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Backus L, Foley P, Foley J. A compartment and metapopulation model of Rocky Mountain spotted fever in southwestern United States and northern Mexico. Infect Dis Model 2024; 9:713-727. [PMID: 38659493 PMCID: PMC11039326 DOI: 10.1016/j.idm.2024.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/25/2024] [Accepted: 04/12/2024] [Indexed: 04/26/2024] Open
Abstract
Rocky Mountain spotted fever (RMSF) is a fatal tick-borne zoonotic disease that has emerged as an epidemic in western North America since the turn of the 21st century. Along the US south-western border and across northern Mexico, the brown dog tick, Rhipicephalus sanguineus, is responsible for spreading the disease between dogs and humans. The widespread nature of the disease and the ongoing epidemics contrast with historically sporadic patterns of the disease. Because dogs are amplifying hosts for the Rickettsia rickettsii bacteria, transmission dynamics between dogs and ticks are critical for understanding the epidemic. In this paper, we developed a compartment metapopulation model and used it to explore the dynamics and drivers of RMSF in dogs and brown dog ticks in a theoretical region in western North America. We discovered that there is an extended lag-as much as two years-between introduction of the pathogen to a naïve population and epidemic-level transmission, suggesting that infected ticks could disseminate extensively before disease is detected. A single large city-size population of dogs was sufficient to maintain the disease over a decade and serve as a source for disease in surrounding smaller towns. This model is a novel tool that can be used to identify high risk areas and key intervention points for epidemic RMSF spread by brown dog ticks.
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Affiliation(s)
- Laura Backus
- School of Veterinary Medicine, Department of Medicine and Epidemiology, University of California, Davis, CA, USA
| | - Patrick Foley
- Department of Biological Sciences, California State University, Sacramento, CA, USA
| | - Janet Foley
- School of Veterinary Medicine, Department of Medicine and Epidemiology, University of California, Davis, CA, USA
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Helikumi M, Lolika PO, Mushayabasa S. Implications of seasonal variations, host and vector migration on spatial spread of sleeping sickness: Insights from a mathematical model. INFORMATICS IN MEDICINE UNLOCKED 2021. [DOI: 10.1016/j.imu.2021.100570] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
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3
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Holding M, Dowall SD, Medlock JM, Carter DP, Pullan ST, Lewis J, Vipond R, Rocchi MS, Baylis M, Hewson R. Tick-Borne Encephalitis Virus, United Kingdom. Emerg Infect Dis 2020; 26:90-96. [PMID: 31661056 PMCID: PMC6924911 DOI: 10.3201/eid2601.191085] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
During February 2018–January 2019, we conducted large-scale surveillance for the presence and prevalence of tick-borne encephalitis virus (TBEV) and louping ill virus (LIV) in sentinel animals and ticks in the United Kingdom. Serum was collected from 1,309 deer culled across England and Scotland. Overall, 4% of samples were ELISA-positive for the TBEV serocomplex. A focus in the Thetford Forest area had the highest proportion (47.7%) of seropositive samples. Ticks collected from culled deer within seropositive regions were tested for viral RNA; 5 of 2,041 ticks tested positive by LIV/TBEV real-time reverse transcription PCR, all from within the Thetford Forest area. From 1 tick, we identified a full-length genomic sequence of TBEV. Thus, using deer as sentinels revealed a potential TBEV focus in the United Kingdom. This detection of TBEV genomic sequence in UK ticks has important public health implications, especially for undiagnosed encephalitis.
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Forest Connectivity, Host Assemblage Characteristics of Local and Neighboring Counties, and Temperature Jointly Shape the Spatial Expansion of Lyme Disease in United States. REMOTE SENSING 2019. [DOI: 10.3390/rs11202354] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Understanding risk factors for the spread of infectious diseases over time and across the landscape is critical for managing disease risk. While habitat connectivity and characteristics of local and neighboring animal (i.e., host) assemblages are known to influence the spread of diseases, the interactions among these factors remain poorly understood. In this study, we conducted a county-level analysis to test the effects of forest connectivity, together with the suitability of local assemblage (measured by the similarity of local host assemblage with neighboring assemblages) and the infection intensity of neighboring counties on the spatial expansion of Lyme disease in the United States. Our results suggested that both the similarity of local host assemblage and the infection intensity of neighboring counties were positively correlated with the probability of disease spread. Moreover, we found that increasing forest connectivity could facilitate the positive effect of neighbor infection intensity. In contrast, the effect size of the host assemblage similarity decreased with increasing connectivity, suggesting that host assemblage similarity was less effective in well-connected habitats. Our results thus indicate that habitat connectivity can indirectly influence disease spread by mediating the effects of other risk factors.
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The effects of climate change on avian migratory patterns and the dispersal of commercial poultry diseases in Canada - Part II. WORLD POULTRY SCI J 2019. [DOI: 10.1017/s0043933913000147] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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6
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Esser HJ, Mögling R, Cleton NB, van der Jeugd H, Sprong H, Stroo A, Koopmans MPG, de Boer WF, Reusken CBEM. Risk factors associated with sustained circulation of six zoonotic arboviruses: a systematic review for selection of surveillance sites in non-endemic areas. Parasit Vectors 2019; 12:265. [PMID: 31133059 PMCID: PMC6537422 DOI: 10.1186/s13071-019-3515-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 05/19/2019] [Indexed: 12/30/2022] Open
Abstract
Arboviruses represent a significant burden to public health and local economies due to their ability to cause unpredictable and widespread epidemics. To maximize early detection of arbovirus emergence in non-endemic areas, surveillance efforts should target areas where circulation is most likely. However, identifying such hotspots of potential emergence is a major challenge. The ecological conditions leading to arbovirus outbreaks are shaped by complex interactions between the virus, its vertebrate hosts, arthropod vector, and abiotic environment that are often poorly understood. Here, we systematically review the ecological risk factors associated with the circulation of six arboviruses that are of considerable concern to northwestern Europe. These include three mosquito-borne viruses (Japanese encephalitis virus, West Nile virus, Rift Valley fever virus) and three tick-borne viruses (Crimean-Congo hemorrhagic fever virus, tick-borne encephalitis virus, and louping-ill virus). We consider both intrinsic (e.g. vector and reservoir host competence) and extrinsic (e.g. temperature, precipitation, host densities, land use) risk factors, identify current knowledge gaps, and discuss future directions. Our systematic review provides baseline information for the identification of regions and habitats that have suitable ecological conditions for endemic circulation, and therefore may be used to target early warning surveillance programs aimed at detecting multi-virus and/or arbovirus emergence.
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Affiliation(s)
- Helen J Esser
- Resource Ecology Group, Wageningen University & Research, Wageningen, The Netherlands. .,Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands.
| | - Ramona Mögling
- Department of Viroscience, WHO CC for arbovirus and viral hemorrhagic fever reference and research, Erasmus University Medical Centre, Rotterdam, The Netherlands
| | - Natalie B Cleton
- Department of Viroscience, WHO CC for arbovirus and viral hemorrhagic fever reference and research, Erasmus University Medical Centre, Rotterdam, The Netherlands.,Centre for Infectious Disease Control, National Institute for Public Health and Environment (RIVM), Bilthoven, The Netherlands
| | - Henk van der Jeugd
- Vogeltrekstation-Dutch Centre for Avian Migration and Demography, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Hein Sprong
- Centre for Infectious Disease Control, National Institute for Public Health and Environment (RIVM), Bilthoven, The Netherlands
| | - Arjan Stroo
- Centre for Monitoring of Vectors (CMV), National Reference Centre (NRC), Netherlands Food and Consumer Product Safety Authority (NVWA), Ministry of Economic Affairs, Wageningen, The Netherlands
| | - Marion P G Koopmans
- Department of Viroscience, WHO CC for arbovirus and viral hemorrhagic fever reference and research, Erasmus University Medical Centre, Rotterdam, The Netherlands
| | - Willem F de Boer
- Resource Ecology Group, Wageningen University & Research, Wageningen, The Netherlands
| | - Chantal B E M Reusken
- Department of Viroscience, WHO CC for arbovirus and viral hemorrhagic fever reference and research, Erasmus University Medical Centre, Rotterdam, The Netherlands.,Centre for Infectious Disease Control, National Institute for Public Health and Environment (RIVM), Bilthoven, The Netherlands
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Abstract
SUMMARYTicks are vectors of pathogens which are important both with respect to human health and economically. They have a complex life cycle requiring several blood meals throughout their life. These blood meals take place on different individual hosts and potentially on different host species. Their life cycle is also dependent on environmental conditions such as the temperature and habitat type. Mathematical models have been used for the more than 30 years to help us understand how tick dynamics are dependent on these environmental factors and host availability. In this paper, we review models of tick dynamics and summarize the main results. This summary is split into two parts, one which looks at tick dynamics and one which looks at tick-borne pathogens. In general, the models of tick dynamics are used to determine when the peak in tick densities is likely to occur in the year and how that changes with environmental conditions. The models of tick-borne pathogens focus more on the conditions under which the pathogen can persist and how host population densities might be manipulated to control these pathogens. In the final section of the paper, we identify gaps in the current knowledge and future modelling approaches. These include spatial models linked to environmental information and Geographic Information System maps, and development of new modelling techniques which model tick densities per host more explicitly.
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Impacts of deer management practices on the spatial dynamics of the tick Ixodes ricinus: A scenario analysis. Ecol Modell 2014. [DOI: 10.1016/j.ecolmodel.2013.12.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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9
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Kraft JP, Stapp P. Movements and burrow use by northern grasshopper mice as a possible mechanism of plague spread in prairie dog colonies. J Mammal 2013. [DOI: 10.1644/12-mamm-a-197.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Li S, Heyman P, Cochez C, Simons L, Vanwambeke SO. A multi-level analysis of the relationship between environmental factors and questing Ixodes ricinus dynamics in Belgium. Parasit Vectors 2012; 5:149. [PMID: 22830528 PMCID: PMC3419667 DOI: 10.1186/1756-3305-5-149] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 07/09/2012] [Indexed: 11/10/2022] Open
Abstract
Background Ticks are the most important pathogen vectors in Europe. They are known to be influenced by environmental factors, but these links are usually studied at specific temporal or spatial scales. Focusing on Ixodes ricinus in Belgium, we attempt to bridge the gap between current “single-sided” studies that focus on temporal or spatial variation only. Here, spatial and temporal patterns of ticks are modelled together. Methods A multi-level analysis of the Ixodes ricinus patterns in Belgium was performed. Joint effects of weather, habitat quality and hunting on field sampled tick abundance were examined at two levels, namely, sampling level, which is associated with temporal dynamics, and site level, which is related to spatial dynamics. Independent variables were collected from standard weather station records, game management data and remote sensing-based land cover data. Results At sampling level, only a marginally significant effect of daily relative humidity and temperature on the abundance of questing nymphs was identified. Average wind speed of seven days prior to the sampling day was found important to both questing nymphs and adults. At site level, a group of landscape-level forest fragmentation indices were highlighted for both questing nymph and adult abundance, including the nearest-neighbour distance, the shape and the aggregation level of forest patches. No cross-level effects or spatial autocorrelation were found. Conclusions Nymphal and adult ticks responded differently to environmental variables at different spatial and temporal scales. Our results can advise spatio-temporal extents of environment data collection for continuing empirical investigations and potential parameters for biological tick models.
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Affiliation(s)
- Sen Li
- Georges Lemaître Centre for Earth and Climate Research, Earth and Life Institute, Université catholique de Louvain, B-1348, Louvain-la-Neuve, Belgium.
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Li S, Hartemink N, Speybroeck N, Vanwambeke SO. Consequences of landscape fragmentation on Lyme disease risk: a cellular automata approach. PLoS One 2012; 7:e39612. [PMID: 22761842 PMCID: PMC3382467 DOI: 10.1371/journal.pone.0039612] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 05/23/2012] [Indexed: 11/19/2022] Open
Abstract
The abundance of infected Ixodid ticks is an important component of human risk of Lyme disease, and various empirical studies have shown that this is associated, at least in part, to landscape fragmentation. In this study, we aimed at exploring how varying woodland fragmentation patterns affect the risk of Lyme disease, through infected tick abundance. A cellular automata model was developed, incorporating a heterogeneous landscape with three interactive components: an age-structured tick population, a classical disease transmission function, and hosts. A set of simplifying assumptions were adopted with respect to the study objective and field data limitations. In the model, the landscape influences both tick survival and host movement. The validation of the model was performed with an empirical study. Scenarios of various landscape configurations (focusing on woodland fragmentation) were simulated and compared. Lyme disease risk indices (density and infection prevalence of nymphs) differed considerably between scenarios: (i) the risk could be higher in highly fragmented woodlands, which is supported by a number of recently published empirical studies, and (ii) grassland could reduce the risk in adjacent woodland, which suggests landscape fragmentation studies of zoonotic diseases should not focus on the patch-level woodland patterns only, but also on landscape-level adjacent land cover patterns. Further analysis of the simulation results indicated strong correlations between Lyme disease risk indices and the density, shape and aggregation level of woodland patches. These findings highlight the strong effect of the spatial patterns of local host population and movement on the spatial dynamics of Lyme disease risks, which can be shaped by woodland fragmentation. In conclusion, using a cellular automata approach is beneficial for modelling complex zoonotic transmission systems as it can be combined with either real world landscapes for exploring direct spatial effects or artificial representations for outlining possible empirical investigations.
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Affiliation(s)
- Sen Li
- Georges Lemaître Centre for Earth and Climate Research, Earth and Life Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
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ALLEN LJS, BROWN VL, JONSSON CB, KLEIN SL, LAVERTY SM, MAGWEDERE K, OWEN JC, VAN DEN DRIESSCHE P. Mathematical Modeling of Viral Zoonoses in Wildlife. NATURAL RESOURCE MODELING 2012; 25:5-51. [PMID: 22639490 PMCID: PMC3358807 DOI: 10.1111/j.1939-7445.2011.00104.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Zoonoses are a worldwide public health concern, accounting for approximately 75% of human infectious diseases. In addition, zoonoses adversely affect agricultural production and wildlife. We review some mathematical models developed for the study of viral zoonoses in wildlife and identify areas where further modeling efforts are needed.
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Affiliation(s)
- L. J. S. ALLEN
- Department of Mathematics and Statistics, Texas Tech University, Lubbock, TX 79409, E‐mail:
| | - V. L. BROWN
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109
| | - C. B. JONSSON
- Center for Predictive Medicine for Biodefense and Emerging Infectious Disease, University of Louisville, Louisville, KY 40202
| | - S. L. KLEIN
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205
| | - S. M. LAVERTY
- Department of Mathematics, University of Utah, Salt Lake City, UT 84112
| | - K. MAGWEDERE
- Division of Veterinary Public Health, Directorate of Veterinary Services, Mariental, Namibia, Africa
| | - J. C. OWEN
- Departments of Fisheries and Wildlife and Large Animal Clinical Sciences, Michigan State University, East Lansing, MI 48824
| | - P. VAN DEN DRIESSCHE
- Department of Mathematics and Statistics, University of Victoria, Victoria, BC, Canada V8W 3R4
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Fenner AL, Godfrey SS, Michael Bull C. Using social networks to deduce whether residents or dispersers spread parasites in a lizard population. J Anim Ecol 2011; 80:835-43. [PMID: 21644975 DOI: 10.1111/j.1365-2656.2011.01825.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. Heterogeneity of host behaviour can play an important role in the spread of parasites and pathogens around wildlife populations. Social networks have previously been suggested to represent transmission pathways within a population, but where the dynamics of host-parasite interactions are difficult to observe, networks may also be used to provide insights into transmission processes. 2. Pygmy bluetongue lizards, Tiliqua adelaidensis, occupy individual territories, live exclusively in burrows constructed by spiders in Australian native grasslands and are hosts to a tick, Bothriocroton hydrosauri, and a nematode, Pharyngodon wandillahensis. 3. On five monthly occasions, the locations of all individual lizards in three study plots were used to construct weighted, undirected networks based on proximity of adjacent burrows. 4. The networks were used to explore alternative hypotheses about the spread of each parasite through the population: that stable population members that remained in the same burrow over the study period played a major role in influencing the pattern of infection or that dispersing individuals played a more significant role. 5. For ticks, host individuals that were infected were more connected in the network than uninfected hosts and this relationship remained significant for connections to residents in the population, but not for connections to dispersers. 6. For nematodes, infected and uninfected hosts did not differ in their overall strength of connection in the network, but infected hosts were more connected to dispersers than were uninfected hosts, suggesting that lizards moving across the population are the major agents for the transmission of nematodes. 7. This study shows how network analyses can provide new insights into alternative pathways of parasite spread in wildlife populations, where it is difficult to make direct observations of transmission-related behaviours.
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Affiliation(s)
- Aaron L Fenner
- School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide 5001, South Australia, Australia
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Hancock PA, Brackley R, Palmer SCF. Modelling the effect of temperature variation on the seasonal dynamics of Ixodes ricinus tick populations. Int J Parasitol 2011; 41:513-22. [PMID: 21295037 DOI: 10.1016/j.ijpara.2010.12.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Revised: 12/03/2010] [Accepted: 12/05/2010] [Indexed: 11/18/2022]
Abstract
Seasonal variation in temperature is known to drive annual patterns of tick activity and can influence the dynamics of tick-borne diseases. An age-structured model of the dynamics of Ixodes ricinus populations was developed to explore how changes in average temperature and different levels of temperature variability affect seasonal patterns of tick activity and the transmission of tick-borne diseases. The model produced seasonal patterns of tick emergence that are consistent with those observed throughout Great Britain. Varying average temperature across a continuous spectrum produced a systematic pattern in the times of peak emergence of questing ticks which depends on cumulative temperature over the year. Examination of the effects of between-year stochastic temperature variation on this pattern indicated that peak emergence times are more strongly affected by temperature stochasticity at certain levels of average temperature. Finally the model was extended to give a simple representation of the dynamics of a tick-borne disease. A threshold level of annual cumulative temperature was identified at which disease persistence is sensitive to stochastic temperature variation. In conclusion, the effect of changing patterns of temperature variation on the dynamics of I. ricinus ticks and the diseases they transmit may depend on the cumulative temperature over the year and will therefore vary across different locations. The results also indicate that diapause mechanisms have an important influence on seasonal patterns of tick activity and require further study.
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Affiliation(s)
- Penelope A Hancock
- Centre for Population Biology, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK.
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Controlling tick-borne diseases through domestic animal management: a theoretical approach. THEOR ECOL-NETH 2010. [DOI: 10.1007/s12080-010-0080-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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