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  • 1.
    Brännström, Åke
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Advancing Systems Analysis Program, International Institute for Applied Systems Analysis, Laxenburg, Austria.
    Sjödin, Henrik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Rocklöv, Joacim
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    A Method for Estimating the Number of Infections From the Reported Number of Deaths2022Ingår i: Frontiers In Public Health, ISSN 2296-2565, Vol. 9, artikel-id 648545Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    At the outset of an epidemic, available case data typically underestimate the total number of infections due to insufficient testing, potentially hampering public responses. Here, we present a method for statistically estimating the true number of cases with confidence intervals from the reported number of deaths and estimates of the infection fatality ratio; assuming that the time from infection to death follows a known distribution. While the method is applicable to any epidemic with a significant mortality rate, we exemplify the method by applying it to COVID-19. Our findings indicate that the number of unreported COVID-19 infections in March 2020 was likely to be at least one order of magnitude higher than the reported cases, with the degree of underestimation among the countries considered being particularly high in the United Kingdom.

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  • 2. Colon-Gonzalez, J. Felipe
    et al.
    Sewe, Maquins Odhiambo
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Tompkins, M. Adrian
    Sjödin, Henrik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Casallas, Alejandro
    Rocklöv, Joacim
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa. Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany.
    Caminade, Cyril
    Lowe, Rachel
    Projecting the risk of mosquito-borne diseases in a warmer and more populated world: a multi-model, multi-scenario intercomparison modelling study2021Ingår i: The Lancet Planetary Health, E-ISSN 2542-5196, Vol. 5, nr 7, s. E404-E414Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Mosquito-borne diseases are expanding their range, and re-emerging in areas where they had subsided for decades. The extent to which climate change influences the transmission suitability and population at risk of mosquito-borne diseases across different altitudes and population densities has not been investigated. The aim of this study was to quantify the extent to which climate change will influence the length of the transmission season and estimate the population at risk of mosquito-borne diseases in the future, given different population densities across an altitudinal gradient.

    Methods: Using a multi-model multi-scenario framework, we estimated changes in the length of the transmission season and global population at risk of malaria and dengue for different altitudes and population densities for the period 1951-99. We generated projections from six mosquito-borne disease models, driven by four global circulation models, using four representative concentration pathways, and three shared socioeconomic pathways.

    Findings: We show that malaria suitability will increase by 1·6 additional months (mean 0·5, SE 0·03) in tropical highlands in the African region, the Eastern Mediterranean region, and the region of the Americas. Dengue suitability will increase in lowlands in the Western Pacific region and the Eastern Mediterranean region by 4·0 additional months (mean 1·7, SE 0·2). Increases in the climatic suitability of both diseases will be greater in rural areas than in urban areas. The epidemic belt for both diseases will expand towards temperate areas. The population at risk of both diseases might increase by up to 4·7 additional billion people by 2070 relative to 1970-99, particularly in lowlands and urban areas.

    Interpretation: Rising global mean temperature will increase the climatic suitability of both diseases particularly in already endemic areas. The predicted expansion towards higher altitudes and temperate regions suggests that outbreaks can occur in areas where people might be immunologically naive and public health systems unprepared. The population at risk of malaria and dengue will be higher in densely populated urban areas in the WHO African region, South-East Asia region, and the region of the Americas, although we did not account for urban-heat island effects, which can further alter the risk of disease transmission.

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  • 3. DiSera, Laurel
    et al.
    Sjödin, Henrik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Rocklöv, Joacim
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Tozan, Yesim
    Súdre, Bertrand
    Zeller, Herve
    Muñoz, Ángel G
    The Mosquito, the Virus, the Climate: An Unforeseen Réunion in 20182020Ingår i: GeoHealth, E-ISSN 2471-1403, Vol. 4, nr 8, artikel-id e2020GH000253Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The 2018 outbreak of dengue in the French overseas department of Réunion was unprecedented in size and spread across the island. This research focuses on the cause of the outbreak, asserting that climate played a large role in the proliferation of the Aedes albopictus mosquitoes, which transmitted the disease, and led to the dengue outbreak in early 2018. A stage‐structured model was run using observed temperature and rainfall data to simulate the life cycle and abundance of the Ae. albopictus mosquito. Further, the model was forced with bias‐corrected subseasonal forecasts to determine if the event could have been forecast up to 4 weeks in advance. With unseasonably warm temperatures remaining above 25°C, along with large tropical‐cyclone‐related rainfall events accumulating 10–15 mm per event, the modeled Ae. albopictus mosquito abundance did not decrease during the second half of 2017, contrary to the normal behavior, likely contributing to the large dengue outbreak in early 2018. Although subseasonal forecasts of rainfall for the December–January period in Réunion are skillful up to 4 weeks in advance, the outbreak could only have been forecast 2 weeks in advance, which along with seasonal forecast information could have provided enough time to enhance preparedness measures. Our research demonstrates the potential of using state‐of‐the‐art subseasonal climate forecasts to produce actionable subseasonal dengue predictions. To the best of the authors' knowledge, this is the first time subseasonal forecasts have been used this way.

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  • 4.
    Englund, Göran
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Sjödin, Henrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Bonsall, Michael
    Oxford University.
    Cianelli, Lorenzo
    Oregon State University.
    Frank, Kenneth
    Bedford Institute of Oceanography.
    Heino, Mikko
    University of Bergen.
    Janssen, Arne
    University of Amsterdam.
    Leonardsson, Kjell
    Swedish University of Agricultural Science.
    van der Meer, Jaap
    Royal Netherlands Institute for Sea Research.
    Nachman, Gösta
    Copenhagen University.
    Yu, Jun
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Density dependence induced by the spatial covariance between predators and preyManuskript (preprint) (Övrigt vetenskapligt)
  • 5.
    Farooq, Zia
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Rocklöv, Joacim
    Heidelberg institute of global health and Interdisciplinary center for scientific computing, University of Heidelberg, Im Neuenheimer Feld 205, Heidelberg, Germany.
    Wallin, Jonas
    Department of statistics, Lund university, Sweden.
    Abiri, Najmeh
    Department of statistics, Lund university, Sweden.
    Sewe, Maquins Odhiambo
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Sjödin, Henrik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Semenza, Jan C.
    Heidelberg institute of global health and Interdisciplinary center for scientific computing, University of Heidelberg, Im Neuenheimer Feld 205, Heidelberg, Germany.
    Artificial intelligence to predict West Nile virus outbreaks with eco-climatic drivers2022Ingår i: The Lancet Regional Health: Europe, E-ISSN 2666-7762, Vol. 17, artikel-id 100370Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: In Europe, the frequency, intensity, and geographic range of West Nile virus (WNV)-outbreaks have increased over the past decade, with a 7.2-fold increase in 2018 compared to 2017, and a markedly expanded geographic area compared to 2010. The reasons for this increase and range expansion remain largely unknown due to the complexity of the transmission pathways and underlying disease drivers. In a first, we use advanced artificial intelligence to disentangle the contribution of eco-climatic drivers to WNV-outbreaks across Europe using decade-long (2010-2019) data at high spatial resolution. Methods: We use a high-performance machine learning classifier, XGBoost (eXtreme gradient boosting) combined with state-of-the-art XAI (eXplainable artificial intelligence) methodology to describe the predictive ability and contribution of different drivers of the emergence and transmission of WNV-outbreaks in Europe, respectively. Findings: Our model, trained on 2010-2017 data achieved an AUC (area under the receiver operating characteristic curve) score of 0.97 and 0.93 when tested with 2018 and 2019 data, respectively, showing a high discriminatory power to classify a WNV-endemic area. Overall, positive summer/spring temperatures anomalies, lower water availability index (NDWI), and drier winter conditions were found to be the main determinants of WNV-outbreaks across Europe. The climate trends of the preceding year in combination with eco-climatic predictors of the first half of the year provided a robust predictive ability of the entire transmission season ahead of time. For the extraordinary 2018 outbreak year, relatively higher spring temperatures and the abundance of Culex mosquitoes were the strongest predictors, in addition to past climatic trends. Interpretation: Our AI-based framework can be deployed to trigger rapid and timely alerts for active surveillance and vector control measures in order to intercept an imminent WNV-outbreak in Europe. Funding: The work was partially funded by the Swedish Research Council FORMAS for the project ARBOPREVENT (grant agreement 2018-05973).

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  • 6.
    Farooq, Zia
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Semenza, Jan C.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Rocklöv, Joacim
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Singh, Pratik
    Heidelberg University, Heidelberg, Germany.
    Sjödin, Henrik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Assessing transcontinental threats of dengue outbreaks using human mobility and climatic suitabilityManuskript (preprint) (Övrigt vetenskapligt)
  • 7.
    Farooq, Zia
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Sjödin, Henrik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Semenza, Jan C.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa. Heidelberg institute of global health and Interdisciplinary center for scientific computing, University of Heidelberg, Im Neuenheimer Feld 205, Heidelberg, Germany.
    Tozan, Yesim
    School of Global Public Health, New York University, New York, United States.
    Sewe, Maquins Odhiambo
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Wallin, Jonas
    Department of statistics, Lund university, Sweden.
    Rocklöv, Joacim
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa. Heidelberg institute of global health and Interdisciplinary center for scientific computing, University of Heidelberg, Im Neuenheimer Feld 205, Heidelberg, Germany.
    European projections of West Nile virus transmission under climate change scenarios2023Ingår i: One Health, ISSN 2352-7714, Vol. 16, artikel-id 100509Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    West Nile virus (WNV), a mosquito-borne zoonosis, has emerged as a disease of public health concern in Europe. Recent outbreaks have been attributed to suitable climatic conditions for its vectors favoring transmission. However, to date, projections of the risk for WNV expansion under climate change scenarios is lacking. Here, we estimate the WNV-outbreaks risk for a set of climate change and socioeconomic scenarios. We delineate the potential risk-areas and estimate the growth in the population at risk (PAR). We used supervised machine learning classifier, XGBoost, to estimate the WNV-outbreak risk using an ensemble climate model and multi-scenario approach. The model was trained by collating climatic, socioeconomic, and reported WNV-infections data (2010−22) and the out-of-sample results (1950–2009, 2023–99) were validated using a novel Confidence-Based Performance Estimation (CBPE) method. Projections of area specific outbreak risk trends, and corresponding population at risk were estimated and compared across scenarios. Our results show up to 5-fold increase in West Nile virus (WNV) risk for 2040-60 in Europe, depending on geographical region and climate scenario, compared to 2000-20. The proportion of disease-reported European land areas could increase from 15% to 23-30%, putting 161 to 244 million people at risk. Across scenarios, Western Europe appears to be facing the largest increase in the outbreak risk of WNV. The increase in the risk is not linear but undergoes periods of sharp changes governed by climatic thresholds associated with ideal conditions for WNV vectors. The increased risk will require a targeted public health response to manage the expansion of WNV with climate change in Europe.

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  • 8. Hunsicker, Mary E.
    et al.
    Ciannelli, Lorenzo
    Bailey, Kevin M.
    Buckel, Jeffrey A.
    White, J. Wilson
    Link, Jason S.
    Essington, Timothy E.
    Gaichas, Sarah
    Anderson, Todd W.
    Brodeur, Richard D.
    Chan, Kung-Sik
    Chen, Kun
    Englund, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå marina forskningscentrum (UMF).
    Frank, Kenneth T.
    Freitas, Vania
    Hixon, Mark A.
    Hurst, Thomas
    Johnson, Darren W.
    Kitchell, James F.
    Reese, Doug
    Rose, George A.
    Sjödin, Henrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå marina forskningscentrum (UMF).
    Sydeman, William J.
    van der Veer, Henk W.
    Vollset, Knut
    Zador, Stephani
    Functional responses and scaling in predator-prey interactions of marine fishes: contemporary issues and emerging concepts2011Ingår i: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 14, nr 12, s. 1288-1299Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Predatorprey interactions are a primary structuring force vital to the resilience of marine communities and sustainability of the worlds oceans. Human influences on marine ecosystems mediate changes in species interactions. This generality is evinced by the cascading effects of overharvesting top predators on the structure and function of marine ecosystems. It follows that ecological forecasting, ecosystem management, and marine spatial planning require a better understanding of food web relationships. Characterising and scaling predatorprey interactions for use in tactical and strategic tools (i.e. multi-species management and ecosystem models) are paramount in this effort. Here, we explore what issues are involved and must be considered to advance the use of predatorprey theory in the context of marine fisheries science. We address pertinent contemporary ecological issues including (1) the approaches and complexities of evaluating predator responses in marine systems; (2) the scaling up of predatorprey interactions to the population, community, and ecosystem level; (3) the role of predatorprey theory in contemporary fisheries and ecosystem modelling approaches; and (4) directions for the future. Our intent is to point out needed research directions that will improve our understanding of predatorprey interactions in the context of the sustainable marine fisheries and ecosystem management.

  • 9.
    Phyo Myint, E.E.
    et al.
    Tropical and Parasitic Diseases Research Unit, Graduate Studies Division, Faculty of Medicine, Mahasarakham University, Mahasarakham, Thailand; Mahasarakham University, Mahasarakham, Thailand.
    Sereemaspun, A.
    Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
    Sjödin, H.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Rocklöv, J.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Lai, Y.S.
    Department of Medical statistics, School of Public Health, Sun Yat-sen University, Guangzhou, China.
    Ribas, A.
    Department of Biology, Health and Environment, Faculty of Pharmacy and Food Science, University of Barcelona, Spain.
    Pakdeenarong, N.
    Department of Biology Faculty of Science, Mahasarakham University, Kantharawichai District, MahaSaraham Province, Thailand.
    Nithikathkul, C.
    Tropical and Parasitic Diseases Research Unit, Graduate Studies Division, Faculty of Medicine, Mahasarakham University, Mahasarakham, Thailand; Mahasarakham University, Mahasarakham, Thailand.
    Surveillance Model of Parasitic Zoonosis in Cyprinoid Fishes in Northern Zone and Northeastern Zone of Thailand and Myanmar Using GIS2022Ingår i: International Journal of Geoinformatics, ISSN 1686-6576, Vol. 18, nr 2, s. 129-139Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The parasitic zoonosis, opisthorchis viverrini has been an important public health problem in many parts of the globe. In Thailand, fish-borne parasitic zoonosis is highly spread in the northern and northeastern regions, where a large impact of cholangiocarcinoma occurs, a crucial source of the liver cancer. The rare occasions reports date published about the Opisthorchiasis in the middle zone of Myanmar. In our study, a total of a few species of fish borne trematode metacercariae i.e.; three kind of small intestinal flukes, the family of Heterophyidae; Haplorchoides sp., Haplorchis pumilio, Haplorchis taichi and one species of carcinogenic liver fluke, the family of Opisthorchiidae; Opisthorchis viverrini have been detected from seven study areas from Thailand and Myanmar. The geographic information relevant with the rate of infection with vulnerable species of freshwater fishes was also posted from Thailand and Myanmar, and built a parasitic diseases combine with georeference for Geographical Information System (GIS) implementation. Furthermore, secondary descriptive analysis of the prevalence of fishborne trematodes metacercariae from countries of golden triangles (Southeast Asia) ie; Thailand, Myanmar, and Laos PDR have been created a GIS database for infection status of parasite infections. The outcome from this study may be helpful in strategies for protocol of the prevention of parasitic zoonosis in freshwater fishes reportin Thailand and Myanmar.

  • 10.
    Rocklöv, Joacim
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Sjödin, Henrik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    High population densities catalyse the spread of COVID-192020Ingår i: Journal of Travel Medicine, ISSN 1195-1982, E-ISSN 1708-8305, Vol. 27, nr 3, artikel-id taaa038Artikel i tidskrift (Refereegranskat)
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  • 11.
    Rocklöv, Joacim
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Sjödin, Henrik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Wilder-Smith, Annelies
    Umeå universitet, Medicinska fakulteten, Institutionen för epidemiologi och global hälsa. Department of Disease Control, London School of Hygiene and Tropical Medicine, UK; Heidelberg Institute of Global Health, University of Heidelberg, Germany.
    COVID-19 outbreak on the Diamond Princess cruise ship: estimating the epidemic potential and effectiveness of public health countermeasures2020Ingår i: Journal of Travel Medicine, ISSN 1195-1982, E-ISSN 1708-8305, Vol. 27, nr 3, artikel-id taaa030Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: Cruise ships carry a large number of people in confined spaces with relative homogeneous mixing. On 3 February, 2020, an outbreak of COVID-19 on cruise ship Diamond Princess was reported with 10 initial cases, following an index case on board around 21-25 January. By 4 February, public health measures such as removal and isolation of ill passengers and quarantine of non-ill passengers were implemented. By 20 February, 619 of 3,700 passengers and crew (17%) were tested positive.

    METHODS: We estimated the basic reproduction number from the initial period of the outbreak using (SEIR) models. We calibrated the models with transient functions of countermeasures to incidence data. We additionally estimated a counterfactual scenario in absence of countermeasures, and established a model stratified by crew and guests to study the impact of differential contact rates among the groups. We also compared scenarios of an earlier versus later evacuation of the ship.

    RESULTS: The basic reproduction rate was initially 4 times higher on-board compared to the ${R}_0$ in the epicentre in Wuhan, but the countermeasures lowered it substantially. Based on the modeled initial ${R}_0$ of 14.8, we estimated that without any interventions within the time period of 21 January to 19 February, 2920 out of the 3700 (79%) would have been infected. Isolation and quarantine therefore prevented 2307 cases, and lowered the ${R}_0$ to 1.78. We showed that an early evacuation of all passengers on 3 February would have been associated with 76 infected persons in their incubation time.

    CONCLUSIONS: The cruise ship conditions clearly amplified an already highly transmissible disease. The public health measures prevented more than 2000 additional cases compared to no interventions. However, evacuating all passengers and crew early on in the outbreak would have prevented many more passengers and crew from infection.

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  • 12.
    Sjödin, Henrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Population-level consequences of spatial interactions2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    How is the nature of populations governed by the movement decisions made by their members? This is the core question in this thesis. To answer this question, I first assume that s movement decisions are based on conditions in their local environment. Then I derive mathematical relationships that distil the character of individual movement events, and relate the sum of these events to the dynamical properties of the population. I find that the fate of populations depend delicately on the way resident individuals relocate in response to local conditions. This general conclusion is supported by results in the four papers constituting this thesis.

    In the first paper we derive a deterministic approximation of a stochastic individual-based spatial predator-prey model. We show how general types of movement behaviors either stabilise or destabilise predator-prey dynamics. Based on experimental data on movement behaviors, we conclude that predator-prey dynamics are stabilised if the prey species respond stronger to predator presence than the predatory species respond to prey.

    In the second paper we derive a new type of functional response that arise when there is a behavioral spatial “race” between predators and prey. Although fundamentally different from classical functional responses, the induced density-dependencies in reproduction rates are similar to those in Holling’s type II and DeAngelis-Beddington’s functional responses.

    In the third paper we perform a novel systematic investigation of density-dependencies in population growth-rates induced by the spatial covariance in empirical predator-prey systems. We categorise three types of density dependencies: “lagged”, “direct” and “independent”, and find direct and especially lagged density-dependencies to be common. We find that the density-dependencies in most cases are destabilising, which is at odds with the wide-spread view that spatial heterogeneity stabilises consumer-resource dynamics. We also find dependencies of prey density to be more common than of predator density.

    In the forth paper we consider the evolution of cooperation. We formulate a stochastic individual-based group-formation process and show that profit-dependent group disengagement is evolutionarily stable and allows the emergence of stable cooperative communities.

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    Population-level Consequences of Spatial Interactions
  • 13.
    Sjödin, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Dieckmann, Ulf
    Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Mazzucco, Rupert
    Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Contingent dispersal and the formation of cooperative groupsManuskript (preprint) (Övrigt vetenskapligt)
  • 14.
    Sjödin, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Englund, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Space race functional responses2015Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 282, nr 1801, artikel-id 20142121Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We derive functional responses under the assumption that predators and prey are engaged in a space race in which prey avoid patches with many predators and predators avoid patches with few or no prey. The resulting functional response models have a simple structure and include functions describing how the emigration of prey and predators depend on interspecific densities. As such, they provide a link between dispersal behaviours and community dynamics. The derived functional response is general but is here modelled in accordance with empirically documented emigration responses. We find that the prey emigration response to predators has stabilizing effects similar to that of the DeAngelis-Beddington functional response, and that the predator emigration response to prey has destabilizing effects similar to that of the Holing type 11 response. A stability criterion describing the net effect of the two emigration responses on a Lotka-Volterra predator-prey system is presented. The winner of the space race (i.e. whether predators or prey are favoured) is determined by the relationship between the slopes of the species' emigration responses. It is predicted that predators win the space race in poor habitats, where predator and prey densities are low, and that prey are more successful in richer habitats.

  • 15.
    Sjödin, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Söderquist, Mårten
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Englund, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Population-level consequences of heterospecific density-dependent movements in predator-prey systems2014Ingår i: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 342, s. 93-106Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper we elucidate how small-scale movements, such as those associated with searching for food and avoiding predators, affect the stability of predator-prey dynamics. We investigate an individual-based Lotka-Volterra model with density-dependent movement, in which the predator and prey populations live in a very large number of coupled patches. The rates at which individuals leave patches depend on the local densities of heterospecifics, giving rise to one reaction norm for each of the two species. Movement rates are assumed to be much faster than demographics rates. A spatial structure of predators and prey emerges which affects the global population dynamics. We derive a criterion which reveals how demographic stability depends on the relationships between the per capita covariance and densities of predators and prey. Specifically, we establish that a positive relationship with prey density and a negative relationship with predator density tend to be stabilizing. On a more mechanistic level we show how these relationships are linked to the movement reaction norms of predators and prey. Numerical results show that these findings hold both for local and global movements, i.e., both when migration is biased towards neighbouring patches and when all patches are reached with equal probability.

  • 16.
    Sjödin, Henrik
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Johansson, Anders F.
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Evolution and Ecology Program, International Institute for Applied Systems Analysis, Laxenburg, Austria..
    Farooq, Zia
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Kriit, Hedi Katre
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Wilder-Smith, Annelies
    Umeå universitet, Medicinska fakulteten, Institutionen för epidemiologi och global hälsa. Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK; Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany.
    Åström, Christofer
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Thunberg, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Anestesiologi och intensivvård.
    Söderquist, Mårten
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Rocklöv, Joacim
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa. Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany..
    COVID-19 healthcare demand and mortality in Sweden in response to non-pharmaceutical mitigation and suppression scenarios2020Ingår i: International Journal of Epidemiology, ISSN 0300-5771, E-ISSN 1464-3685, Vol. 49, nr 5, s. 1443-1453Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: While the COVID-19 outbreak in China now appears suppressed, Europe and the USA have become the epicentres, both reporting many more deaths than China. Responding to the pandemic, Sweden has taken a different approach aiming to mitigate, not suppress, community transmission, by using physical distancing without lockdowns. Here we contrast the consequences of different responses to COVID-19 within Sweden, the resulting demand for care, intensive care, the death tolls and the associated direct healthcare related costs.

    METHODS: We used an age-stratified health-care demand extended SEIR (susceptible, exposed, infectious, recovered) compartmental model for all municipalities in Sweden, and a radiation model for describing inter-municipality mobility. The model was calibrated against data from municipalities in the Stockholm healthcare region.

    RESULTS: Our scenario with moderate to strong physical distancing describes well the observed health demand and deaths in Sweden up to the end of May 2020. In this scenario, the intensive care unit (ICU) demand reaches the pre-pandemic maximum capacity just above 500 beds. In the counterfactual scenario, the ICU demand is estimated to reach ∼20 times higher than the pre-pandemic ICU capacity. The different scenarios show quite different death tolls up to 1 September, ranging from 5000 to 41 000, excluding deaths potentially caused by ICU shortage. Additionally, our statistical analysis of all causes excess mortality indicates that the number of deaths attributable to COVID-19 could be increased by 40% (95% confidence interval: 0.24, 0.57).

    CONCLUSION: The results of this study highlight the impact of different combinations of non-pharmaceutical interventions, especially moderate physical distancing in combination with more effective isolation of infectious individuals, on reducing deaths, health demands and lowering healthcare costs. In less effective mitigation scenarios, the demand on ICU beds would rapidly exceed capacity, showing the tight interconnection between the healthcare demand and physical distancing in the society. These findings have relevance for Swedish policy and response to the COVID-19 pandemic and illustrate the importance of maintaining the level of physical distancing for a longer period beyond the study period to suppress or mitigate the impacts from the pandemic.

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  • 17.
    Sjödin, Henrik
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Wilder-Smith, Annelies
    Umeå universitet, Medicinska fakulteten, Institutionen för epidemiologi och global hälsa. Heidelberg Institute of Global Health, University of Heidelberg, Germany. Department of Disease Control, London School of Hygiene and Tropical Medicine, United Kingdom..
    Osman, Sarah
    Umeå universitet, Medicinska fakulteten, Institutionen för epidemiologi och global hälsa.
    Farooq, Zia
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Rocklöv, Joacim
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Only strict quarantine measures can curb the coronavirus disease (COVID-19) outbreak in Italy, 20202020Ingår i: Eurosurveillance, ISSN 1025-496X, E-ISSN 1560-7917, Vol. 25, nr 13, artikel-id 2000280Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Several Italian towns are under lockdown to contain the COVID-19 outbreak. The level of transmission reduction required for physical distancing interventions to mitigate the epidemic is a crucial question. We show that very high adherence to community quarantine (total stay-home policy) and a small household size is necessary for curbing the outbreak in a locked-down town. The larger the household size and amount of time in the public, the longer the lockdown period needed.

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  • 18. Tozan, Yesim
    et al.
    Sjödin, Henrik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Munoz, Angel G.
    Rocklöv, Joacim
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa. Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany.
    Transmission dynamics of dengue and chikungunya in a changing climate: do we understand the eco-evolutionary response?2020Ingår i: Expert Review of Anti-Infective Therapy, ISSN 1478-7210, E-ISSN 1744-8336, Vol. 18, nr 12, s. 1187-1193Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Introduction: We are witnessing an alarming increase in the burden and range of mosquito-borne arboviral diseases. The transmission dynamics of arboviral diseases is highly sensitive to climate and weather and is further affected by non-climatic factors such as human mobility, urbanization, and disease control. As evidence also suggests, climate-driven changes in species interactions may trigger evolutionary responses in both vectors and pathogens with important consequences for disease transmission patterns.

    Areas covered: Focusing on dengue and chikungunya, we review the current knowledge and challenges in our understanding of disease risk in a rapidly changing climate. We identify the most critical research gaps that limit the predictive skill of arbovirus risk models and the development of early warning systems, and conclude by highlighting the potentially important research directions to stimulate progress in this field.

    Expert opinion: Future studies that aim to predict the risk of arboviral diseases need to consider the interactions between climate modes at different timescales, the effects of the many non-climatic drivers, as well as the potential for climate-driven adaptation and evolution in vectors and pathogens. An important outcome of such studies would be an enhanced ability to promulgate early warning information, initiate adequate response, and enhance preparedness capacity.

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  • 19. van Daalen, Kim R.
    et al.
    Romanello, Marina
    Rocklöv, Joacim
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa. Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany.
    Semenza, Jan C.
    Tonne, Cathryn
    Markandya, Anil
    Dasandi, Niheer
    Jankin, Slava
    Achebak, Hicham
    Ballester, Joan
    Bechara, Hannah
    Callaghan, Max W.
    Chambers, Jonathan
    Dasgupta, Shouro
    Drummond, Paul
    Farooq, Zia
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Gasparyan, Olga
    Gonzalez-Reviriego, Nube
    Hamilton, Ian
    Hänninen, Risto
    Kazmierczak, Aleksandra
    Kendrovski, Vladimir
    Kennard, Harry
    Kiesewetter, Gregor
    Lloyd, Simon J.
    Lotto Batista, Martin
    Martinez-Urtaza, Jaime
    Milà, Carles
    Minx, Jan C.
    Nieuwenhuijsen, Mark
    Palamarchuk, Julia
    Quijal-Zamorano, Marcos
    Robinson, Elizabeth J. Z.
    Scamman, Daniel
    Schmoll, Oliver
    Sewe, Maquins Odhiambo
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Sjödin, Henrik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Sofiev, Mikhail
    Solaraju-Murali, Balakrishnan
    Springmann, Marco
    Triñanes, Joaquin
    Anto, Josep M.
    Nilsson, Maria
    Umeå universitet, Medicinska fakulteten, Institutionen för epidemiologi och global hälsa.
    Lowe, Rachel
    The 2022 Europe report of the Lancet Countdown on health and climate change: towards a climate resilient future2022Ingår i: The Lancet Public Health, ISSN 2468-2667, Vol. 7, nr 11, s. e942-e965Artikel i tidskrift (Refereegranskat)
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