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Douchet P, Gourbal B, Loker ES, Rey O. Schistosoma transmission: scaling-up competence from hosts to ecosystems. Trends Parasitol 2023; 39:563-574. [PMID: 37120369 PMCID: PMC10880732 DOI: 10.1016/j.pt.2023.04.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/28/2023] [Accepted: 04/04/2023] [Indexed: 05/01/2023]
Abstract
In a One-Health context, it is urgent to establish the links between environmental degradation, biodiversity loss, and the circulation of pathogens. Here we review and literally draw a general vision of aquatic environmental factors that interface with Schistosoma species, agents of schistosomiasis, and ultimately modulate their transmission at the ecosystem scale. From this synthesis, we introduce the concept of ecosystem competence defined as 'the propensity of an ecosystem to amplify or mitigate an incoming quantity of a given pathogen that can be ultimately transmitted to their definitive hosts'. Ecosystem competence integrates all mechanisms at the ecosystem scale underlying the transmission risk of a given pathogen and offers a promising measure for operationalizing the One-Health concept.
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Affiliation(s)
- Philippe Douchet
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via Domitia, Perpignan, France
| | - Benjamin Gourbal
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via Domitia, Perpignan, France
| | - Eric S Loker
- Center for Evolutionary and Theoretical Immunology (CETI), Parasite Division - Museum of Southwestern Biology, Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Olivier Rey
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via Domitia, Perpignan, France.
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2
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Carpenter SA, Vannatta JT, Minchella DJ. Host exposure history and priority effects impact the development and reproduction of a dominant parasite. Int J Parasitol 2021; 51:935-943. [PMID: 34044004 DOI: 10.1016/j.ijpara.2021.03.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 03/12/2021] [Accepted: 03/17/2021] [Indexed: 11/16/2022]
Abstract
Within a single organism, numerous parasites often compete for space and resources. This competition, together with a parasite's ability to locate and successfully establish in a host, can contribute to the distribution and prevalence of parasites. Coinfection with trematodes in snail intermediate hosts is rarely observed in nature, partly due to varying competitive abilities among parasite taxa. Using a freshwater snail host (Biomphalaria glabrata), we studied the ability of a competitively dominant trematode, Echinostoma caproni, to establish and reproduce in a host previously infected with a less competitive trematode species, Schistosoma mansoni. Snails were exposed to S. mansoni and co-exposed to E. caproni either simultaneously or 1 week, 4 weeks, or 6 weeks post S. mansoni exposure. Over the course of infection, we monitored the competitive success of the dominant trematode through infection prevalence, parasite development time, and parasite reproductive output. Infection prevalence of E. caproni did not differ among co-exposed groups or between co-exposed and single exposed groups. However, E. caproni infections in co-exposed hosts took longer to reach maturity when the timing between co-exposures increased. All co-exposed groups had higher E. caproni reproductive output than single exposures. We show that although timing of co-exposure affects the development time of parasite transmission stages, it is not important for successful establishment. Additionally, co-exposure, but not priority effects, increases the reproductive output of the dominant parasite.
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Affiliation(s)
- S A Carpenter
- Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907, USA.
| | - J T Vannatta
- Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907, USA
| | - D J Minchella
- Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907, USA
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Anderson LC, Loker ES, Wearing HJ. Modeling schistosomiasis transmission: the importance of snail population structure. Parasit Vectors 2021; 14:94. [PMID: 33536054 PMCID: PMC7860629 DOI: 10.1186/s13071-021-04587-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 01/08/2021] [Indexed: 12/14/2022] Open
Abstract
Background Schistosomiasis is a neglected tropical disease endemic in 54 countries. A major Schistosoma species, Schistosoma mansoni, is sustained via a life cycle that includes both human and snail hosts. Mathematical models of S. mansoni transmission, used to elucidate the complexities of the transmission cycle and estimate the impact of intervention efforts, often focus primarily on the human host. However, S. mansoni incurs physiological costs in snails that vary with the age of the snail when first infected. Snail demography and the age of snail infection could thus affect the force of infection experienced by humans, which is frequently used to predict the impact of various control strategies. Methods To address how these snail host and parasite interactions influence model predictions, we developed deterministic models of schistosomiasis transmission that include varying complexity in the snail population age structure. Specifically, we examined how model outputs, such as schistosome prevalence in human and snail populations, respond to the inclusion of snail age structure. Results Our models suggest that snail population age structure modifies the force of infection experienced by humans and the relationship between snail infection prevalence and corresponding human infection prevalence. There are significant differences in estimated snail infection, cercarial density and mean worm burden between models without snail population dynamics and those with snail populations, and between models with a homogeneous snail population and those with age stratification. The variation between finely age-stratified snail populations and those grouped into only juvenile and adult life stages is, however, minimal. Conclusions These results indicate that including snails and snail age structure in a schistosomiasis transmission model alters the relationship between snail and human infection prevalence. This highlights the importance of accounting for a heterogeneous intermediate host population in models of schistosomiasis transmission where the impact of proposed control measures is being considered.![]()
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Affiliation(s)
- Larissa C Anderson
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA.
| | - Eric S Loker
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Helen J Wearing
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA.,Department of Mathematics and Statistics, University of New Mexico, Albuquerque, NM, 87131, USA
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Mouahid G, Mintsa Nguema R, Al Mashikhi KM, Al Yafae SA, Idris MA, Moné H. Host-parasite life-histories of the diurnal vs. nocturnal chronotypes of Schistosoma mansoni: adaptive significance. Trop Med Int Health 2019; 24:692-700. [PMID: 30851235 DOI: 10.1111/tmi.13227] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To optimise host-to-host transmission, digenean trematodes (parasites) synchronise their cercarial emission patterns with the aquatic activities of their vertebrate hosts. Schistosoma mansoni has two different circadian chronotypes: a diurnal shedding pattern with a mean peak occurring at 11:00 h, and a nocturnal shedding pattern with a mean peak occurring at 20:00 h. We analysed the life-history variations between these two chronotypes at the levels of the parasite and its hosts. METHODS For each chronotype, we quantified three life-history traits related to the parasite (prepatent period, infection rate and cercarial production) and analysed the morphometry and the morphology of the parasite eggs; we also quantified three life-history traits related to the snail intermediate host (shell diameter, fecundity and survival rate) and one life-history trait related to the experimental definitive host (survival rate). A phylogeny based on the mitochondrial cytochrome-oxidase gene was made on samples of both chronotypes. RESULTS Life-history analysis revealed significant variations between the two chronotypes. Life-history traits were optimal for both the parasite and the snail host for the diurnal chronotype compared to the nocturnal one. The new chronotype behaved like an allopatric population towards its snail host. Phylogenetic analysis supports the hypothesis of a lateral transfer of S. mansoni from humans to Rattus rattus. These results were interpreted in terms of an ongoing sympatric speciation. CONCLUSION The nocturnal chronotype of S. mansoni showed non-adapted life-history traits in its relation with the snail intermediate host Biomphalaria pfeifferi. The emergence of this new phenotype is probably linked to divergent natural selection.
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Affiliation(s)
- Gabriel Mouahid
- IHPE Laboratory, UMR5244, UM, CNRS, IFREMER, University of Perpignan Via Domitia, Perpignan, France
| | | | | | - Salem A Al Yafae
- Directorate General of Health Services, Salalah, Sultanate of Oman
| | - Mohamed A Idris
- Department of Microbiology and Immunology, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Sultanate of Oman
| | - Hélène Moné
- IHPE Laboratory, UMR5244, UM, CNRS, IFREMER, University of Perpignan Via Domitia, Perpignan, France
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Civitello DJ, Fatima H, Johnson LR, Nisbet RM, Rohr JR. Bioenergetic theory predicts infection dynamics of human schistosomes in intermediate host snails across ecological gradients. Ecol Lett 2018. [PMID: 29527787 DOI: 10.1111/ele.12937] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Epidemiological dynamics depend on the traits of hosts and parasites, but hosts and parasites are heterogeneous entities that exist in dynamic environments. Resource availability is a particularly dynamic and potent environmental driver of within-host infection dynamics (temporal patterns of growth, reproduction, parasite production and survival). We developed, parameterised and validated a model for resource-explicit infection dynamics by incorporating a parasitism module into dynamic energy budget theory. The model mechanistically explained the dynamic multivariate responses of the human parasite Schistosoma mansoni and its intermediate host snail to variation in resources and host density. At the population level, feedbacks mediated by resource competition could create a unimodal relationship between snail density and human risk of exposure to schistosomes. Consequently, weak snail control could backfire if reductions in snail density release remaining hosts from resource competition. If resource competition is strong and relevant to schistosome production in nature, it could inform control strategies.
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Affiliation(s)
- David J Civitello
- Department of Biology, Emory University, 1510 Clifton Rd NE, 30322, Atlanta, GA, USA
| | - Hiba Fatima
- Global Health Institute, Duke University, Durham, NC, USA
| | - Leah R Johnson
- Department of Statistics, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Roger M Nisbet
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, UCSB, 93106, Santa Barbara, CA, USA
| | - Jason R Rohr
- Department of Integrative Biology, University of South Florida, 4202, East Fowler Ave., 33620, Tampa, FL, USA
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Mouahid G, Rognon A, de Carvalho Augusto R, Driguez P, Geyer K, Karinshak S, Luviano N, Mann V, Quack T, Rawlinson K, Wendt G, Grunau C, Moné H. Transplantation of schistosome sporocysts between host snails: A video guide. Wellcome Open Res 2018; 3:3. [PMID: 29487916 PMCID: PMC5806052 DOI: 10.12688/wellcomeopenres.13488.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2018] [Indexed: 01/10/2023] Open
Abstract
Schistosomiasis is an important parasitic disease, touching roughly 200 million people worldwide. The causative agents are different
Schistosoma species. Schistosomes have a complex life cycle, with a freshwater snail as intermediate host. After infection, sporocysts develop inside the snail host and give rise to human dwelling larvae. We present here a detailed step-by-step video instruction in English, French, Spanish and Portuguese that shows how these sporocysts can be manipulated and transferred from one snail to another. This procedure provides a technical basis for different types of
ex vivo modifications, such as those used in functional genomics studies.
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Affiliation(s)
- Gabriel Mouahid
- Laboratoire Interactions Hôtes-Pathogènes-Environnements (IHPE), UMR 5244 CNRS/UPVD/IFREMER/UM, University of Perpignan Via Domitia, 58 Avenue Paul Alduy, Bât R, F-66860 Perpignan Cedex, France
| | - Anne Rognon
- Laboratoire Interactions Hôtes-Pathogènes-Environnements (IHPE), UMR 5244 CNRS/UPVD/IFREMER/UM, University of Perpignan Via Domitia, 58 Avenue Paul Alduy, Bât R, F-66860 Perpignan Cedex, France
| | - Ronaldo de Carvalho Augusto
- Laboratoire Interactions Hôtes-Pathogènes-Environnements (IHPE), UMR 5244 CNRS/UPVD/IFREMER/UM, University of Perpignan Via Domitia, 58 Avenue Paul Alduy, Bât R, F-66860 Perpignan Cedex, France
| | - Patrick Driguez
- Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, UK
| | - Kathy Geyer
- Institute of Biological, Environmental and Rural Sciences , Aberystwyth University, Aberystwyth, UK
| | - Shannon Karinshak
- Department of Microbiology, Immunology & Tropical Medicine, George Washington University Medical Center, Washington, DC, USA
| | - Nelia Luviano
- Laboratoire Interactions Hôtes-Pathogènes-Environnements (IHPE), UMR 5244 CNRS/UPVD/IFREMER/UM, University of Perpignan Via Domitia, 58 Avenue Paul Alduy, Bât R, F-66860 Perpignan Cedex, France
| | - Victoria Mann
- Department of Microbiology, Immunology & Tropical Medicine, George Washington University Medical Center, Washington, DC, USA
| | - Thomas Quack
- Institut für Parasitologie, Justus-Liebig-Universität Gießen, Gießen, Germany
| | - Kate Rawlinson
- Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, UK.,Department of Zoology, University of Cambridge, Downing St, Cambridge, UK
| | - George Wendt
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Christoph Grunau
- Laboratoire Interactions Hôtes-Pathogènes-Environnements (IHPE), UMR 5244 CNRS/UPVD/IFREMER/UM, University of Perpignan Via Domitia, 58 Avenue Paul Alduy, Bât R, F-66860 Perpignan Cedex, France
| | - Hélène Moné
- Laboratoire Interactions Hôtes-Pathogènes-Environnements (IHPE), UMR 5244 CNRS/UPVD/IFREMER/UM, University of Perpignan Via Domitia, 58 Avenue Paul Alduy, Bât R, F-66860 Perpignan Cedex, France
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Soldánová M, Selbach C, Sures B. The Early Worm Catches the Bird? Productivity and Patterns of Trichobilharzia szidati Cercarial Emission from Lymnaea stagnalis. PLoS One 2016; 11:e0149678. [PMID: 26895541 PMCID: PMC4760985 DOI: 10.1371/journal.pone.0149678] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 02/02/2016] [Indexed: 11/18/2022] Open
Abstract
Digenean trematodes are common and abundant in aquatic habitats and their free-living larvae, the cercariae, have recently been recognized as important components of ecosystems in terms of comprising a significant proportion of biomass and in having a potentially strong influence on food web dynamics. One strategy to enhance their transmission success is to produce high numbers of cercariae which are available during the activity peak of the next host. In laboratory experiments with 13 Lymnaea stagnalis snails infected with Trichobilharzia szidati the average daily emergence rate per snail was determined as 2,621 cercariae, with a maximum of 29,560. During a snail’s lifetime this summed up to a mass equivalent of or even exceeding the snail’s own body mass. Extrapolated for the eutrophic pond where the snails were collected, annual T. szidati biomass may reach 4.65 tons, a value equivalent to a large Asian elephant. Emission peaks were observed after the onset of illumination, indicating emission synchronizing with the high morning activities of the definitive hosts, ducks. However, high cercarial emission is possible throughout the day under favorable lightning conditions. Therefore, although bird schistosomes, such as T. szidati constitute only a fraction of the diverse trematode communities in the studied aquatic ecosystem, their cercariae can still pose a considerable risk for humans of getting cercarial dermatitis (swimmer's itch) due to the high number of cercariae emitted from infected snails.
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Affiliation(s)
- Miroslava Soldánová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech Republic
- * E-mail:
| | - Christian Selbach
- Department of Aquatic Ecology and Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Essen, Germany
| | - Bernd Sures
- Department of Aquatic Ecology and Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Essen, Germany
- Department of Zoology, University of Johannesburg, Johannesburg, South Africa
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Théron A. Chronobiology of trematode cercarial emergence: from data recovery to epidemiological, ecological and evolutionary implications. ADVANCES IN PARASITOLOGY 2015; 88:123-64. [PMID: 25911367 DOI: 10.1016/bs.apar.2015.02.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
One major challenge for parasites with complex cycles consists to succeed in the transmission from one host to the next host. To maximize the probability of encountering the right host, numerous trematode species have selected various emergence rhythms occurring during the escape of the short-lived cercariae from the mollusc host. Cercarial shedding patterns are beautiful examples of adaptation of the parasite for a successful rendezvous with its subsequent host. In this review, after an analysis of the technical and statistical aspects specific to such studies, we compile the knowledge and unresolved issues we have about the synchronization of these rhythms, their genetic support and the role of the host physiology or activity. We are also interested on how cercarial rhythmicity influences cercarial densities in waters of transmission sites and then the risk of host infection in case of schistosomiasis. Ecological significance of the inter- and intra-specific diversity of these rhythms is emphasized as well as the evolutionary implication of new chronotypes resulting from the capture of new host species and promoting reproductive isolation and alloxenic speciation. Currently, genome sequence data now available for some trematodes such as the schistosomes provide an unprecedented resource for new research approaches that should contribute identification of the genes and mechanisms involved in determining the cercarial shedding rhythms observed.
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Affiliation(s)
- André Théron
- CNRS, UMR 5244, Ecologie et Evolution des Interactions (2EI), Université de Perpignan Via Domitia, Université, Perpignan, France.
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Sympatric and allopatric experimental infections of the planorbid snail Gyraulus chinensis with miracidia of Euparyphium albuferensis (Trematoda: Echinostomatidae). J Helminthol 2010; 84:420-4. [PMID: 20236558 DOI: 10.1017/s0022149x10000143] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An experimental infection with echinostomatid miracidia in sympatric or 'local' vs. allopatric or 'away' snail combinations, as a model to examine parasite compatibility, was carried out. We employed Euparyphium albuferensis miracidia to infect Gyraulus chinensis snails, from three different natural parks: Albufera (Valencia, Spain); the Ebro Delta (Tarragona, Spain) and Coto de Doñana (Huelva, Spain). Insignificant differences between the three snail strains were noted for the infection rate and the rhythm of daily cercarial production. However, a significantly higher total cercarial production per snail, patent period and life span were observed in local snails. The different infection characteristics in the three G. chinensis strains considered reveal that E. albuferensis miracidia demonstrate local adaptation.
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The effects of host size and temperature on the emergence of Echinoparyphium recurvatum cercariae from Lymnaea peregra under natural light conditions. J Helminthol 2010; 84:317-26. [PMID: 20078900 DOI: 10.1017/s0022149x09990666] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The production of cercariae from their snail host is a fundamental component of transmission success in trematodes. The emergence of Echinoparyphium recurvatum (Trematoda: Echinostomatidae) cercariae from Lymnaea peregra was studied under natural sunlight conditions, using naturally infected snails of different sizes (10-17 mm) within a temperature range of 10-29 degrees C. There was a single photoperiodic circadian cycle of emergence with one peak, which correlated with the maximum diffuse sunlight irradiation. At 21 degrees C the daily number of emerging cercariae increased with increasing host snail size, but variations in cercarial emergence did occur between both individual snails and different days. There was only limited evidence of cyclic emergence patterns over a 3-week period, probably due to extensive snail mortality, particularly those in the larger size classes. Very few cercariae emerged in all snail size classes at the lowest temperature studied (10 degrees C), but at increasingly higher temperatures elevated numbers of cercariae emerged, reaching an optimum between 17 and 25 degrees C. Above this range emergence was reduced. At all temperatures more cercariae emerged from larger snails. Analysis of emergence using the Q10 value, a measure of physiological processes over temperature ranges, showed that between 10 and 21 degrees C (approximately 15 degrees C) Q10 values exceeded 100 for all snail size classes, indicating a substantially greater emergence than would be expected for normal physiological rates. From 14 to 25 degrees C (approximately 20 degrees C) cercarial emergence in most snail size classes showed little change in Q10, although in the smallest size class emergence was still substantially greater than the typical Q10 increase expected over this temperature range. At the highest range of 21-29 degrees C (approximately 25 degrees C), Q10 was much reduced. The importance of these results for cercarial emergence under global climate change is discussed.
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Steinauer ML, Mwangi IN, Maina GM, Kinuthia JM, Mutuku MW, Agola EL, Mungai B, Mkoji GM, Loker ES. Interactions between natural populations of human and rodent schistosomes in the Lake Victoria region of Kenya: a molecular epidemiological approach. PLoS Negl Trop Dis 2008; 2:e222. [PMID: 18414646 PMCID: PMC2291567 DOI: 10.1371/journal.pntd.0000222] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Accepted: 03/10/2008] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Schistosoma mansoni exists in a complex environmental milieu that may select for significant evolutionary changes in this species. In Kenya, the sympatric distribution of S. mansoni with S. rodhaini potentially influences the epidemiology, ecology, and evolutionary biology of both species, because they infect the same species of snail and mammalian hosts and are capable of hybridization. METHODOLOGY/PRINCIPAL FINDINGS Over a 2-year period, using a molecular epidemiological approach, we examined spatial and temporal distributions, and the overlap of these schistosomes within snails, in natural settings in Kenya. Both species had spatially and temporally patchy distributions, although S. mansoni was eight times more common than S. rodhaini. Both species were overdispersed within snails, and most snails (85.2% for S. mansoni and 91.7% for S. rodhaini) only harbored one schistosome genotype. Over time, half of snails infected with multiple genotypes showed a replacement pattern in which an initially dominant genotype was less represented in later replicates. The other half showed a consistent pattern over time; however, the ratio of each genotype was skewed. Profiles of circadian emergence of cercariae revealed that S. rodhaini emerges throughout the 24-hour cycle, with peak emergence before sunrise and sometimes immediately after sunset, which differs from previous reports of a single nocturnal peak immediately after sunset. Peak emergence for S. mansoni cercariae occurred as light became most intense and overlapped temporally with S. rodhaini. Comparison of schistosome communities within snails against a null model indicated that the community was structured and that coinfections were more common than expected by chance. In mixed infections, cercarial emergence over 24 hours remained similar to single species infections, again with S. rodhaini and S. mansoni cercarial emergence profiles overlapping substantially. CONCLUSIONS/SIGNIFICANCE The data from this study indicate a lack of obvious spatial or temporal isolating mechanisms to prevent hybridization, raising the intriguing question of how the two species retain their separate identities.
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Richards CS, Knight M, Lewis FA. Genetics of Biomphalaria glabrata and its effect on the outcome of Schistosoma mansoni infection. ACTA ACUST UNITED AC 2005; 8:171-4. [PMID: 15463608 DOI: 10.1016/0169-4758(92)90015-t] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The genetics of the snail Biomphalaria glabrata is better characterized than that of any other intermediate host of schistosomes of humans. Using techniques of selective breeding, several snail stocks have been developed that consistently display resistant or susceptible phenotypes. Investigators using these stocks have learned that several snail and parasite genes influence the course of parasite development. Here, Charles Richards, Matty Knight and Fred Lewis discuss the importance of the snail's genetics in categorizing resistance in this complex invertebrate, some recent molecular evidence that may help us understand several of the problems that still remain, and some challenges lying ahead for investigators in this field.
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Affiliation(s)
- C S Richards
- Biomedical Research Institute, 12111 Parklawn Drive, Rockville, MD 20852, USA
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13
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Abstract
Schistosomes are unusual, together with some of the didymozoidae, in that they are dioecious instead of being hermaphrodite. This gonochorism is accompanied with morphological, ecological, behavioural and molecular differences between the male and the female parasites all through their life cycle. This review is an overview of the sexual biology of schistosomes and aims to provide the most recent information that may help to build future control strategies against these parasites. It proposes a new view of the life cycle of schistosomes, taking into account the sexual status of each developmental stage. It presents the relevant information available on the genetic and phenotypic sexual dimorphisms of these parasites; it proposes a comparison between the host-male parasite and the host-female parasite interactions in both the molluscan intermediate and the mammalian definitive hosts; it exposes the male-female parasite interactions that exist in both the mollusc and the mammalian hosts at the parasite individual and populational levels. This review highlights the domains of research that are still unexplored but that would be of great interest for a better knowledge of the sexual way of life of the parasites which are still responsible for one of the most important human parasitic diseases in the world.
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Affiliation(s)
- Hélène Moné
- Laboratoire de Parasitologie Fonctionnelle et Evolutive, UMR 5555 CNRS-UP, Centre de Biologie et d'Ecologie Tropicale et Méditerranéenne, Université, 566860 Perpignan Cedex, France
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Boissier J, Moné H. Male-female larval interactions in Schistosoma mansoni-infected Biomphalaria glabrata. Int J Parasitol 2001; 31:352-8. [PMID: 11306113 DOI: 10.1016/s0020-7519(01)00119-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
This paper investigates Schistosoma mansoni male-female larval interactions in simultaneous bi-miracidial Biomphalaria glabrata infections. Larval interactions were analysed at four levels of infection: (i), miracidial infectivity, estimated by the prevalence of mollusc infection; (ii), mollusc pathology, measured by the mollusc growth and survival; (iii), dynamics of the cercarial sex ratio; and (iv), cercarial infectivity, measured as the success of development into adulthood. Our results showed that larval interactions exist in S. mansoni-infected B. glabrata. These interactions do not occur in miracidial infectivity, but occur in mollusc pathology, cercarial sex ratio dynamics and cercarial infectivity. Regarding mollusc pathology, we showed that the bi-miracidially-infected molluscs were smaller than the mono-miracidially-infected ones. This could be the result of larval competition. Regarding the dynamics of the cercarial sex ratio, we showed larval female superiority as compared with male larvae inducing the shedding of female-biased cercarial sex ratios. These sex ratios were rhythmic and could be the reflection of an external expression of the intramolluscan development. Regarding cercarial infectivity, we showed that the simultaneous presence of both sexes in a mollusc increased the cercarial infectivity. This result could be due to male-female larval synergism.
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Affiliation(s)
- J Boissier
- Centre de Biologie et d'Ecologie Tropicale et Méditerranéenne (UMR 5555 CNRS-Université), Université de Perpignan, 52 Avenue de Villeneuve, 66860 Perpignan Cedex, France
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15
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Van Gompel A, Van den Enden E, Van den Ende J, Geerts S. Laboratory infection with Schistosoma mansoni. Trans R Soc Trop Med Hyg 1993; 87:554. [PMID: 8266408 DOI: 10.1016/0035-9203(93)90086-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Affiliation(s)
- A Van Gompel
- Outpatients Department, Institute of Tropical Medicine, Antwerp, Belgium
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16
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Théron A, Moné H, Gérard C. Spatial and energy compromise between host and parasite: the Biomphalaria glabrata-Schistosoma mansoni system. Int J Parasitol 1992; 22:91-4. [PMID: 1563925 DOI: 10.1016/0020-7519(92)90084-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The development of a sporocyst infrapopulation of Schistosoma mansoni within the Biomphalaria glabrata snail is, from a spatial point of view, detrimental to the host's digestive-genital gland complex growth. For mono- and plurimiracidial infections, the digestive gland volumes are, respectively 51 and 24% of those of control snails. Identical reduction of the infected genital gland volume (43% of controls) occurs in both cases. After the prepatent period, the ratio of parasite/digestive gland volumes (P/PDG) remains fairly constant at around 0.60 independent of the miracidial dose infection, indicative of a balanced host-parasite development which is discussed in relation to the spatial and energy constraints of this system.
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Affiliation(s)
- A Théron
- Laboratoire de Biologie Animale, URA CNRS 698, Perpignan, France
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17
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Théron A, Gérard C, Moné H. Early enhanced growth of the digestive gland of Biomphalaria glabrata infected with Schistosoma mansoni: side effect or parasite manipulation? Parasitol Res 1992; 78:445-50. [PMID: 1495925 DOI: 10.1007/bf00931703] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We carried out a comparative study of the dynamics of the sporocyst population and the growth rate of the host habitat (digestive and genital gland) within the Schistosoma mansoni/Biomphalaria glabrata system during monomiracidial infections. The volume of the digestive gland increased sharply during the first 2 weeks of infection and then decreased at 2-4 weeks post-infection during the exponential growth phase of the sporocyst infrapopulation. The effects of the parasite on the development of the host's genital gland resulted in a slowing of the growth of the ovotestis. These interactions, related to the demographic processes involved in the intramolluscal development of the parasite population, were interpreted in relation to the spatial and energy constraints imposed by the developmental needs of both the parasite and the host.
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Affiliation(s)
- A Théron
- Laboratoire de Biologie Animale, URA CNRS 698, Perpignan, France
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18
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Niemann GM, Lewis FA. Schistosoma mansoni: influence of Biomphalaria glabrata size on susceptibility to infection and resultant cercarial production. Exp Parasitol 1990; 70:286-92. [PMID: 2311711 DOI: 10.1016/0014-4894(90)90110-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Biomphalaria glabrata snails of the same age, but different sizes, were used to determine size-related susceptibility to Schistosoma mansoni miracidial infection and the influence of snail size on total cercarial production. Snails with shell diameters from less than 5 to greater than 17 mm were individually exposed to one or several miracidia, depending on the experiment. In snails exposed to multiple numbers of miracidia, the percentage of snails which developed patent infections was lower in snails with larger shell sizes. This was also reflected by fewer primary sporocysts per infected snail found in tissues of the larger snails. Upon determining cercarial production in these groups over a 1-month period there were no statistical differences between any groups in the numbers of cercariae produced per snail. However, upon determining the number of successful primary sporocysts found in cohort snails of each size group, cercarial production increased as a function of the number of successful primary sporocysts. This was verified by examining cercarial production in various size snails with known monomiracidial infections. Our data therefore confirm and extend earlier work using snails infected with unknown numbers of miracidia and clearly show that total S. mansoni cercarial development and decreased susceptibility of snails is a direct reflection of snail size and not necessarily age of the snail.
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Affiliation(s)
- G M Niemann
- Biomedical Research Institute, Rockville, Maryland 20852
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19
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Kechemir N, Théron A. Dynamics of the intramolluscan larval development of Schistosoma haematobium: replication of daughter sporocysts and cercarial production. J Helminthol 1989; 63:1-5. [PMID: 2723382 DOI: 10.1017/s0022149x00008634] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
During the intramolluscan larval development of Schistosoma haematobium (Algerian strain) in Bulinus truncatus, two replication processes of daughter sporocysts occur. Replication by direct sporocystogenesis appears more important than sporocystogenesis post cercariogenesis. These mechanisms assure a periodic renewal of the sporocyst stock in the snail host and seem to be synchronized with the development of cercarial generations. The succession of several generations of cercariae is responsible for the alternation of high and low periods of productivity. The scheme proposed for the intramolluscan development of S. haemtobium is compared with those described for S. mansoni and S. bovis and interpreted in terms of demographic strategies adapted to a better exploitation of the snail host.
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Affiliation(s)
- N Kechemir
- Service de Parasitologie, Institut Pasteur d'Algérie, Alger
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20
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Théron A, Touassem R. Schistosoma rodhaini: intramolluscan larval development, migration and replication processes of daughter sporocysts. Acta Trop 1989; 46:39-45. [PMID: 2566260 DOI: 10.1016/0001-706x(89)90014-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The larval development of Schistosoma rodhaini in Biomphalaria glabrata presents two features of interest. The first concerns the migration of daughter sporocysts: only a fraction of the daughter sporocysts produced by the mother sporocyst migrate directly towards the digestive gland of the snail and become cercariogenous; the others remain in the anterior region of the snail where the majority transforms into small sporocystogenous sporocysts. The second point concerns the replication processes: only direct replication of daughter sporocysts was observed in sporocysts in a prehepatic localization. The demographic processes involved in the development of S. rodhaini are compared with other species of Schistosoma and interpreted as an adaptive character for better exploitation of the snail host.
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Affiliation(s)
- A Théron
- Centre de Biologie et d'Ecologie tropicale et méditerranéenne, Université, Perpignan, France
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21
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Fryer SE, Probert AJ. The cercarial output from three Nigerian bulinids infected with two strains of Schistosoma haematobium. J Helminthol 1988; 62:133-40. [PMID: 3397515 DOI: 10.1017/s0022149x00011378] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The daily cercarial output of two Nigerian strains of Schistosoma haematobium in sympatric Bulinus truncatus, B. globosus and B. senegalensis was measured at weekly intervals from the start of emission to the snails' death. In all cases cercariae were released throughout the life of the host, with no cases of "self cure". Patterns of output through the course of infections in B. truncatus and B. senegalensis were similar to those reported for S. haematobium by other workers, with daily production of cercariae rising to a peak within a few weeks of the onset of shedding, then declining until the host's death. In the longer lived B. globosus production was significantly higher, but declined to very low levels after the initial peak; in some individuals cercarial output remained very low, while others showed a second period of high cercarial emission. The relative compatibility of each host-parasite combination is discussed.
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Affiliation(s)
- S E Fryer
- School of Animal Biology, University College of North Wales, Bangor, Gwynedd
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22
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Mouahid A, Théron A. Schistosoma bovis: variability of cercarial production as related to the snail hosts: Bulinus truncatus, B. wright and Planorbarius metidjensis. Int J Parasitol 1987; 17:1431-4. [PMID: 3440697 DOI: 10.1016/0020-7519(87)90078-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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23
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Affiliation(s)
- A Théron
- Département de Biologie Animale, UA CNRS 698 Université, Av. de Villeneue, 66025 Perpignan Cedex, France
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24
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Schwanbek A, Becker W, Rupprecht H. Quantification of parasite development in the host-parasite system Biomphalaria glabrata and Schistosoma mansoni. ZEITSCHRIFT FUR PARASITENKUNDE (BERLIN, GERMANY) 1986; 72:365-73. [PMID: 3716543 DOI: 10.1007/bf00928747] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The visceral mass of Biomphalaria glabrata uninfected or infected with Schistosoma mansoni was serially sectioned. The amount of hepatopancreas tissue and of parasite tissue was quantified. In pool-infected snails the volume of the whole visceral mass increased very significantly until week 6 and then decreased. Due to the growing parasites the volume of the visceral mass in infected snails was at most times higher when compared with uninfected snails of the same dimensions. Two weeks p.i. there was a permanent and significant increase of parasite tissue until week 6. During this time the amount of hepatopancreas tissue still increased. From this time onwards till week 12 the proportion of parasite tissue remained rather constant, indicating a kind of regulation, whereas the hepatopancreas tissue decreased to about one-third of the volume found in uninfected snails of the same shell diameter. Compared with infections by a single miracidium there was a significant increase in parasite tissue after infection with two miracidia. Infections with more miracidia (5, 10, and 20) gave no significant further increase. This also demonstrates a kind of regulation. Mortality rate, growth rate and egg production were studied during an infection period of 12 weeks.
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25
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Fournier A, Théron A. [Morpho-anatomic and functional sectorization of Schistosoma mansoni daughter sporocysts]. ZEITSCHRIFT FUR PARASITENKUNDE (BERLIN, GERMANY) 1985; 71:325-36. [PMID: 4013468 DOI: 10.1007/bf00928335] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
During the larval development of S. mansoni in the snail host, morpho-anatomic changes occur in the daughter sporocyst by a sectorization of this larval stage. Three sectors can be distinguished: an anterior zone with a well-differentiated birth pore; dilated zones containing the developing cercariae; constricted zones without cercarial embryo. The photonic and electronic microscopical study shows variations in the tegumental structure of these sectors. This evolution of the daughter sporocysts is discussed in relation with the dynamics of larval stages and the replication process of sporocysts.
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26
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Théron A, Moné H. Chronobiological aspects of the host-parasite relationships between Biomphalaria glabrata and Schistosoma mansoni: cercarial production and infectivity, and growth kinetics of the host. J Invertebr Pathol 1984; 44:209-13. [PMID: 6501917 DOI: 10.1016/0022-2011(84)90014-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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27
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Becker W. Purine metabolism in Biomphalaria glabrata under starvation and infection with Schistosoma mansoni. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1983; 76:215-9. [PMID: 6641159 DOI: 10.1016/0305-0491(83)90061-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Purine content and its alterations during a starvation period of 29 days and an infection period of 52 days were studied. During starvation the amount of uric acid increased from 2.11 +/- 0.95 mg/g dry wt in control snails to a maximum of 6.73 +/- 3.99 mg/g dry wt on day 29 of starvation for uric acid and from 4.73 +/- 2.10 mg/g dry wt in control snails to a maximum of 11.29 +/- 3.48 mg/g dry wt on day 23 of starvation for guanine. During infection there was an increase with both uric acid and guanine to maximum on day 40 post infection (7.17 +/- 3.51 mg/g dry wt for uric acid, 14.83 +/- 4.53 mg/g dry wt for guanine) and a decrease afterwards. Of all the snails' organs tested, only in the kidney were purines detectable, but it was impossible to find excreted purines.
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