobium, respectively. Hybrid schistosomes recovered from the urine and faeces of children and the intermediate snail hosts of both parental species, Bulinus truncatus and B. globosus, presented a nuclear ITS rRNA sequence identical to S. haematobium, while the partial mitochondrial cox1 sequence was identified as S. bovis. Molecular data suggest that the hybrids are not 1st generation and are a result of parental and/or hybrid backcrosses, indicating a stable hybrid zone. Larval stages with the reverse genetic profile were also found and are suggested to be F1 progeny. The data provide indisputable evidence for the occurrence of bidirectional introgressive hybridization between a bovine and a human Schistosoma species. Hybrid species have been found infecting B. truncatus, a snail species that is now very abundant throughout the SRB. The recent increase in urinary schistosomiasis in the villages along the SRB could therefore be a direct effect of the increased transmission through B. truncatus. Hybridization between schistosomes under laboratory conditions has been shown to result in heterosis (higher fecundity, faster maturation time, wider intermediate host spectrum), having important implications on disease prevalence, pathology and treatment. If this new hybrid exhibits the same hybrid vigour, it could develop into an emerging pathogen, necessitating further control strategies in zones where both parental species overlap.
TL;DR: These data provide indisputable evidence for: the high occurrence of bidirectional hybridization between these Schistosoma species; the first conclusive evidence for the natural hybridisation between S. haematobium and S. curassoni; and demonstrate that the transmission of the different species and their hybrids appears focal.
Abstract: Background Schistosomes are dioecious parasitic flatworms, which live in the vasculature of their mammalian definitive hosts. They are the causative agent of schistosomiasis, a disease of considerable medical and veterinary importance in tropical and subtropical regions. Schistosomes undergo a sexual reproductive stage within their mammalian host enabling interactions between different species, which may result in hybridization if the species involved are phylogenetically close. In Senegal, three closely related species in the Schistosoma haematobium group are endemic: S. haematobium, which causes urogenital schistosomiasis in humans, and S. bovis and S. curassoni, which cause intestinal schistosomiasis in cows, sheep and goats.
TL;DR: This paper adds to previous phylogenetic studies on the family Schistosomatidae and offers the most up to date and robust phylogeny of the group based on complete small and large nuclear subunit rRNA genes and partial mitochondrial cox1, incorporating most of the 21 species of SchistOSoma.
Abstract: In light of the recently described human schistosome Schistosoma guineensis and recent phylogenetic studies of the genus Schistosoma, a revision of the interrelationships of the members of this genus is needed. This paper adds to previous phylogenetic studies on the family Schistosomatidae and offers the most up to date and robust phylogeny of the group based on complete small and large nuclear subunit rRNA genes and partial mitochondrial cox1, incorporating most of the 21 species of Schistosoma. Our findings show that the group retains the same topology as that resolved in previous studies except Schistosoma margrebowiei was resolved as the sister taxon to all others in the Schistosoma haematobium species group and S. guineensis was placed as sister species to both Schistosoma bovis and Schistosoma curassoni. The S. haematobium species group contains eight species of which many are of significant medical and veterinary importance. Additionally, many of these species have been shown to hybridise both in the wild and experimentally, making the correct identification and recognition of species very important. A pairwise comparison of cox1 among Schistosoma species suggests this gene alone would fail as a reliable barcode for species identification. Phylogenetic results clearly treat Schistosoma intercalatum and S. guineensis as separate taxa with each more closely related evolutionarily to S. haematobium than to each other. The study also highlights the problems associated with wrongly attributed sequences on public databases such as GenBank.
TL;DR: Hybridization of parasites is an emerging public health concern at the interface of infectious disease biology and evolution and can allow for heterospecific (between-species or between-lineage) mate pairings, resulting in parthenogenesis and whole-genome admixture.
Abstract: Hybridization of parasites is an emerging public health concern at the interface of infectious disease biology and evolution. Increasing economic development, human migration, global trade, and climate change are all shifting the geographic distribution of existing human, livestock, companion animal, and wildlife parasites [1–9]. As a result, human populations encounter new infections more frequently, and coinfection by multiple parasites from different lineages or species within individual hosts occurs. Coinfection may have a large impact on the hosts and parasites involved, often as a result of synergistic or antagonistic interactions between parasites . Indeed, mixed-species coinfections have been found to influence parasite establishment, growth, maturation, reproductive success, and/or drug efficacy [11–13]. However, coinfections can allow for heterospecific (between-species or between-lineage) mate pairings, resulting in parthenogenesis (asexual reproduction in which eggs occur without fertilization), introgression (the introduction of single genes or chromosomal regions from one species into that of another through repeated backcrossing), and whole-genome admixture through hybridization .
TL;DR: The aim here is to highlight the importance of both elucidating disease ecology, including identifying key hosts and tailoring control effort accordingly, and understanding parasite evolution, such as precisely how infectious agents may respond and adapt to anthropogenic change.
Abstract: Understanding the complex population biology and transmission ecology of multihost parasites has been declared as one of the major challenges of biomedical sciences for the 21st century and the Neglected Zoonotic Diseases (NZDs) are perhaps the most neglected of all the Neglected Tropical Diseases (NTDs). Here we consider how multihost parasite transmission and evolutionary dynamics may affect the success of human and animal disease control programmes, particularly neglected diseases of the developing world. We review the different types of zoonotic interactions that occur, both ecological and evolutionary, their potential relevance for current human control activities, and make suggestions for the development of an empirical evidence base and theoretical framework to better understand and predict the outcome of such interactions. In particular, we consider whether preventive chemotherapy, the current mainstay of NTD control, can be successful without a One Health approach. Transmission within and between animal reservoirs and humans can have important ecological and evolutionary consequences, driving the evolution and establishment of drug resistance, as well as providing selective pressures for spill-over, host switching, hybridizations and introgressions between animal and human parasites. Our aim here is to highlight the importance of both elucidating disease ecology, including identifying key hosts and tailoring control effort accordingly, and understanding parasite evolution, such as precisely how infectious agents may respond and adapt to anthropogenic change. Both elements are essential if we are to alleviate disease risks from NZDs in humans, domestic animals and wildlife.