94 research outputs found

    Effect of temperature and relative humidity on the development times and survival of Synopsyllus fonquerniei and Xenopsylla cheopis, the flea vectors of plague in Madagascar

    Get PDF
    Acknowledgements We would like to thank Dr Lila Rahalison and Jocelyn Ratovonjato for their advice and help during the experiment. We are grateful to the staff of the Plague Unit and the Medical Entomology Unit at the Institut Pasteur de Madagascar, particularly Dr Nohal Elissa. Without their expertise this study would not have been possible. Sincere thanks to Mr Tojo Ramihangihajason for his technical assistance. We are indebted to the Institut Pasteur de Madagascar for an internal grant which facilitated additional laboratory research. Two Wellcome Trust fellowships supported ST during this work (081705 and 095171).Peer reviewedPublisher PD

    The vicious circle and infection intensity: The case of Trypanosoma microti in field vole populations

    Get PDF
    Objective: In natural populations, infection and condition may act synergistically to trigger a vicious circle: poor condition predisposes to host infections, which further reduce condition, and so on. If this vicious circle originates from a reduced resistance to infection, it will not only result in greater proneness to becoming infected of those that are in poorer condition, but it may also cause infections of higher intensity. Here, we investigate the temporal relationship between host condition and intensity of infection by a specific pathogen using as a system the dynamics of the protozoan Trypanosoma microti in field vole (Microtus agrestis) populations. Methods and results: With two years of longitudinal data from three monthly-sampled populations, we evaluated if individuals acquiring a high intensity of infection previously had lower haematological indicators of condition (red blood cells [RBCs] and lymphocyte counts) than those that acquired lower infection intensities. Also, the association of these indicators with past and present trypanosome blood levels was investigated. The individuals that developed high levels of parasitaemia were those that previously had low lymphocyte counts. Greater intensity of infection corresponded with lower RBCs only in low to moderate weight females, and no effect of intensity of infection on lymphocyte counts was observed. However, delayed effects of high trypanosome intensity were seen on both RBCs and lymphocytes. Conclusions: The vicious circle may also result in high infection intensity: individuals in poor condition are not only more likely to become infected by one pathogen; they may also be the most important source of infection for that and for other pathogens, and thus key protagonists for parasite dynamics.Fil: Beldomenico, Pablo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Instituto de Ciencias Veterinarias del Litoral; ArgentinaFil: Telfer, Sandra. University of Liverpool; Reino UnidoFil: Gebert, Stephanie. University of Liverpool; Reino UnidoFil: Lukomski, Lukasz. University of Liverpool; Reino UnidoFil: Bennett, Malcolm. University of Liverpool; Reino UnidoFil: Begon, Michael. University of Liverpool; Reino Unid

    Spatial analyses of wildlife contact networks

    Get PDF
    We thank Kathy Horadam for useful discussions about the graph dissimilarity measures and Meggan Craft for reading an early draft of the manuscript and for her helpful advice and encouragement.Peer reviewedPublisher PD

    Molecular and serological evidence of flea-associated typhus group and spotted fever group rickettsial infections in Madagascar

    Get PDF
    This research was supported by the Wellcome Trust (RCDF and Senior Fellowship to ST, #081705 and #095171), the Institut Pasteur de Madagascar, and the Global Emerging Infections Surveillance and Response System, a Division of the Armed Forces Health Surveillance Center [847705.82000.25GB.A0074].Peer reviewedPublisher PD

    Multi-locus sequence analyses reveal a clonal L. borgpetersenii genotype in a heterogeneous invasive Rattus spp. community across the City of Johannesburg, South Africa

    Get PDF
    Funding Information: This study was made possible by a Royal Society for Tropical Medicine and Hygiene small grant (MM, Grant Number GR000556), by a Biotechnology and Biological Sciences Research Council (BBSRC) PhD studentship (MM, Grant Number BB/M010996/1) and by support from the Wellcome Trust (MM, Grant Number 216634/Z/19/Z) . Rodent genotyping was funded through the Centers for Disease Control and Prevention (CDC) Cooperative Agreement (AB, Grant Number 5 NU2GGH001874-02-00) and a Facility Grant (UID78566) from the National Research Foundation of South Africa.Peer reviewedPublisher PD

    A Non-Stationary Relationship between Global Climate Phenomena and Human Plague Incidence in Madagascar

    Get PDF
    Acknowledgments We thank the Plague and Immunology Unit at the Institut Pasteur de Madagascar for data collection and management and supporting the study. Funding The analysis of the study was supported by the Leverhulme Trust Research Leadership Award F/0025/AC: ‘‘Predicting the effects of climate change on infectious diseases of animals’’ (awarded to MB). Funding for KSK was provided by a University of Liverpool PhD studentship award and for MB by BBSRC award ISIS 1813, ‘‘Climate change and the future of plague in Madagascar.’’ The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

    Poor condition and infection: a vicious circle in natural populations

    Get PDF
    Pathogens may be important for host population dynamics, as they can be a proximate cause of morbidity and mortality. Infection dynamics, in turn, may be dependent on the underlying condition of hosts. There is a clear potential for synergy between infection and condition: poor condition predisposes to host infections, which further reduce condition and so on. To provide empirical data that support this notion, we measured haematological indicators of infection (neutrophils and monocytes) and condition (red blood cells (RBCs) and lymphocytes) in field voles from three populations sampled monthly for 2 years. Mixed-effect models were developed to evaluate two hypotheses, (i) that individuals with low lymphocyte and/or RBC levels are more prone to show elevated haematological indicators of infection when re-sampled four weeks later, and (ii) that a decline in indicators of condition is likely to follow the development of monocytosis or neutrophilia. We found that individuals with low RBC and lymphocyte counts had increased probabilities of developing monocytosis and higher increments in neutrophils, and that high indices of infection (neutrophilia and monocytosis) were generally followed by a declining tendency in the indicators of condition (RBCs and lymphocytes). The vicious circle that these results describe suggests that while pathogens overall may be more important in wildlife dynamics than has previously been appreciated, specific pathogens are likely to play their part as elements of an interactive web rather than independent entities

    Reproductive ecology of the black rat (Rattus rattus) in Madagascar : the influence of density-dependent and -independent effects

    Get PDF
    Funding Information: We are grateful to the technical and research staff from the Institut Pasteur de Madagascar and Association Vahatra for fieldwork assistance during this study. K.S. was supported by the Biotechnology and Biological Sciences Research Council (BBSRC) under the EastBio DTP [grant number BB/M010996/1]. This work was also supported by the Wellcome Trust [095171/Z/10/Z]; the Medical Research Council [MR/T029862/1]; and by the National Institute for Health Research (NIHR) (using the UK's Official Development Assistance [ODA] Funding) and Wellcome [219532/Z/19/Z] under the NIHR‐Wellcome Partnership for Global Health Research. The views expressed are those of the authors and not necessarily those of Wellcome, the NIHR, or the Department of Health and Social Care. For the purpose of Open Access, the authors have applied a CC BY license to any author accepted manuscript version arising. Research Funding Biotechnology and Biological Sciences Research Council (BBSRC) under the East-Bio DTP. Grant Number: BB/M010996/1 Wellcome TrustBiotechnology. Grant Number: 095171/Z/10/Z the Medical Research Council. Grant Number: MR/T029862/1 the National Institute for Health Research (NIHR) UK’s Official Development Assistance [ODA] Wellcome. Grant Number: 219532/Z/19/ZPeer reviewedPublisher PD

    Rodent control to fight plague : field assessment of methods based on rat density reduction

    Get PDF
    Research funding: Directorate General for International Relations and Strategy. Grant Number: 2018‐SB‐024‐18SSEOC049‐PMG7‐SSA5‐IPMMADAGASCAR ACKNOWLEDGMENTS: We are especially grateful to the health authorities and the population in Miantso and Ankazobe for allowing us to do this work and being so helpful. We thank the staff of the Plague Unit, Institut Pasteur de Madagascar, for helping with the field and laboratory work, especially Alain Berthin Rakotoarisoa and Andrianiaina Parfait Rakotonindrainy. This work was supported by a Directorate General for International Relations and Strategy grant (2018‐SB‐024‐18SSEOC049‐PMG7‐SSA5‐IPMMADAGASCAR) covering the project “Développement de contre‐mesures médicales à la peste à Madagascar” with scientific support of IRBA (French Armed Forces Biomedical Research Institute), within the framework of French MoD's involvement in G7 Global partnership. The French Agency for International Technical Expertise (AFETI) ensures the proper financial execution of the project and contributes to the implementation of cooperation actions under the control of the Directorate General for International Relations and Strategy. This research was also funded in part by the Wellcome Trust [095171/Z/10/Z] and the Institut Pasteur de Madagascar. For the purpose of Open Access, the authors have applied a CC BY public copyright license to any Author Accepted Manuscript version arising from this submission. K.S. was supported by the Biotechnology and Biological Sciences Research Council (BBSRC) under the EastBio DTP (grant number BB/M010996/1).Peer reviewedPublisher PD

    Geographical distribution and relative risk of Anjozorobe virus (Thailand orthohantavirus) infection in black rats (Rattus rattus) in Madagascar

    Get PDF
    Acknowledgements We thank those who facilitated the survey: householders, heads of fokontany, local administration and health authorities from Ministry of Health. We would like to express our gratitude to the staff of the Plague Central Laboratory Unit, Institut Pasteur de Madagascar: Dr. Minoarisoa Rajerison who facilitated this study; Corinne Rahaingosoamamitiana and Soanandrasana Rahelinirina for helping to conduct and organize the field work. We would also like to thank Dr. Fanjasoa Rakotomanana and Dr. Lalaina Arivony Nomenjanahary assistance in the field trips and technical and field support. Funding This work was supported by the Institut Pasteur de Madagascar (Internal Project through ZORA: Zoonoses, Rodent and Arboviruses) and Wellcome Trust Fellowships to ST (#081705, #095171). VR was also supported though Girard’s fellowship undergraduate program from the Institut Pasteur de Madagascar. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD
    corecore