1
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Nie Y, Zhong X, Lin T, Wang W. Pathogen diversity in meta-population networks. CHAOS, SOLITONS, AND FRACTALS 2023; 166:112909. [PMID: 36467017 PMCID: PMC9699689 DOI: 10.1016/j.chaos.2022.112909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 09/15/2022] [Accepted: 11/13/2022] [Indexed: 06/17/2023]
Abstract
The pathogen diversity means that multiple strains coexist, and widely exist in the biology systems. The new mutation of SARS-CoV-2 leading to worldwide pathogen diversity is a typical example. What are the main factors of inducing the pathogen diversity? Previous studies indicated the pathogen mutation is the most important reason for inducing the pathogen diversity. The traffic network and gene network are crucial in shaping the dynamics of pathogen contagion, while their roles for the pathogen diversity still lacking a theoretical study. To this end, we propose a reaction-diffusion process of pathogens with mutations on meta-population networks, which includes population movement and strain mutation. We extend the Microscopic Markov Chain Approach (MMCA) to describe the model. Traffic networks make pathogen diversity more likely to occur in cities with lower infection densities. The likelihood of pathogen diversity is low in cities with short effective distances in the traffic network. Star-type gene network is more likely to lead to pathogen diversity than lattice-type and chain-type gene networks. When pathogen localization is present, infection is localized to strains that are at the endpoints of the gene network. Both the increased probability of movement and mutation promote pathogen diversity. The results also show that the population tends to move to cities with short effective distances, resulting in the infection density is high.
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Affiliation(s)
- Yanyi Nie
- School of Public Health, Chongqing Medical University, Chongqing, 400016, China
- College of Computer Science, Sichuan University, Chengdu 610065, China
| | - Xiaoni Zhong
- School of Public Health, Chongqing Medical University, Chongqing, 400016, China
| | - Tao Lin
- College of Computer Science, Sichuan University, Chengdu 610065, China
| | - Wei Wang
- School of Public Health, Chongqing Medical University, Chongqing, 400016, China
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2
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Sieben AJ, Mihaljevic JR, Shoemaker LG. Quantifying mechanisms of coexistence in disease ecology. Ecology 2022; 103:e3819. [PMID: 35855596 DOI: 10.1002/ecy.3819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/22/2022] [Accepted: 04/20/2022] [Indexed: 11/06/2022]
Abstract
Pathogen coexistence depends on ecological processes operating at both within and between-host scales, making it difficult to quantify which processes may promote or prevent coexistence. Here, we propose that adapting modern coexistence theory-traditionally applied in plant communities-to pathogen systems provides an exciting approach for examining mechanisms of coexistence operating across different spatial scales. We first overview modern coexistence theory and its mechanistic decomposition; we subsequently adapt the framework to quantify how spatial variation in pathogen density, host resources and immunity, and their interaction may promote pathogen coexistence. We apply this derivation to an example two pathogen, multi-scale model comparing two scenarios with generalist and strain-specific immunity: one with demographic equivalency among pathogens and one with demographic trade-offs among pathogens. We then show how host-pathogen feedbacks generate spatial heterogeneity that promote pathogen coexistence and decompose those mechanisms to quantify how each spatial heterogeneity contributes to that coexistence. Specifically, coexistence of demographically equivalent pathogens occurs due to spatial variation in host resources, immune responses, and pathogen aggregation. With a competition-colonization trade-off, the superior colonizer requires spatial heterogeneity to coexist, whereas the superior competitor does not. Finally, we suggest ways forward for linking theory and empirical tests of coexistence in disease systems.
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Affiliation(s)
- Andrew J Sieben
- Department of Botany, University of Wyoming, Laramie, WY.,School of Medicine, Emory University, Atlanta, GA
| | - Joseph R Mihaljevic
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ
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3
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Eck JL, Barrès B, Soubeyrand S, Sirén J, Numminen E, Laine AL. Strain Diversity and Spatial Distribution Are Linked to Epidemic Dynamics in Host Populations. Am Nat 2022; 199:59-74. [DOI: 10.1086/717179] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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4
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Thao Le TM, Madec S, Gjini E. Disentangling how multiple traits drive 2 strain frequencies in SIS dynamics with coinfection. J Theor Biol 2022; 538:111041. [DOI: 10.1016/j.jtbi.2022.111041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 12/01/2021] [Accepted: 01/18/2022] [Indexed: 10/19/2022]
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5
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Paediatric assessment of immune responses in 3 to 5 years olds having intestinal nematode infection and vaccinated with valent10-PCV. SCIENTIFIC AFRICAN 2021. [DOI: 10.1016/j.sciaf.2021.e00863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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6
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Tomaszewski E, Jennings M, Munk B, Botta R, Lewison R. Landscape Seroprevalence of Three Hemorrhagic Disease-Causing Viruses in a Wild Cervid. ECOHEALTH 2021; 18:182-193. [PMID: 34515899 DOI: 10.1007/s10393-021-01546-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 05/02/2021] [Accepted: 05/14/2021] [Indexed: 06/13/2023]
Abstract
Disease plays a major role in shaping wildlife populations worldwide, and changes in landscape conditions can significantly influence risk of pathogen exposure, a threat to vulnerable wild species. Three viruses that cause hemorrhagic disease affect cervid populations in the USA (Odocoileus hemionus adenovirus, bluetongue virus, and epizootic hemorrhagic disease virus), but little is known of their distribution and prevalence in wild populations. We explored the distribution and co-occurrence of seroprevalence of these three pathogens in southern mule deer (Odocoileus hemionus fuliginatus), a subspecies of conservation concern and a harvested species native to southern California, to evaluate the distribution of exposure to these pathogens relative to landscape attributes. We found that habitat type, level of development, and proximity to livestock may affect hemorrhagic disease seroprevalence in southern mule deer. Continued monitoring of hemorrhagic disease-causing viruses in areas where deer are in proximity to cattle and human development is needed to better understand the implications of future outbreaks in wild populations and to identify opportunities to mitigate disease impacts in southern mule deer and other cervid species.
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Affiliation(s)
- Emma Tomaszewski
- San Diego State University, 5500 Campanile Dr., San Diego, CA, 92182, USA.
- California Department of Fish and Wildlife, 1416 9th St., 12th Floor, Sacramento, CA, 95814, USA.
| | - Megan Jennings
- San Diego State University, 5500 Campanile Dr., San Diego, CA, 92182, USA
| | - Brandon Munk
- California Department of Fish and Wildlife, 1416 9th St., 12th Floor, Sacramento, CA, 95814, USA
| | - Randy Botta
- California Department of Fish and Wildlife, 1416 9th St., 12th Floor, Sacramento, CA, 95814, USA
| | - Rebecca Lewison
- San Diego State University, 5500 Campanile Dr., San Diego, CA, 92182, USA
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7
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Nouri M, Latorre-Margalef N, Czopek A, Råberg L. Cross-reactivity of antibody responses to Borrelia afzelii OspC: Asymmetry and host heterogeneity. INFECTION GENETICS AND EVOLUTION 2021; 91:104793. [PMID: 33652116 DOI: 10.1016/j.meegid.2021.104793] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 02/08/2021] [Accepted: 02/25/2021] [Indexed: 11/27/2022]
Abstract
The tick-transmitted bacterium Borrelia afzelii consists of a number of antigenically different strains - often defined by outer surface protein C (OspC) genotype - that coexist at stable frequencies in host populations. To investigate how host antibody responses affect strain coexistence, we measured antibody cross-reactivity to three different OspC types (OspC 2, 3 and 9) in three different strains of laboratory mice (BALB/c, C3H and C57BL/6). The extent of cross-reactivity differed between mouse strains, being higher in C3H than BALB/c and C57BL/6. In one of three pairwise comparisons of OspC types (OspC2 vs OspC9), there was evidence for asymmetry of cross-reactivity, with antibodies to OspC2 cross-reacting more strongly with OspC9 than vice versa. These results indicate that the extent of antibody-mediated competition between OspC types may depend on the composition of the host population, and that such competition may be asymmetric. We discuss the implications of these results for understanding the coexistence of OspC types.
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Affiliation(s)
- Mehrnaz Nouri
- Department of Biology, Lund University, Sölvegatan 35, 223 62 Lund, Sweden
| | - Neus Latorre-Margalef
- Department of Biology and Environmental Sciences, Linnaeus University, 391 82 Kalmar, Sweden
| | - Agnieszka Czopek
- Department of Biology, Lund University, Sölvegatan 35, 223 62 Lund, Sweden
| | - Lars Råberg
- Department of Biology, Lund University, Sölvegatan 35, 223 62 Lund, Sweden.
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8
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Newcombe G, Fraser SJ, Ridout M, Busby PE. Leaf Endophytes of Populus trichocarpa Act as Pathogens of Neighboring Plant Species. Front Microbiol 2020; 11:573056. [PMID: 33281769 PMCID: PMC7705171 DOI: 10.3389/fmicb.2020.573056] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 09/15/2020] [Indexed: 11/22/2022] Open
Abstract
The conventional definition of endophytes is that they do not cause disease, whereas pathogens do. Complicating this convention, however, is the poorly explored phenomenon that some microbes are endophytes in some plants but pathogens in others. Black cottonwood or poplar (Populus trichocarpa) and wheat (Triticum aestivum) are common wild and crop plants, respectively, in the Pacific Northwest USA. The former anchors wild, riparian communities, whereas the latter is an introduced domesticate of commercial importance in the region. We isolated Fusarium culmorum – a well-known pathogen of wheat causing both blight and rot – from the leaf of a black cottonwood tree in western Washington. The pathogenicity of this cottonwood isolate and of a wheat isolate of F. culmorum were compared by inoculating both cottonwood and wheat in a greenhouse experiment. We found that both the cottonwood and wheat isolates of F. culmorum significantly reduced the growth of wheat, whereas they had no impact on cottonwood growth. Our results demonstrate that the cottonwood isolate of F. culmorum is endophytic in one plant species but pathogenic in another. Using sequence-based methods, we found an additional 56 taxa in the foliar microbiome of cottonwood that matched the sequences of pathogens of other plants of the region. These sequence-based findings suggest, though they do not prove, that P. trichocarpa may host many additional pathogens of other plants.
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Affiliation(s)
- George Newcombe
- Department of Forest, Rangeland, and Fire Sciences, College of Natural Resources, University of Idaho, Moscow, ID, United States
| | - Shannon J Fraser
- Department of Forest, Rangeland, and Fire Sciences, College of Natural Resources, University of Idaho, Moscow, ID, United States
| | - Mary Ridout
- College of Agriculture and Life Sciences, University of Idaho Extension Washington County, Weiser, ID, United States
| | - Posy E Busby
- Department of Botany and Plant Pathology, College of Agricultural Sciences, Oregon State University, Corvallis, OR, United States
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9
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Madec S, Gjini E. Predicting N-Strain Coexistence from Co-colonization Interactions: Epidemiology Meets Ecology and the Replicator Equation. Bull Math Biol 2020; 82:142. [PMID: 33119836 PMCID: PMC7595998 DOI: 10.1007/s11538-020-00816-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 09/30/2020] [Indexed: 01/02/2023]
Abstract
Multi-type infection processes are ubiquitous in ecology, epidemiology and social systems, but remain hard to analyze and to understand on a fundamental level. Here, we study a multi-strain susceptible-infected-susceptible model with coinfection. A host already colonized by one strain can become more or less vulnerable to co-colonization by a second strain, as a result of facilitating or competitive interactions between the two. Fitness differences between N strains are mediated through \documentclass[12pt]{minimal}
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\begin{document}$$N^2$$\end{document}N2 altered susceptibilities to secondary infection that depend on colonizer-cocolonizer identities (\documentclass[12pt]{minimal}
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\begin{document}$$K_{ij}$$\end{document}Kij). By assuming strain similarity in such pairwise traits, we derive a model reduction for the endemic system using separation of timescales. This ‘quasi-neutrality’ in trait space sets a fast timescale where all strains interact neutrally, and a slow timescale where selective dynamics unfold. We find that these slow dynamics are governed by the replicator equation for N strains. Our framework allows to build the community dynamics bottom-up from only pairwise invasion fitnesses between members. We highlight that mean fitness of the multi-strain network, changes with their individual dynamics, acts equally upon each type, and is a key indicator of system resistance to invasion. By uncovering the link between N-strain epidemiological coexistence and the replicator equation, we show that the ecology of co-colonization relates to Fisher’s fundamental theorem and to Lotka-Volterra systems. Besides efficient computation and complexity reduction for any system size, these results open new perspectives into high-dimensional community ecology, detection of species interactions, and evolution of biodiversity.
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Affiliation(s)
- Sten Madec
- Institut Denis Poisson, University of Tours, Tours, France
| | - Erida Gjini
- Instituto Gulbenkian de Ciência, Oeiras, Portugal. .,Center for Computational and Stochastic Mathematics, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal.
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10
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Azarian T, Martinez PP, Arnold BJ, Qiu X, Grant LR, Corander J, Fraser C, Croucher NJ, Hammitt LL, Reid R, Santosham M, Weatherholtz RC, Bentley SD, O’Brien KL, Lipsitch M, Hanage WP. Frequency-dependent selection can forecast evolution in Streptococcus pneumoniae. PLoS Biol 2020; 18:e3000878. [PMID: 33091022 PMCID: PMC7580979 DOI: 10.1371/journal.pbio.3000878] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 09/18/2020] [Indexed: 11/30/2022] Open
Abstract
Predicting how pathogen populations will change over time is challenging. Such has been the case with Streptococcus pneumoniae, an important human pathogen, and the pneumococcal conjugate vaccines (PCVs), which target only a fraction of the strains in the population. Here, we use the frequencies of accessory genes to predict changes in the pneumococcal population after vaccination, hypothesizing that these frequencies reflect negative frequency-dependent selection (NFDS) on the gene products. We find that the standardized predicted fitness of a strain, estimated by an NFDS-based model at the time the vaccine is introduced, enables us to predict whether the strain increases or decreases in prevalence following vaccination. Further, we are able to forecast the equilibrium post-vaccine population composition and assess the invasion capacity of emerging lineages. Overall, we provide a method for predicting the impact of an intervention on pneumococcal populations with potential application to other bacterial pathogens in which NFDS is a driving force.
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Affiliation(s)
- Taj Azarian
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, United States of America
- Center for Communicable Disease Dynamics, Department of Epidemiology, T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, United States of America
| | - Pamela P. Martinez
- Center for Communicable Disease Dynamics, Department of Epidemiology, T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, United States of America
| | - Brian J. Arnold
- Center for Communicable Disease Dynamics, Department of Epidemiology, T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, United States of America
| | - Xueting Qiu
- Center for Communicable Disease Dynamics, Department of Epidemiology, T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, United States of America
| | - Lindsay R. Grant
- Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Jukka Corander
- Helsinki Institute for Information Technology, Department of Mathematics and Statistics, University of Helsinki, Helsinki, Finland
- Department of Biostatistics, University of Oslo, Oslo, Norway
- Infection Genomics, The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, United Kingdom
| | - Christophe Fraser
- Big Data Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Nicholas J. Croucher
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Laura L. Hammitt
- Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Raymond Reid
- Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Mathuram Santosham
- Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Robert C. Weatherholtz
- Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Stephen D. Bentley
- Infection Genomics, The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, United Kingdom
| | | | - Marc Lipsitch
- Center for Communicable Disease Dynamics, Department of Epidemiology, T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, United States of America
- Department of Immunology and Infectious Diseases, T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, United States of America
| | - William P. Hanage
- Center for Communicable Disease Dynamics, Department of Epidemiology, T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, United States of America
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11
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Facilitative priority effects drive parasite assembly under coinfection. Nat Ecol Evol 2020; 4:1510-1521. [PMID: 32868915 DOI: 10.1038/s41559-020-01289-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 07/22/2020] [Indexed: 12/14/2022]
Abstract
Host individuals are often coinfected with diverse parasite assemblages, resulting in complex interactions among parasites within hosts. Within hosts, priority effects occur when the infection sequence alters the outcome of interactions among parasites. Yet, the role of host immunity in this process remains poorly understood. We hypothesized that the host response to the first infection could generate priority effects among parasites, altering the assembly of later-arriving strains during epidemics. We tested this by infecting sentinel host genotypes of Plantago lanceolata with strains of the fungal parasite Podosphaera plantaginis and measuring susceptibility to subsequent infection during experimental and natural epidemics. In these experiments, prior infection by one strain often increased susceptibility to other strains, and these facilitative priority effects altered the structure of parasite assemblages, but this effect depended on host genotype, host population and parasite genotype. Thus, host genotype, spatial structure and priority effects among strains all independently altered parasite assembly. Using a fine-scale survey and sampling of infections on wild hosts in several populations, we then identified a signal of facilitative priority effects, which altered parasite assembly during natural epidemics. Together, these results provide evidence that within-host priority effects of early-arriving strains can drive parasite assembly, with implications for how strain diversity is spatially and temporally distributed during epidemics.
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12
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Ouldali N, Cohen R, Levy C, Gelbert-Baudino N, Seror E, Corrard F, Vie Le Sage F, Michot AS, Romain O, Bechet S, Bonacorsi S, Angoulvant F, Varon E. Pneumococcal susceptibility to antibiotics in carriage: a 17 year time series analysis of the adaptive evolution of non-vaccine emerging serotypes to a new selective pressure environment. J Antimicrob Chemother 2020; 74:3077-3086. [PMID: 31280295 DOI: 10.1093/jac/dkz281] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/21/2019] [Accepted: 06/03/2019] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Pneumococcal conjugate vaccine (PCV) implementations led to major changes in serotype distribution and antibiotic resistance in carriage, accompanied by changes in antibiotic consumption. OBJECTIVES To assess the dynamic patterns of antimicrobial non-susceptibility across non-PCV13 serotypes following PCV implementations. METHODS We conducted a quasi-experimental interrupted time series analysis based on a 17 year French nationwide prospective cohort. From 2001 to 2018, 121 paediatricians obtained nasopharyngeal swabs from children with acute otitis media who were aged 6 months to 2 years. The main outcome was the rate of penicillin-non-susceptible pneumococci (PNSP), analysed by segmented regression. RESULTS We enrolled 10 204 children. After PCV13 implementation, the PNSP rate decreased (-0.5% per month; 95% CI -0.9 to -0.1), then, after 2014, the rate slightly increased (+0.7% per month; 95% CI +0.2 to +1.2). Global antibiotic use within the previous 3 months decreased over the study period (-22.2%; 95% CI -33.0 to -11.3), but aminopenicillin use remained high. Among the main non-PCV13 serotypes, four dynamic patterns of penicillin susceptibility evolution were observed, including unexpected patterns of serotypes emerging while remaining or even becoming penicillin susceptible. In contrast to PNSP strains, for these latter patterns, the rate of co-colonization with Haemophilus influenzae increased concomitant with their emergence. CONCLUSIONS In a context of continuing high antibiotic selective pressure, a progressive increase in PNSP rate was observed after 2014. However, we highlighted an unexpected variability in dynamic patterns of penicillin susceptibility among emerging non-PCV13 serotypes. Antibiotic resistance may not be the only adaptive mechanism to antimicrobial selective pressure, and co-colonization with H. influenzae may be involved.
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Affiliation(s)
- Naim Ouldali
- ACTIV, Association Clinique et Thérapeutique Infantile du Val-de-Marne, Saint Maur-des-Fossés, France.,GPIP, Groupe de Pathologie Infectieuse Pédiatrique, Paris, France.,Unité d'épidémiologie clinique, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, ECEVE INSERM UMR 1123, Paris, France.,Urgences pédiatriques, hôpital Necker Enfants Malades, Université Paris Descartes, Paris, France
| | - Robert Cohen
- ACTIV, Association Clinique et Thérapeutique Infantile du Val-de-Marne, Saint Maur-des-Fossés, France.,GPIP, Groupe de Pathologie Infectieuse Pédiatrique, Paris, France.,AFPA, Association Française de Pédiatrie Ambulatoire, Saint-Germain-en-Laye, France.,Université Paris Est, IMRB-GRC GEMINI, Créteil, France.,Clinical Research Center (CRC), Centre Hospitalier Intercommunal de Créteil, Créteil, Créteil, France.,Unité Court Séjour, Petits nourrissons, Service de Néonatalogie, Centre Hospitalier Intercommunal de Créteil, France
| | - Corinne Levy
- ACTIV, Association Clinique et Thérapeutique Infantile du Val-de-Marne, Saint Maur-des-Fossés, France.,GPIP, Groupe de Pathologie Infectieuse Pédiatrique, Paris, France.,AFPA, Association Française de Pédiatrie Ambulatoire, Saint-Germain-en-Laye, France.,Université Paris Est, IMRB-GRC GEMINI, Créteil, France.,Clinical Research Center (CRC), Centre Hospitalier Intercommunal de Créteil, Créteil, Créteil, France
| | - Nathalie Gelbert-Baudino
- GPIP, Groupe de Pathologie Infectieuse Pédiatrique, Paris, France.,AFPA, Association Française de Pédiatrie Ambulatoire, Saint-Germain-en-Laye, France
| | - Elisa Seror
- ACTIV, Association Clinique et Thérapeutique Infantile du Val-de-Marne, Saint Maur-des-Fossés, France.,Hématologie pédiatrique, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
| | - François Corrard
- ACTIV, Association Clinique et Thérapeutique Infantile du Val-de-Marne, Saint Maur-des-Fossés, France.,AFPA, Association Française de Pédiatrie Ambulatoire, Saint-Germain-en-Laye, France
| | - François Vie Le Sage
- GPIP, Groupe de Pathologie Infectieuse Pédiatrique, Paris, France.,AFPA, Association Française de Pédiatrie Ambulatoire, Saint-Germain-en-Laye, France
| | - Anne-Sylvestre Michot
- ACTIV, Association Clinique et Thérapeutique Infantile du Val-de-Marne, Saint Maur-des-Fossés, France
| | - Olivier Romain
- ACTIV, Association Clinique et Thérapeutique Infantile du Val-de-Marne, Saint Maur-des-Fossés, France.,GPIP, Groupe de Pathologie Infectieuse Pédiatrique, Paris, France.,Réanimation et pédiatrie néonatales, Hôpitaux Universitaires Paris-Sud, Hôpital Antoine Béclère, Clamart, France
| | - Stéphane Bechet
- ACTIV, Association Clinique et Thérapeutique Infantile du Val-de-Marne, Saint Maur-des-Fossés, France.,GPIP, Groupe de Pathologie Infectieuse Pédiatrique, Paris, France.,Université Paris Est, IMRB-GRC GEMINI, Créteil, France
| | - Stéphane Bonacorsi
- Université Paris Diderot, Sorbonne Paris Cité, Paris, France.,Service de Microbiologie, Assistance Publique-Hôpitaux de Paris, Hôpital Robert-Debré, Paris, France
| | - François Angoulvant
- GPIP, Groupe de Pathologie Infectieuse Pédiatrique, Paris, France.,Urgences pédiatriques, hôpital Necker Enfants Malades, Université Paris Descartes, Paris, France.,Centre de recherche des Cordeliers, INSERM UMR 1138, Paris, France
| | - Emmanuelle Varon
- National Reference Center for Pneumococci, Centre Hospitalier Intercommunal de Créteil, Créteil, France
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13
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Chisholm RH, Sonenberg N, Lacey JA, McDonald MI, Pandey M, Davies MR, Tong SYC, McVernon J, Geard N. Epidemiological consequences of enduring strain-specific immunity requiring repeated episodes of infection. PLoS Comput Biol 2020; 16:e1007182. [PMID: 32502148 PMCID: PMC7299408 DOI: 10.1371/journal.pcbi.1007182] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 06/17/2020] [Accepted: 05/11/2020] [Indexed: 11/25/2022] Open
Abstract
Group A Streptococcus (GAS) skin infections are caused by a diverse array of strain types and are highly prevalent in disadvantaged populations. The role of strain-specific immunity in preventing GAS infections is poorly understood, representing a critical knowledge gap in vaccine development. A recent GAS murine challenge study showed evidence that sterilising strain-specific and enduring immunity required two skin infections by the same GAS strain within three weeks. This mechanism of developing enduring immunity may be a significant impediment to the accumulation of immunity in populations. We used an agent-based mathematical model of GAS transmission to investigate the epidemiological consequences of enduring strain-specific immunity developing only after two infections with the same strain within a specified interval. Accounting for uncertainty when correlating murine timeframes to humans, we varied this maximum inter-infection interval from 3 to 420 weeks to assess its impact on prevalence and strain diversity, and considered additional scenarios where no maximum inter-infection interval was specified. Model outputs were compared with longitudinal GAS surveillance observations from northern Australia, a region with endemic infection. We also assessed the likely impact of a targeted strain-specific multivalent vaccine in this context. Our model produced patterns of transmission consistent with observations when the maximum inter-infection interval for developing enduring immunity was 19 weeks. Our vaccine analysis suggests that the leading multivalent GAS vaccine may have limited impact on the prevalence of GAS in populations in northern Australia if strain-specific immunity requires repeated episodes of infection. Our results suggest that observed GAS epidemiology from disease endemic settings is consistent with enduring strain-specific immunity being dependent on repeated infections with the same strain, and provide additional motivation for relevant human studies to confirm the human immune response to GAS skin infection. Group A Streptococcus (GAS) is a ubiquitous bacterial pathogen that exists in many distinct strains, and is a major cause of death and disability globally. Vaccines against GAS are under development, but their effective use will require better understanding of how immunity develops following infection. Evidence from an animal model of skin infection suggests that the generation of enduring strain-specific immunity requires two infections by the same strain within a short time frame. It is not clear if this mechanism of immune development operates in humans, nor how it would contribute to the persistence of GAS in populations and affect vaccine impact. We used a mathematical model of GAS transmission, calibrated to data collected in an Indigenous Australian community, to assess whether this mechanism of immune development is consistent with epidemiological observations, and to explore its implications for the impact of a vaccine. We found that it is plausible that repeat infections are required for the development of immunity in humans, and illustrate the difficulties associated with achieving sustained reductions in disease prevalence with a vaccine.
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Affiliation(s)
- Rebecca H. Chisholm
- Department of Mathematics and Statistics, La Trobe University, Melbourne, Victoria, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - Nikki Sonenberg
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - Jake A. Lacey
- Doherty Department University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Victoria, Australia
| | - Malcolm I. McDonald
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland, Australia
| | - Manisha Pandey
- Institute for Glycomics, Gold Coast Campus, Griffith University, Brisbane, Queensland, Australia
| | - Mark R. Davies
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Steven Y. C. Tong
- Doherty Department University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Victoria, Australia
- Victorian Infectious Diseases Service, The Royal Melbourne Hospital, at the Peter Doherty Institute for Infection and Immunity, Victoria, Australia
- Menzies School of Health Research, Charles Darwin University, Darwin, Australia
| | - Jodie McVernon
- Victorian Infectious Diseases Reference Laboratory Epidemiology Unit at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne and Royal Melbourne Hospital, Victoria, Australia
| | - Nicholas Geard
- Victorian Infectious Diseases Reference Laboratory Epidemiology Unit at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne and Royal Melbourne Hospital, Victoria, Australia
- School of Computing and Information Systems, Melbourne School of Engineering, The University of Melbourne, Melbourne, Victoria, Australia
- * E-mail:
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14
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Pinotti F, Ghanbarnejad F, Hövel P, Poletto C. Interplay between competitive and cooperative interactions in a three-player pathogen system. ROYAL SOCIETY OPEN SCIENCE 2020; 7:190305. [PMID: 32218925 PMCID: PMC7029927 DOI: 10.1098/rsos.190305] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 12/13/2019] [Indexed: 06/10/2023]
Abstract
In ecological systems, heterogeneous interactions between pathogens take place simultaneously. This occurs, for instance, when two pathogens cooperate, while at the same time, multiple strains of these pathogens co-circulate and compete. Notable examples include the cooperation of human immunodeficiency virus with antibiotic-resistant and susceptible strains of tuberculosis or some respiratory infections with Streptococcus pneumoniae strains. Models focusing on competition or cooperation separately fail to describe how these concurrent interactions shape the epidemiology of such diseases. We studied this problem considering two cooperating pathogens, where one pathogen is further structured in two strains. The spreading follows a susceptible-infected-susceptible process and the strains differ in transmissibility and extent of cooperation with the other pathogen. We combined a mean-field stability analysis with stochastic simulations on networks considering both well-mixed and structured populations. We observed the emergence of a complex phase diagram, where the conditions for the less transmissible, but more cooperative strain to dominate are non-trivial, e.g. non-monotonic boundaries and bistability. Coupled with community structure, the presence of the cooperative pathogen enables the coexistence between strains by breaking the spatial symmetry and dynamically creating different ecological niches. These results shed light on ecological mechanisms that may impact the epidemiology of diseases of public health concern.
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Affiliation(s)
- Francesco Pinotti
- INSERM, Sorbonne Université, Institut Pierre Louis d’Épidémiologie et de Santé Publique, IPLESP, Paris 75012, France
| | - Fakhteh Ghanbarnejad
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, Berlin 10623, Germany
- The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy
- Physics Department, Sharif University of Technology, PO Box 11165-9161, Tehran, Iran
| | - Philipp Hövel
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, Berlin 10623, Germany
- School of Mathematical Sciences, University College Cork, Western Road, Cork T12 XF62, Republic of Ireland
| | - Chiara Poletto
- INSERM, Sorbonne Université, Institut Pierre Louis d’Épidémiologie et de Santé Publique, IPLESP, Paris 75012, France
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15
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Rynkiewicz EC, Fenton A, Pedersen AB. Linking community assembly and structure across scales in a wild mouse parasite community. Ecol Evol 2019; 9:13752-13763. [PMID: 31938479 PMCID: PMC6953566 DOI: 10.1002/ece3.5785] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 08/23/2019] [Accepted: 09/21/2019] [Indexed: 01/03/2023] Open
Abstract
Understanding what processes drive community structure is fundamental to ecology. Many wild animals are simultaneously infected by multiple parasite species, so host-parasite communities can be valuable tools for investigating connections between community structures at multiple scales, as each host can be considered a replicate parasite community. Like free-living communities, within-host-parasite communities are hierarchical; ecological interactions between hosts and parasites can occur at multiple scales (e.g., host community, host population, parasite community within the host), therefore, both extrinsic and intrinsic processes can determine parasite community structure. We combine analyses of community structure and assembly at both the host population and individual scales using extensive datasets on wild wood mice (Apodemus sylvaticus) and their parasite community. An analysis of parasite community nestedness at the host population scale provided predictions about the order of infection at the individual scale, which were then tested using parasite community assembly data from individual hosts from the same populations. Nestedness analyses revealed parasite communities were significantly more structured than random. However, observed nestedness did not differ from null models in which parasite species abundance was kept constant. We did not find consistency between observed community structure at the host population scale and within-host order of infection. Multi-state Markov models of parasite community assembly showed that a host's likelihood of infection with one parasite did not consistently follow previous infection by a different parasite species, suggesting there is not a deterministic order of infection among the species we investigated in wild wood mice. Our results demonstrate that patterns at one scale (i.e., host population) do not reliably predict processes at another scale (i.e., individual host), and that neutral or stochastic processes may be driving the patterns of nestedness observed in these communities. We suggest that experimental approaches that manipulate parasite communities are needed to better link processes at multiple ecological scales.
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Affiliation(s)
- Evelyn C. Rynkiewicz
- Department of Science and MathematicsFashion Institute of TechnologyState University of New YorkNew YorkNYUSA
- Institute of Evolutionary Biology & Centre for Immunity, Infection and EvolutionSchool of Biological ScienceUniversity of EdinburghEdinburghUK
| | - Andy Fenton
- Institute of Integrative BiologyUniversity of LiverpoolLiverpoolUK
| | - Amy B. Pedersen
- Institute of Evolutionary Biology & Centre for Immunity, Infection and EvolutionSchool of Biological ScienceUniversity of EdinburghEdinburghUK
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16
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Pathirana NUK, Meegaskumbura M, Rajakaruna RS. Infection sequence alters disease severity-Effects of the sequential exposure of two larval trematodes to Polypedates cruciger tadpoles. Ecol Evol 2019; 9:6220-6230. [PMID: 31236216 PMCID: PMC6580301 DOI: 10.1002/ece3.5180] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 12/25/2018] [Accepted: 01/02/2019] [Indexed: 11/10/2022] Open
Abstract
Multiple pathogens coexist in nature, and hence, host species often encounter several pathogens simultaneously. The sequence in which the host encounters the parasites influences interactions between parasites and host pathology. Here, the effects of infection by two cercaria (larvae of trematodes) types, pleurolophocercous cercaria of Acanthostomum burminis and a furcocercous cercaria, on the tadpoles of common hourglass tree frog (Polypedates cruciger) were examined. Ten days posthatch, tadpoles (Gosner stage 27/28) were used for infection exposures. First, in a single infection each cercaria type was introduced to the tadpoles separately. Second, coinfection of the two cercaria was carried out by alternating the sequences of exposure. For all the experiments, appropriate controls were instituted. Tadpoles of all groups exposed to parasites had lower survival levels compared to controls. Among the four groups exposed, the highest survival was observed in the coinfection when furcocercous was introduced first (82.5%). The lowest survival was observed in the coinfection when the A. burminis cercaria was introduced first (65.0%). In the coinfections, when A. burminis was introduced prior to furcocercous, survival of the tadpoles was reduced by 17.0% compared to the exposures of furcocercous prior to A. burminis. Prior infection with A. burminis induced negative effect on the host with an increased infection severity, while prior infection with furcocercous had reduced infection severity than lone exposures. These results suggest that furcocercous infections can be beneficial for hosts challenged with A. burminis provided that A. burminis exposure occurs second. None of the treatments had an effect on the growth of the tadpoles, but lengthening of developmental period was observed in some exposures. All exposed tadpoles developed malformations which were exclusively axial-kyphosis and scoliosis. However, there was no difference in the number of malformed individuals in the single infection (19.0%-25.0%) compared to coinfection (20.0%-22.5%) or between coinfections. The results suggest that the sequence of parasite exposure affects host-parasite interactions and hence the disease outcomes. Understanding the effects of coinfection on disease outcomes for hosts provides insight into disease dynamics.
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Affiliation(s)
- Nuwandi U. K. Pathirana
- Department of ZoologyUniversity of PeradeniyaPeradeniyaSri Lanka
- Postgraduate Institute of ScienceUniversity of PeradeniyaPeradeniyaSri Lanka
- Freshwater Fish Group and Fish Health Unit, Centre for Sustainable Aquatic Ecosystems, School of Veterinary & Life SciencesMurdoch UniversityPerthAustralia
| | - Madhava Meegaskumbura
- Guangxi Key Laboratory of Forest Ecology & Conservation, College of ForestryGuangxi UniversityNanningChina
- Department of Molecular Biology and Bio‐technologyUniversity of PeradeniyaPeradeniyaSri Lanka
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17
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Halliday FW, Umbanhowar J, Mitchell CE. A host immune hormone modifies parasite species interactions and epidemics: insights from a field manipulation. Proc Biol Sci 2018; 285:rspb.2018.2075. [PMID: 30404885 DOI: 10.1098/rspb.2018.2075] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 10/18/2018] [Indexed: 12/12/2022] Open
Abstract
Parasite epidemics can depend on priority effects, and parasite priority effects can result from the host immune response to prior infection. Yet we lack experimental evidence that such immune-mediated priority effects influence epidemics. To address this research gap, we manipulated key host immune hormones, then measured the consequences for within-host parasite interactions, and ultimately parasite epidemics in the field. Specifically, we applied plant immune-signalling hormones to sentinel plants, embedded into a wild host population, and tracked foliar infections caused by two common fungal parasites. Within-host individuals, priority effects were altered by the immune-signalling hormone, salicylic acid (SA). Scaling up from within-host interactions, hosts treated with SA experienced a lower prevalence of a less aggressive parasite, increased burden of infection by a more aggressive parasite, and experienced fewer co-infections. Together, these results indicate that by altering within-host priority effects, host immune hormones can drive parasite epidemics. This study therefore experimentally links host immune hormones to within-host priority effects and parasite epidemics, advancing a more mechanistic understanding of how interactions among parasites alter their epidemics.
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Affiliation(s)
- Fletcher W Halliday
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - James Umbanhowar
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA.,Curriculum for the Environment and Ecology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Charles E Mitchell
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA.,Curriculum for the Environment and Ecology, University of North Carolina, Chapel Hill, NC 27599, USA
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18
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Hochberg ME. An ecosystem framework for understanding and treating disease. EVOLUTION MEDICINE AND PUBLIC HEALTH 2018; 2018:270-286. [PMID: 30487969 PMCID: PMC6252061 DOI: 10.1093/emph/eoy032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 10/02/2018] [Indexed: 12/28/2022]
Abstract
Pathogens and cancers are pervasive health risks in the human population. I argue that if we are to better understand disease and its treatment, then we need to take an ecological perspective of disease itself. I generalize and extend an emerging framework that views disease as an ecosystem and many of its components as interacting in a community. I develop the framework for biological etiological agents (BEAs) that multiply within humans—focusing on bacterial pathogens and cancers—but the framework could be extended to include other host and parasite species. I begin by describing why we need an ecosystem framework to understand disease, and the main components and interactions in bacterial and cancer disease ecosystems. Focus is then given to the BEA and how it may proceed through characteristic states, including emergence, growth, spread and regression. The framework is then applied to therapeutic interventions. Central to success is preventing BEA evasion, the best known being antibiotic resistance and chemotherapeutic resistance in cancers. With risks of evasion in mind, I propose six measures that either introduce new components into the disease ecosystem or manipulate existing ones. An ecosystem framework promises to enhance our understanding of disease, BEA and host (co)evolution, and how we can improve therapeutic outcomes.
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Affiliation(s)
- Michael E Hochberg
- Institut des Sciences de l'Evolution, Université de Montpellier, 34095 Montpellier, France.,Santa Fe Institute, Santa Fe, NM 87501, USA.,Institute for Advanced Study in Toulouse, 31015 Toulouse, France
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19
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Vaccination can drive an increase in frequencies of antibiotic resistance among nonvaccine serotypes of Streptococcus pneumoniae. Proc Natl Acad Sci U S A 2018; 115:3102-3107. [PMID: 29511100 DOI: 10.1073/pnas.1718712115] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The bacterial pathogen Streptococcus pneumoniae is a major public health concern, being responsible for more than 1.5 million deaths annually through pneumonia, meningitis, and septicemia. Available vaccines target only a subset of serotypes, so vaccination is often accompanied by a rise in the frequency of nonvaccine serotypes. Epidemiological studies suggest that such a change in serotype frequencies is often coupled with an increase of antibiotic resistance among nonvaccine serotypes. Building on previous multilocus models for bacterial pathogen population structure, we have developed a theoretical framework incorporating variation of serotype and antibiotic resistance to examine how their associations may be affected by vaccination. Using this framework, we find that vaccination can result in a rapid increase in the frequency of preexisting resistant variants of nonvaccine serotypes due to the removal of competition from vaccine serotypes.
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20
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Wale N, Sim DG, Read AF. A nutrient mediates intraspecific competition between rodent malaria parasites in vivo. Proc Biol Sci 2018; 284:rspb.2017.1067. [PMID: 28747479 PMCID: PMC5543226 DOI: 10.1098/rspb.2017.1067] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 06/21/2017] [Indexed: 12/02/2022] Open
Abstract
Hosts are often infected with multiple strains of a single parasite species. Within-host competition between parasite strains can be intense and has implications for the evolution of traits that impact patient health, such as drug resistance and virulence. Yet the mechanistic basis of within-host competition is poorly understood. Here, we demonstrate that a parasite nutrient, para-aminobenzoic acid (pABA), mediates competition between a drug resistant and drug susceptible strain of the malaria parasite, Plasmodium chabaudi. We further show that increasing pABA supply to hosts infected with the resistant strain worsens disease and changes the relationship between parasite burden and pathology. Our experiments demonstrate that, even when there is profound top-down regulation (immunity), bottom-up regulation of pathogen populations can occur and that its importance may vary during an infection. The identification of resources that can be experimentally controlled opens up the opportunity to manipulate competitive interactions between parasites and hence their evolution.
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Affiliation(s)
- Nina Wale
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Derek G Sim
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Andrew F Read
- Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA.,Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA
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21
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Abdullah AS, Moffat CS, Lopez-Ruiz FJ, Gibberd MR, Hamblin J, Zerihun A. Host-Multi-Pathogen Warfare: Pathogen Interactions in Co-infected Plants. FRONTIERS IN PLANT SCIENCE 2017; 8:1806. [PMID: 29118773 PMCID: PMC5660990 DOI: 10.3389/fpls.2017.01806] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 10/04/2017] [Indexed: 05/04/2023]
Abstract
Studies of plant-pathogen interactions have historically focused on simple models of infection involving single host-single disease systems. However, plant infections often involve multiple species and/or genotypes and exhibit complexities not captured in single host-single disease systems. Here, we review recent insights into co-infection systems focusing on the dynamics of host-multi-pathogen interactions and the implications for host susceptibility/resistance. In co-infection systems, pathogen interactions include: (i) Competition, in which competing pathogens develop physical barriers or utilize toxins to exclude competitors from resource-dense niches; (ii) Cooperation, whereby pathogens beneficially interact, by providing mutual biochemical signals essential for pathogenesis, or through functional complementation via the exchange of resources necessary for survival; (iii) Coexistence, whereby pathogens can stably coexist through niche specialization. Furthermore, hosts are also able to, actively or passively, modulate niche competition through defense responses that target at least one pathogen. Typically, however, virulent pathogens subvert host defenses to facilitate infection, and responses elicited by one pathogen may be modified in the presence of another pathogen. Evidence also exists, albeit rare, of pathogens incorporating foreign genes that broaden niche adaptation and improve virulence. Throughout this review, we draw upon examples of co-infection systems from a range of pathogen types and identify outstanding questions for future innovation in disease control strategies.
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Affiliation(s)
- Araz S. Abdullah
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, WA, Australia
| | - Caroline S. Moffat
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, WA, Australia
| | - Francisco J. Lopez-Ruiz
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, WA, Australia
| | - Mark R. Gibberd
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, WA, Australia
| | - John Hamblin
- Institute of Agriculture, University of Western Australia, Perth, WA, Australia
| | - Ayalsew Zerihun
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, WA, Australia
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22
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Halliday FW, Umbanhowar J, Mitchell CE. Interactions among symbionts operate across scales to influence parasite epidemics. Ecol Lett 2017; 20:1285-1294. [DOI: 10.1111/ele.12825] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 07/23/2017] [Indexed: 12/31/2022]
Affiliation(s)
| | - James Umbanhowar
- Department of Biology University of North Carolina Chapel Hill NC27599 USA
- Curriculum for the Environment and Ecology University of North Carolina Chapel Hill NC27599 USA
| | - Charles E. Mitchell
- Department of Biology University of North Carolina Chapel Hill NC27599 USA
- Curriculum for the Environment and Ecology University of North Carolina Chapel Hill NC27599 USA
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23
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Mijele D, Iwaki T, Chiyo PI, Otiende M, Obanda V, Rossi L, Soriguer R, Angelone-Alasaad S. Influence of Massive and Long Distance Migration on Parasite Epidemiology: Lessons from the Great Wildebeest Migration. ECOHEALTH 2016; 13:708-719. [PMID: 27554373 DOI: 10.1007/s10393-016-1156-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 07/18/2016] [Accepted: 08/01/2016] [Indexed: 06/06/2023]
Abstract
Very little is known about the influence of massive and long distance migration on parasite epidemiology. Migration can simultaneously minimize exposure to common parasites in their habitats and increase exposure to novel pathogens from new environments and habitats encountered during migration, while physiological stress during long distance movement can lead to immune suppression, which makes migrants vulnerable to parasites. In this paper, we investigated the diversity, prevalence, parasite load, co-infection patterns and predilection sites of adult gastrointestinal helminths in 130 migrating wildebeests and tested for their relation with animal age, sex and migration time (which also could indicate different migration routes), and compared them with the non-migratory wildebeest. Surprisingly, only four parasite species were found, Oesophagostomum columbianum, Haemonchus placei, Calicophoron raja and Moniezia expansa, which were lower than in non-migratory wildebeest reported in the literature. These parasites were generalists, infecting livestock, and suggests that wildebeest and livestock, because of their interaction during migration, have a cross-infection risk. There was a negative relation between parasites diversity, prevalence and intensity of infection, and host age, which suggests that wildebeests acquire protective immunity against these parasites as they get older. Prevalence and intensity of infection were higher among wildebeest crossing the Mara Bridge (early migrants) compared to those crossing the Serena (late migrants), which suggests that early migrants (or migrants originating from different areas) have varying infection intensities. The prevalence and intensity of infection were higher in males compared to females and may be due to ecological, behavioural, or physiological differences between males and females. Our findings compared to those of previous studies suggest that migration may provide a mechanism to minimize exposure of hosts to common parasites through migratory escape, but this result awaits examination of helminths epidemiology of non-migratory wildebeests from areas of migrant origins. The potential parasitic cross-infection between wildebeests and livestock is a real risk to be taken into account in the management of wildebeest migration corridors.
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Affiliation(s)
- Domnic Mijele
- Forensic and Genetics Laboratory, Kenya Wildlife Service, P.O Box 40241-00100, Nairobi, Kenya.
| | - Takashi Iwaki
- Meguro Parasitological Museum, 4-1-1 Shimomeguro, Meguro-ku, Tokyo, 153-0064, Japan
| | - Patrick I Chiyo
- Forensic and Genetics Laboratory, Kenya Wildlife Service, P.O Box 40241-00100, Nairobi, Kenya
| | - Moses Otiende
- Forensic and Genetics Laboratory, Kenya Wildlife Service, P.O Box 40241-00100, Nairobi, Kenya
| | - Vincent Obanda
- Forensic and Genetics Laboratory, Kenya Wildlife Service, P.O Box 40241-00100, Nairobi, Kenya
| | - Luca Rossi
- Dipartimento di Scienze Veterinarie, Università degli Studi di Torino, L.go Braccini 1, I-10095, Grugliasco, Italy
| | - Ramon Soriguer
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Américo Vespucio s/n 41092, Seville, Spain
| | - Samer Angelone-Alasaad
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Américo Vespucio s/n 41092, Seville, Spain.
- Institute of Evolutionary Biology and Environmental Studies (IEU), University of Zürich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
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24
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Lewnard JA, Huppert A, Givon-Lavi N, Pettigrew MM, Regev-Yochay G, Dagan R, Weinberger DM. Density, Serotype Diversity, and Fitness of Streptococcus pneumoniae in Upper Respiratory Tract Cocolonization With Nontypeable Haemophilus influenzae. J Infect Dis 2016; 214:1411-1420. [PMID: 27540112 DOI: 10.1093/infdis/jiw381] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/10/2016] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Coinfections by Streptococcus pneumoniae and nontypeable Haemophilus influenzae (NTHi) are frequently implicated in complex otitis media. Whereas upper respiratory tract carriage precedes disease for both pathogens, interactions between species in cocolonized hosts are poorly understood. We compared colonization densities and the diversity and fitness of pneumococcal serotypes in single-species and mixed-species colonization. METHODS We analyzed nasopharyngeal pneumococcal carriage and nasopharyngeal and oropharyngeal NTHi carriage in 13 541 samples collected over 6909 study visits from 769 children 2-30 months old in a 7-valent pneumococcal conjugate vaccine dosing trial. We measured density associations between the species and compared pneumococcal serotype diversity during and in the absence of NTHi colonization. We used logistic regression to quantify associations between NTHi colonization and previously published pneumococcal serotype factors related to fitness. RESULTS Densities of the 2 species were positively associated when they co-occur in the nasopharynx. NTHi colonization was associated with reduced pneumococcal serotype diversity among children 2-18 months old and was more prevalent among children carrying pneumococcal serotypes with greater capsular thickness, neutrophil resistance, and metabolic efficiency. CONCLUSIONS Pneumococcal-NTHi cocolonization is associated with an elevated density of both species and with reduced diversity and increased fitness of pneumococcal serotypes. NTHi colonization may create a selective environment favoring pneumococci with immune-evasive phenotypes.
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Affiliation(s)
- Joseph A Lewnard
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut
| | | | - Noga Givon-Lavi
- Pediatric Infectious Disease Unit, Soroka University Medical Center.,Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Melinda M Pettigrew
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut
| | - Gili Regev-Yochay
- Section of Infectious Disease Epidemiology, Gertner Institute for Epidemiology and Health Policy Research.,Infectious Disease Unit, Sheba Medical Center, Ramat-Gan
| | - Ron Dagan
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Daniel M Weinberger
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut
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Parratt SR, Laine AL. The role of hyperparasitism in microbial pathogen ecology and evolution. THE ISME JOURNAL 2016; 10:1815-22. [PMID: 26784356 PMCID: PMC5029149 DOI: 10.1038/ismej.2015.247] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 10/19/2015] [Accepted: 11/25/2015] [Indexed: 11/09/2022]
Abstract
Many micro-organisms employ a parasitic lifestyle and, through their antagonistic interactions with host populations, have major impacts on human, agricultural and natural ecosystems. Most pathogens are likely to host parasites of their own, that is, hyperparasites, but how nested chains of parasites impact on disease dynamics is grossly neglected in the ecological and evolutionary literature. In this minireview we argue that the diversity and dynamics of micro-hyperparasites are an important component of natural host-pathogen systems. We use the current literature from a handful of key systems to show that observed patterns of pathogen virulence and disease dynamics may well be influenced by hyperparasites. Exploring these factors will shed light on many aspects of microbial ecology and disease biology, including resistance-virulence evolution, apparent competition, epidemiology and ecosystem stability. Considering the importance of hyperparasites in natural populations will have applied consequences for the field of biological control and therapeutic science, where hyperparastism is employed as a control mechanism but not necessarily ecologically understood.
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Affiliation(s)
- Steven R Parratt
- Department of Biosciences, Metapopulation Research Centre, University of Helsinki, Helsinki, Finland
| | - Anna-Liisa Laine
- Department of Biosciences, Metapopulation Research Centre, University of Helsinki, Helsinki, Finland
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Stockmann C, Ampofo K, Pavia AT, Blaschke AJ, Mason EO, Presson AP, Forney LJ, Byington CL. Clinical and Epidemiological Evidence of the Red Queen Hypothesis in Pneumococcal Serotype Dynamics. Clin Infect Dis 2016; 63:619-626. [PMID: 27282711 DOI: 10.1093/cid/ciw357] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 05/20/2016] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND The Red Queen hypothesis is an evolutionary theory that describes the reciprocal coevolution of competing species. We sought to study whether introduction of the 7- and 13-valent pneumococcal conjugate vaccines (PCV7 and PCV13, respectively) altered pneumococcal serotype dynamics among children with invasive pneumococcal disease (IPD) as predicted by the Red Queen hypothesis. METHODS This study examined pneumococcal isolates (n = 641) obtained from children <18 years of age hospitalized with IPD from 1997 to 2014 in Utah. A review of the literature also identified several additional studies conducted in the United States and Europe that were used to test the external generalizability of our Utah findings. Simpson's index was used to quantify pneumococcal serotype diversity. RESULTS In Utah, the introduction of PCV7 and PCV13 was associated with rapid increases in serotype diversity (P < .001). Serotypes rarely present before vaccine introduction emerged as common causes of IPD. Diversity then decreased (P < .001) as competition selected for the fittest serotypes and new evolutionary equilibriums were established. This pattern was also observed more broadly in the United States, the United Kingdom, Norway, and Spain. CONCLUSIONS This vaccine-driven example of human/bacterial coevolution appears to confirm the Red Queen hypothesis, which reveals a limitation of serotype-specific vaccines and offers insights that may facilitate alternative strategies for the elimination of IPD.
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Affiliation(s)
- Chris Stockmann
- Department of Pediatrics, University of Utah, Salt Lake City
| | - Krow Ampofo
- Department of Pediatrics, University of Utah, Salt Lake City
| | - Andrew T Pavia
- Department of Pediatrics, University of Utah, Salt Lake City
| | - Anne J Blaschke
- Department of Pediatrics, University of Utah, Salt Lake City
| | | | - Angela P Presson
- Study Design and Biostatistics Center, University of Utah, Salt Lake City
| | - Larry J Forney
- Department of Biological Sciences, University of Idaho, Moscow
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Mordecai EA, Gross K, Mitchell CE. Within-Host Niche Differences and Fitness Trade-offs Promote Coexistence of Plant Viruses. Am Nat 2016; 187:E13-26. [DOI: 10.1086/684114] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Blaisdell GK, Zhang S, Bratburd JR, Daane KM, Cooper ML, Almeida RPP. Interactions Within Susceptible Hosts Drive Establishment of Genetically Distinct Variants of an Insect-Borne Pathogen. JOURNAL OF ECONOMIC ENTOMOLOGY 2015; 108:1531-1539. [PMID: 26470292 DOI: 10.1093/jee/tov153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 05/15/2015] [Indexed: 06/05/2023]
Abstract
Coinfections are common, leading to pathogen interactions during transmission and establishment in a host. However, few studies have tested the relative strengths of pathogen interactions in vectors and hosts that determine the outcome of infection. We tested interactions between two genetically distinct variants of the mealybug-transmitted Grapevine leafroll-associated virus 3. The transmission efficiency of each variant in single variant inoculations by two vector species was determined. The effects of vector species, a coinfected source, and simultaneous inoculation from multiple hosts to one host on variant establishment were examined. Within-vector interactions could have a role in transmission from hosts containing mixed infections, but not when vectors were moved from separate singly infected source plants to a single recipient plant. The invasive Planococcus ficus (Signoret) was a more efficient vector than Pseudococcus viburni (Signoret). Transmission efficiency of the two variants did not differ in single variant inoculations. Overall infections were the same whether from singly or coinfected source plants. In mixed inoculations, establishment of one variant was reduced. Mixed inoculations from two singly infected source plants resulted in fewer mixed infections than expected by chance. Therefore, the observed outcome was determined subsequent to host inoculation rather than in the vector. The outcome may be due to resource competition between pathogens. Alternatively apparent competition may be responsible; the pathogens' differential ability to overcome host defenses and colonize the host may determine the final outcome of new infections. Detailed knowledge of interactions between pathogens during transmission and establishment could improve understanding and management of disease spread.
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Affiliation(s)
- G K Blaisdell
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720
| | - S Zhang
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720
| | - J R Bratburd
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720
| | - K M Daane
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720
| | - M L Cooper
- Division of Agriculture and Natural Resources, University of California, UC Cooperative Extension, 1710 Soscol Ave., Suite 4, Napa, CA 94559
| | - R P P Almeida
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720.
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Rynkiewicz EC, Pedersen AB, Fenton A. An ecosystem approach to understanding and managing within-host parasite community dynamics. Trends Parasitol 2015; 31:212-21. [PMID: 25814004 DOI: 10.1016/j.pt.2015.02.005] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 02/24/2015] [Accepted: 02/24/2015] [Indexed: 10/23/2022]
Abstract
Hosts are typically coinfected by multiple parasite species, resulting in potentially overwhelming levels of complexity. We argue that an individual host can be considered to be an ecosystem in that it is an environment containing a diversity of entities (e.g., parasitic organisms, commensal symbionts, host immune components) that interact with each other, potentially competing for space, energy, and resources, ultimately influencing the condition of the host. Tools and concepts from ecosystem ecology can be applied to better understand the dynamics and responses of within-individual host-parasite ecosystems. Examples from both wildlife and human systems demonstrate how this framework is useful in breaking down complex interactions into components that can be monitored, measured, and managed to inform the design of better disease-management strategies.
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Affiliation(s)
- Evelyn C Rynkiewicz
- Institute of Evolutionary Biology, and Centre for Immunity, Infection and Evolution, Kings Buildings, Ashworth Laboratories, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK.
| | - Amy B Pedersen
- Institute of Evolutionary Biology, and Centre for Immunity, Infection and Evolution, Kings Buildings, Ashworth Laboratories, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Andy Fenton
- Institute of Integrative Biology, Biosciences Building, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
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Heesterbeek H, Anderson RM, Andreasen V, Bansal S, De Angelis D, Dye C, Eames KTD, Edmunds WJ, Frost SDW, Funk S, Hollingsworth TD, House T, Isham V, Klepac P, Lessler J, Lloyd-Smith JO, Metcalf CJE, Mollison D, Pellis L, Pulliam JRC, Roberts MG, Viboud C. Modeling infectious disease dynamics in the complex landscape of global health. Science 2015; 347:aaa4339. [PMID: 25766240 PMCID: PMC4445966 DOI: 10.1126/science.aaa4339] [Citation(s) in RCA: 346] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Despite some notable successes in the control of infectious diseases, transmissible pathogens still pose an enormous threat to human and animal health. The ecological and evolutionary dynamics of infections play out on a wide range of interconnected temporal, organizational, and spatial scales, which span hours to months, cells to ecosystems, and local to global spread. Moreover, some pathogens are directly transmitted between individuals of a single species, whereas others circulate among multiple hosts, need arthropod vectors, or can survive in environmental reservoirs. Many factors, including increasing antimicrobial resistance, increased human connectivity and changeable human behavior, elevate prevention and control from matters of national policy to international challenge. In the face of this complexity, mathematical models offer valuable tools for synthesizing information to understand epidemiological patterns, and for developing quantitative evidence for decision-making in global health.
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Affiliation(s)
- Hans Heesterbeek
- Faculty of Veterinary Medicine, University of Utrecht, Utrecht, Netherlands.
| | | | | | | | | | | | - Ken T D Eames
- Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene Tropical Medicine, London, UK
| | - W John Edmunds
- Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene Tropical Medicine, London, UK
| | | | | | - T Deirdre Hollingsworth
- School of Life Sciences, University of Warwick, UK. School of Tropical Medicine, University of Liverpool, UK
| | - Thomas House
- Warwick Mathematics Institute, University of Warwick, Coventry, UK
| | - Valerie Isham
- Department of Statistical Science, University College London, London, UK
| | | | - Justin Lessler
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - James O Lloyd-Smith
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
| | - C Jessica E Metcalf
- Department of Zoology, University of Oxford, Oxford, UK, and Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | | | - Lorenzo Pellis
- Warwick Mathematics Institute, University of Warwick, Coventry, UK
| | - Juliet R C Pulliam
- Department of Biology-Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA. Division of International Epidemiology and Population Studies, Fogarty International Center, NIH, Bethesda, MD, USA
| | - Mick G Roberts
- Institute of Natural and Mathematical Sciences, Massey University, Auckland, New Zealand
| | - Cecile Viboud
- Division of International Epidemiology and Population Studies, Fogarty International Center, NIH, Bethesda, MD, USA
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31
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Abstract
Host immunity is a major driver of pathogen evolution and thus a major determinant of pathogen diversity. Explanations for pathogen diversity traditionally assume simple interactions between pathogens and the immune system, a view encapsulated by the susceptible-infected-recovered (SIR) model. However, there is growing evidence that the complexity of many host-pathogen interactions is dynamically important. This revised perspective requires broadening the definition of a pathogen's immunological phenotype, or what can be thought of as its immunological niche. After reviewing evidence that interactions between pathogens and host immunity drive much of pathogen evolution, I introduce the concept of a pathogen's immunological phenotype. Models that depart from the SIR paradigm demonstrate the utility of this perspective and show that it is particularly useful in understanding vaccine-induced evolution. This paper highlights questions in immunology, evolution, and ecology that must be answered to advance theories of pathogen diversity.
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Affiliation(s)
- Sarah Cobey
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois
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Biesbroek G, Wang X, Keijser BJF, Eijkemans RMJ, Trzciński K, Rots NY, Veenhoven RH, Sanders EAM, Bogaert D. Seven-valent pneumococcal conjugate vaccine and nasopharyngeal microbiota in healthy children. Emerg Infect Dis 2014; 20:201-10. [PMID: 24447437 PMCID: PMC3901477 DOI: 10.3201/eid2002.131220] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Careful monitoring of vaccines against common bacterial colonizers is needed. Seven-valent pneumococcal conjugate vaccine (PCV-7) is effective against vaccine serotype disease and carriage. Nevertheless, shifts in colonization and disease toward nonvaccine serotypes and other potential pathogens have been described. To understand the extent of these shifts, we analyzed nasopharyngeal microbial profiles of 97 PCV-7–vaccinated infants and 103 control infants participating in a randomized controlled trial in the Netherlands. PCV-7 immunization resulted in a temporary shift in microbial community composition and increased bacterial diversity. Immunization also resulted in decreased presence of the pneumococcal vaccine serotype and an increase in the relative abundance and presence of nonpneumococcal streptococci and anaerobic bacteria. Furthermore, the abundance of Haemophilus and Staphylococcus bacteria in vaccinees was increased over that in controls. This study illustrates the much broader effect of vaccination with PCV-7 on the microbial community than currently assumed, and highlights the need for careful monitoring when implementing vaccines directed against common colonizers.
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Host and parasite diversity jointly control disease risk in complex communities. Proc Natl Acad Sci U S A 2013; 110:16916-21. [PMID: 24082092 DOI: 10.1073/pnas.1310557110] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Host-parasite interactions are embedded within complex communities composed of multiple host species and a cryptic assemblage of other parasites. To date, however, surprisingly few studies have explored the joint effects of host and parasite richness on disease risk, despite growing interest in the diversity-disease relationship. Here, we combined field surveys and mechanistic experiments to test how transmission of the virulent trematode Ribeiroia ondatrae was affected by the diversity of both amphibian hosts and coinfecting parasites. Within natural wetlands, host and parasite species richness correlated positively, consistent with theoretical predictions. Among sites that supported Ribeiroia, however, host and parasite richness interacted to negatively affect Ribeiroia transmission between its snail and amphibian hosts, particularly in species-poor assemblages. In laboratory and outdoor experiments designed to decouple the relative contributions of host and parasite diversity, increases in host richness decreased Ribeiroia infection by 11-65%. Host richness also tended to decrease total infections by other parasite species (four of six instances), such that more diverse host assemblages exhibited ∼40% fewer infections overall. Importantly, parasite richness further reduced both per capita and total Ribeiroia infection by 15-20%, possibly owing to intrahost competition among coinfecting species. These findings provide evidence that parasitic and free-living diversity jointly regulate disease risk, help to resolve apparent contradictions in the diversity-disease relationship, and emphasize the challenges of integrating research on coinfection and host heterogeneity to develop a community ecology-based approach to infectious diseases.
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34
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Hoverman JT, Hoye BJ, Johnson PTJ. Does timing matter? How priority effects influence the outcome of parasite interactions within hosts. Oecologia 2013; 173:1471-80. [DOI: 10.1007/s00442-013-2692-x] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 05/16/2013] [Indexed: 11/29/2022]
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35
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Dunne EM, Smith-Vaughan HC, Robins-Browne RM, Mulholland EK, Satzke C. Nasopharyngeal microbial interactions in the era of pneumococcal conjugate vaccination. Vaccine 2013; 31:2333-42. [PMID: 23523773 DOI: 10.1016/j.vaccine.2013.03.024] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 02/27/2013] [Accepted: 03/12/2013] [Indexed: 02/07/2023]
Abstract
The nasopharynx of children is often colonised by microorganisms such as Streptococcus pneumoniae (the pneumococcus) that can cause infections including pneumonia and otitis media. In this complex environment, bacteria and viruses may impact each other through antagonistic as well as synergistic interactions. Vaccination may alter colonisation dynamics, evidenced by the rise in non-vaccine serotypes following pneumococcal conjugate vaccination. Discovery of an inverse relationship between S. pneumoniae and Staphylococcus aureus carriage generated concern that pneumococcal vaccination could increase S. aureus carriage and disease. Here we review data on co-colonisation of pathogens in the nasopharynx, focusing on S. pneumoniae and the impact of pneumococcal vaccination. Thus far, pneumococcal vaccination has not had a sustained impact on S. aureus carriage but it is associated with an increase in non-typeable Haemophilus influenzae in acute otitis media aetiology. Advances in bacterial and viral detection methodologies have facilitated research in nasopharyngeal microbiology and will aid investigation of potential vaccine-induced changes, particularly when baseline studies can be conducted prior to pneumococcal vaccine introduction.
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Affiliation(s)
- Eileen M Dunne
- Pneumococcal Research, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, VIC, Australia.
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