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  • 1.
    Altmejd, Adam
    et al.
    Swedish Institute for Social Research, Stockholm University, Stockholm, Sweden; Department of Finance, Stockholm School of Economics, Stockholm, Sweden.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health. Heidelberg Institute of Global Health (HIGH), Interdisciplinary Centre for Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany.
    Wallin, Jonas
    Department of Statistics, Lund University, Lund, Sweden.
    Nowcasting COVID-19 statistics reported with delay: A case-study of Sweden and the UK2023In: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 20, no 4Article in journal (Refereed)
    Abstract [en]

    The COVID-19 pandemic has demonstrated the importance of unbiased, real-time statistics of trends in disease events in order to achieve an effective response. Because of reporting delays, real-time statistics frequently underestimate the total number of infections, hospitalizations and deaths. When studied by event date, such delays also risk creating an illusion of a downward trend. Here, we describe a statistical methodology for predicting true daily quantities and their uncertainty, estimated using historical reporting delays. The methodology takes into account the observed distribution pattern of the lag. It is derived from the "removal method"-a well-established estimation framework in the field of ecology.

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  • 2.
    Armando, Chaibo Jose
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health. Heidelberg Institute of Global Health and Interdisciplinary Centre for Scientific Computing, Heidelberg University, Heidelberg, Germany.
    Sidat, Mohsin
    Faculty of Medicine, Eduardo Mondlane University, Maputo, Mozambique.
    Tozan, Yesim
    School of Global Public Health, New York University, NY, New York, United States.
    Mavume, Alberto Francisco
    Faculty of Science, Eduardo Mondlane University, Maputo, Mozambique.
    Bunker, Aditi
    Center for Climate, Health, and the Global Environment, Harvard T.H. Chan School of Public Health, MA, Boston, United States; Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany.
    Sewe, Maquins Odhiambo
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health. Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany.
    Climate variability, socio-economic conditions and vulnerability to malaria infections in Mozambique 2016–2018: a spatial temporal analysis2023In: Frontiers in Public Health, E-ISSN 2296-2565, Vol. 11, article id 1162535Article in journal (Refereed)
    Abstract [en]

    Background: Temperature, precipitation, relative humidity (RH), and Normalized Different Vegetation Index (NDVI), influence malaria transmission dynamics. However, an understanding of interactions between socioeconomic indicators, environmental factors and malaria incidence can help design interventions to alleviate the high burden of malaria infections on vulnerable populations. Our study thus aimed to investigate the socioeconomic and climatological factors influencing spatial and temporal variability of malaria infections in Mozambique.

    Methods: We used monthly malaria cases from 2016 to 2018 at the district level. We developed an hierarchical spatial–temporal model in a Bayesian framework. Monthly malaria cases were assumed to follow a negative binomial distribution. We used integrated nested Laplace approximation (INLA) in R for Bayesian inference and distributed lag nonlinear modeling (DLNM) framework to explore exposure-response relationships between climate variables and risk of malaria infection in Mozambique, while adjusting for socioeconomic factors.

    Results: A total of 19,948,295 malaria cases were reported between 2016 and 2018 in Mozambique. Malaria risk increased with higher monthly mean temperatures between 20 and 29°C, at mean temperature of 25°C, the risk of malaria was 3.45 times higher (RR 3.45 [95%CI: 2.37–5.03]). Malaria risk was greatest for NDVI above 0.22. The risk of malaria was 1.34 times higher (1.34 [1.01–1.79]) at monthly RH of 55%. Malaria risk reduced by 26.1%, for total monthly precipitation of 480 mm (0.739 [95%CI: 0.61–0.90]) at lag 2 months, while for lower total monthly precipitation of 10 mm, the risk of malaria was 1.87 times higher (1.87 [1.30–2.69]). After adjusting for climate variables, having lower level of education significantly increased malaria risk (1.034 [1.014–1.054]) and having electricity (0.979 [0.967–0.992]) and sharing toilet facilities (0.957 [0.924–0.991]) significantly reduced malaria risk.

    Conclusion: Our current study identified lag patterns and association between climate variables and malaria incidence in Mozambique. Extremes in climate variables were associated with an increased risk of malaria transmission, peaks in transmission were varied. Our findings provide insights for designing early warning, prevention, and control strategies to minimize seasonal malaria surges and associated infections in Mozambique a region where Malaria causes substantial burden from illness and deaths.

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  • 3.
    Armando, Chaibo Jose
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health. Eduardo Mondlane University, Maputo, Mozambique.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health. Heidelberg Institute of Global Health and Interdisciplinary Centre for Scientific Computing, Heidelberg University, Heidelberg, Germany.
    Sidat, Mohsin
    Eduardo Mondlane University, Maputo, Mozambique.
    Tozan, Yesim
    School of Global Public Health, NYU, NY, United States.
    Mavume, Alberto Francisco
    Eduardo Mondlane University, Maputo, Mozambique.
    Bunker, Aditi
    Heidelberg Institute of Global Health, Heidelberg University, Heidelberg, Germany.
    Sewe, Maquins Odhiambo
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health. Universitatsklinikum Heidelberg Heidelberg Institute of Global Health, Heidelberg, Germany.
    Spatial-temporal analysis of climate and socioeconomic conditions on cholera incidence in Mozambique from 2000 to 2018: an ecological longitudinal retrospective study2024In: BMJ Open, E-ISSN 2044-6055, Vol. 14, no 8, article id e082503Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: This study aims to assess both socioeconomic and climatic factors of cholera morbidity in Mozambique considering both spatial and temporal dimensions.

    DESIGN: An ecological longitudinal retrospective study using monthly provincial cholera cases from Mozambican Ministry of Health between 2000 and 2018. The cholera cases were linked to socioeconomic data from Mozambique Demographic and Health Surveys conducted in the period 2000-2018 and climatic data; relative humidity (RH), mean temperature, precipitation and Normalised Difference Vegetation Index (NDVI). A negative binomial regression model in a Bayesian framework was used to model cholera incidence while adjusting for the spatiotemporal covariance, lagged effect of environmental factors and the socioeconomic indicators.

    SETTING: Eleven provinces in Mozambique.

    RESULTS: Over the 19-year period, a total of 153 941 cholera cases were notified to the surveillance system in Mozambique. Risk of cholera increased with higher monthly mean temperatures above 24°C in comparison to the reference mean temperature of 23°C. At mean temperature of 19°C, cholera risk was higher at a lag of 5-6 months. At a shorter lag of 1 month, precipitation of 223.3 mm resulted in an 57% increase in cholera risk (relative risk, RR 1.57 (95% CI 1.06 to 2.31)). Cholera risk was greatest at 3 lag months with monthly NDVI of 0.137 (RR 1.220 (95% CI 1.042 to 1.430)), compared with the reference value of 0.2. At an RH of 54%, cholera RR was increased by 62% (RR 1.620 (95% CI 1.124 to 2.342)) at a lag of 4 months. We found that ownership of radio RR 0.29, (95% CI 0.109 to 0.776) and mobile phones RR 0.262 (95% CI 0.097 to 0.711) were significantly associated with low cholera risk.

    CONCLUSION: The derived lagged patterns can provide appropriate lead times in a climate-driven cholera early warning system that could contribute to the prevention and management of outbreaks.

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  • 4.
    Aström, Daniel Oudin
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Forsberg, Bertil
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Edvinsson, Sören
    Umeå University, Faculty of Social Sciences, Centre for Population Studies (CPS). Ageing & Living Condit Programme, Umeå University.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Acute Fatal Effects of Short-Lasting Extreme Temperatures in Stockholm, Sweden: Evidence Across a Century of Change.2013In: Epidemiology, ISSN 1044-3983, E-ISSN 1531-5487, Vol. 24, no 6, p. 820-829Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Climate change is projected to increase the frequency of extreme weather events. Short-term effects of extreme hot and cold weather and their effects on mortality have been thoroughly documented, as have epidemiologic and demographic changes throughout the 20th century. We investigated whether sensitivity to episodes of extreme heat and cold has changed in Stockholm, Sweden, from the beginning of the 20th century until the present.

    METHODS: We collected daily mortality and temperature data for the period 1901-2009 for present-day Stockholm County, Sweden. Heat extremes were defined as days for which the 2-day moving average of mean temperature was above the 98th percentile; cold extremes were defined as days for which the 26-day moving average was below the 2nd percentile. The relationship between extreme hot/cold temperatures and all-cause mortality, stratified by decade, sex, and age, was investigated through time series modeling, adjusting for time trends.

    RESULTS: Total daily mortality was higher during heat extremes in all decades, with a declining trend over time in the relative risk associated with heat extremes, leveling off during the last three decades. The relative risk of mortality was higher during cold extremes for the entire period, with a more dispersed pattern across decades. Unlike for heat extremes, there was no decline in the mortality with cold extremes over time.

    CONCLUSIONS: Although the relative risk of mortality during extreme temperature events appears to have fallen, such events still pose a threat to public health.

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  • 5. Barnett, A. G.
    et al.
    Hajat, S.
    Gasparrini, A.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Cold and heat waves in the United States2012In: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 112, p. 218-224Article in journal (Refereed)
    Abstract [en]

    Extreme cold and heat waves, characterized by a number of cold or hot days in succession, place a strain on people's cardiovascular and respiratory systems. The increase in deaths due to these waves may be greater than that predicted by extreme temperatures alone. We examined cold and heat waves in 99 US cities for 14 years (1987-2000) and investigated how the risk of death depended on the temperature threshold used to define a wave, and a wave's timing, duration and intensity. We defined cold and heat waves using temperatures above and below cold and heat thresholds for two or more days. We tried five cold thresholds using the first to fifth percentiles of temperature, and five heat thresholds using the 95-99 percentiles. The extra wave effects were estimated using a two-stage model to ensure that their effects were estimated after removing the general effects of temperature. The increases in deaths associated with cold waves were generally small and not statistically significant, and there was even evidence of a decreased risk during the coldest waves. Heat waves generally increased the risk of death, particularly for the hottest heat threshold. Cold waves of a colder intensity or longer duration were not more dangerous. Cold waves earlier in the cool season were more dangerous, as were heat waves earlier in the warm season. In general there was no increased risk of death during cold waves above the known increased risk associated with cold temperatures. Cold or heat waves earlier in the cool or warm season may be more dangerous because of a build up in the susceptible pool or a lack of preparedness for extreme temperatures.

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  • 6.
    Bowman, Leigh
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), Geneva, Switzerland.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Kroeger, Axel
    Olliaro, Piero
    Skewes, Ronald
    A comparison of Zika and dengue outbreaks using national surveillance data in the Dominican Republic2018In: PLoS Neglected Tropical Diseases, ISSN 1935-2727, E-ISSN 1935-2735, Vol. 12, no 11, article id e0006876Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Aedes-borne arboviruses continue to precipitate epidemics worldwide. In Dominican Republic, the appearance of Zika virus cases that closely followed a large dengue epidemic provided an opportunity to study the different transmission drivers behind these two flaviviruses. Retrospective datasets were used to collect information on the populations at risk and descriptive statistics were used to describe the outbreaks on a national scale.

    METHODOLOGY/ PRINCIPAL FINDINGS: Expectedly, box plots showed that 75% of dengue was reported in those aged <20 years while Zika infections were more widely dispersed among the population. Dengue attack rates were marginally higher among males at 25.9 per 10,000 population vs. 21.5 per 10,000 population for females. Zika infections appeared to be highly clustered among females (73.8% (95% CI 72.6%, 75.0%; p<0.05)); age-adjusted Zika attack rates among females were 7.64 per 10,000 population compared with 2.72 per 10,000 population among males. R0 calculations stratified by sex also showed a significantly higher metric among females: 1.84 (1.82, 1.87; p<0.05) when compared to males at 1.72 (1.69, 1.75; p<0.05). However, GBS attack rates stratified by sex revealed slightly higher risk in males vs. females, at 0.62 and 0.57 per 10,000 population respectively.

    CONCLUSIONS/ SIGNIFICANCE: Evidence suggests little impact of existing dengue immunity on reported attack rates of Zika at the population level. Confounding of R0 and incident risk calculations by sex-specific over-reporting can alter the reliability of epidemiological metrics, which could be addressed using associated proxy syndromes or conditions to explore seemingly sex-skewed incidence. The findings indicate that community awareness campaigns, through influencing short-term health seeking behaviour, remain the most plausible mechanism behind increased reporting among women of reproductive age, although biological susceptibility cannot yet be ruled out. Media campaigns and screening are therefore recommended for women of reproductive age during Zika outbreaks. Future research should focus on clinical Zika outcomes among dengue seropositive individuals.

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  • 7.
    Brännström, Åke
    et al.
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics. Advancing Systems Analysis Program, International Institute for Applied Systems Analysis, Laxenburg, Austria.
    Sjödin, Henrik
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    A Method for Estimating the Number of Infections From the Reported Number of Deaths2022In: Frontiers in Public Health, E-ISSN 2296-2565, Vol. 9, article id 648545Article in journal (Refereed)
    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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  • 8. Bunker, Aditi
    et al.
    Sewe, Maquins Odhiambo
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Sié, Ali
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Sauerborn, Rainer
    Excess burden of non-communicable disease years of life lost from heat in rural Burkina Faso: a time series analysis of the years 2000-20102017In: BMJ Open, E-ISSN 2044-6055, Vol. 7, no 11, article id e018068Article in journal (Refereed)
    Abstract [en]

    Objectives: Investigate the association of heat exposure on years of life lost (YLL) from non-communicable diseases (NCD) in Nouna, Burkina Faso, between 2000 and 2010.

    Design: Daily time series regression analysis using distributed lag non-linear models, assuming a quasi-Poisson distribution of YLL.

    Setting: Nouna Health and Demographic Surveillance System, Kossi Province, Rural Burkina Faso.

    Participants: 18 367 NCD-YLL corresponding to 790 NCD deaths recorded in the Nouna Health and Demographic Surveillance Site register over 11 years.

    Main outcome measure: Excess mean daily NCD-YLL were generated from the relative risk of maximum daily temperature on NCD-YLL, including effects delayed up to 14 days.

    Results: Daily average NCD-YLL were 4.6, 2.4 and 2.1 person-years for all ages, men and women, respectively. Moderate 4-day cumulative rise in maximum temperature from 36.4 degrees C (50th percentile) to 41.4 degrees C (90th percentile) resulted in 4.44 (95% CI 0.24 to 12.28) excess daily NCDYLL for all ages, rising to 7.39 (95% CI 0.32 to 24.62) at extreme temperature (42.8 degrees C; 99th percentile). The strongest health effects manifested on the day of heat exposure (lag 0), where 0.81 (95% CI 0.13 to 1.59) excess mean NCD-YLL occurred daily at 41.7 degrees C compared with 36.4 degrees C, diminishing in statistical significance after 4 days. At lag 0, daily excess mean NCD-YLL were higher for men, 0.58 (95% CI 0.11 to 1.15) compared with women, 0.15 (95% CI -0.25 to 9.63) at 41.7 degrees C vs 36.4 degrees C.

    Conclusion: Premature death from NCD was elevated significantly with moderate and extreme heat exposure. These findings have important implications for developing adaptation and mitigation strategies to reduce ambient heat exposure and preventive measures for limiting NCD in Africa.

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  • 9. Bunker, Aditi
    et al.
    Wildenhain, Jan
    Vandenbergh, Alina
    Henschke, Nicholas
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Hajat, Shakoor
    Sauerborn, Rainer
    Effects of Air Temperature on Climate-Sensitive Mortality and Morbidity Outcomes in the Elderly; a Systematic Review and Meta-analysis of Epidemiological Evidence2016In: EBioMedicine, E-ISSN 2352-3964, Vol. 6, p. 258-268Article, review/survey (Refereed)
    Abstract [en]

    Introduction: Climate change and rapid population ageing are significant public health challenges. Understanding which health problems are affected by temperature is important for preventing heat and cold-related deaths and illnesses, particularly in the elderly. Here we present a systematic review and meta-analysis on the effects of ambient hot and cold temperature (excluding heat/cold wave only studies) on elderly (65+ years) mortality and morbidity.

    Methods: Time-series or case-crossover studies comprising cause-specific cases of elderly mortality (n = 3,933,398) or morbidity (n = 12,157,782) were pooled to obtain a percent change (%) in risk for temperature exposure on cause-specific disease outcomes using a random-effects meta-analysis. Results: A 1 degrees C temperature rise increased cardiovascular (3.44%, 95% CI 3.10-3.78), respiratory (3.60%, 3.18-4.02), and cerebrovascular (1.40%, 0.06-2.75) mortality. A 1 degrees C temperature reduction increased respiratory (2.90%, 1.84-3.97) and cardiovascular (1.66%, 1.19-2.14) mortality. The greatest risk was associated with cold-induced pneumonia (6.89%, 20-12.99) and respiratory morbidity (4.93% 1.54-8.44). A 1 degrees C temperature rise increased cardiovascular, respiratory, diabetes mellitus, genitourinary, infectious disease and heat-related morbidity.

    Discussion: Elevated risks for the elderly were prominent for temperature-induced cerebrovascular, cardiovascular, diabetes, genitourinary, infectious disease, heat-related, and respiratory outcomes. These risks will likely increase with climate change and global ageing.

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  • 10.
    Béguin, Andreas
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Hales, Simon
    University of Otago, Wellington, New Zealand.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Åström, Christofer
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Louis, Valérie R
    Institute for Public Health, Heidelberg University Hospital, Heidelberg, Germany.
    Sauerborn, Rainer
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    The opposing effects of climate change and socio-economic development on the global distribution of malaria2011In: Global Environmental Change, ISSN 0959-3780, E-ISSN 1872-9495, Vol. 21, no 4, p. 1209-1214Article in journal (Refereed)
    Abstract [en]

    The current global geographic distribution of malaria results from a complex interaction between climatic and non-climatic factors. Over the past century, socio-economic development and public health measures have contributed to a marked contraction in the distribution of malaria. Previous assessments of the potential impact of global changes on malaria have not quantified the effects of non-climate factors. In this paper, we describe an empirical model of the past, present and future-potential geographic distribution of malaria which incorporates both the effects of climate change and of socio-economic development. A logistic regression model using temperature, precipitation and gross domestic product per capita (GDPpc) identifies the recent global geographic distribution of malaria with high accuracy (sensitivity 85% and specificity 95%). Empirically, climate factors have a substantial effect on malaria transmission in countries where GDPpc is currently less than US$20,000. Using projections of future climate, GDPpc and population consistent with the IPCC A1B scenario, we estimate the potential future population living in areas where malaria can be transmitted in 2030 and 2050. In 2050, the projected population at risk is approximately 5.2 billion when considering climatic effects only, 1.95 billion when considering the combined effects of GDP and climate, and 1.74 billion when considering GDP effects only. Under the A1B scenario, we project that climate change has much weaker effects on malaria than GDPpc increase. This outcome is, however, dependent on optimistic estimates of continued socioeconomic development. Even then, climate change has important effects on the projected distribution of malaria, leading to an increase of over 200 million in the projected population at risk.

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  • 11. Caminade, Cyril
    et al.
    Kovats, Sari
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Tompkins, Adrian M
    Morse, Andrew P
    Colón-González, Felipe J
    Stenlund, Hans
    Martens, Pim
    Lloyd, Simon J
    Impact of climate change on global malaria distribution2014In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 111, no 9, p. 3286-3291Article in journal (Refereed)
    Abstract [en]

    Malaria is an important disease that has a global distribution and significant health burden. The spatial limits of its distribution and seasonal activity are sensitive to climate factors, as well as the local capacity to control the disease. Malaria is also one of the few health outcomes that has been modeled by more than one research group and can therefore facilitate the first model intercomparison for health impacts under a future with climate change. We used bias-corrected temperature and rainfall simulations from the Coupled Model Intercomparison Project Phase 5 climate models to compare the metrics of five statistical and dynamical malaria impact models for three future time periods (2030s, 2050s, and 2080s). We evaluated three malaria outcome metrics at global and regional levels: climate suitability, additional population at risk and additional person-months at risk across the model outputs. The malaria projections were based on five different global climate models, each run under four emission scenarios (Representative Concentration Pathways, RCPs) and a single population projection. We also investigated the modeling uncertainty associated with future projections of populations at risk for malaria owing to climate change. Our findings show an overall global net increase in climate suitability and a net increase in the population at risk, but with large uncertainties. The model outputs indicate a net increase in the annual person-months at risk when comparing from RCP2.6 to RCP8.5 from the 2050s to the 2080s. The malaria outcome metrics were highly sensitive to the choice of malaria impact model, especially over the epidemic fringes of the malaria distribution.

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  • 12. Colon-Gonzalez, J. Felipe
    et al.
    Sewe, Maquins Odhiambo
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Tompkins, M. Adrian
    Sjödin, Henrik
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Casallas, Alejandro
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health. 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 study2021In: The Lancet Planetary Health, E-ISSN 2542-5196, Vol. 5, no 7, p. E404-E414Article in journal (Refereed)
    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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  • 13.
    Dapi, Léonie N
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Nguefack-Tsague, Georges
    Tetanye, Ekoe
    Kjellström, Tord
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Heat impact on schoolchildren in Cameroon, Africa: potential health threat from climate change2010In: Global Health Action, ISSN 1654-9716, E-ISSN 1654-9880, Vol. 3, p. Article nr 5610-Article in journal (Refereed)
    Abstract [en]

    Background: Health impacts related to climate change are potentially an increasing problem in Cameroon, especially during hot seasons when there are no means for protective and adaptive actions.

    Objective: To describe environmental conditions in schools and to evaluate the impact of heat on schoolchildren’s health during school days in the Cameroon cities of Yaounde´ and Douala.

    Methods: Schoolchildren (N=285) aged 12=16 years from public secondary schools completed a questionnaire about their background, general symptoms, and hot feelings in a cross-sectional study. In Yaounde´, 50 schoolchildren were individually interviewed during school days about hourly symptoms (fatigue, headache, and feeling very hot) and performance. Lascar dataloggers were used to measure indoor classroom temperatures and humidity.

    Results: There was a significant correlation between daily indoor temperature and the percentages of schoolchildren who felt very hot, had fatigue, and headaches in Yaounde´. A high proportion of schoolchildren felt very hot (48%), had fatigue (76%), and headaches (38%) in Yaounde´. Prevalences (%) were higher among girls than boys for headaches (58 vs 39), feeling ‘very hot overall’ (37 vs 21), and ‘very hot in head’ (21 vs 18). Up to 62% were absentminded and 45% had slow writing speed. High indoor temperatures of 32.58C in Yaounde´ and 36.68C in Douala were observed in school.

    Conclusions: Headache, fatigue, and feeling very hot associated with high indoor air temperature were observed among schoolchildren in the present study. Longitudinal data in schools are needed to confirm these results. School environmental conditions should be improved in order to enhance learning.

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  • 14. Diboulo, Eric
    et al.
    Sie, Ali
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Niamba, Louis
    Ye, Maurice
    Bagagnan, Cheik
    Sauerborn, Rainer
    Univ Heidelberg, Inst Publ Hlth, Heidelberg, Germany.
    Weather and mortality: a 10 year retrospective analysis of the Nouna Health and Demographic Surveillance System, Burkina Faso2012In: Global Health Action, ISSN 1654-9716, E-ISSN 1654-9880, Vol. 5, p. 19078-Article in journal (Refereed)
    Abstract [en]

    Background: A growing body of evidence points to the emission of greenhouse gases from human activity as a key factor in climate change. This in turn affects human health and wellbeing through consequential changes in weather extremes. At present, little is known about the effects of weather on the health of sub-Saharan African populations, as well as the related anticipated effects of climate change partly due to scarcity of good quality data. We aimed to study the association between weather patterns and daily mortality in the Nouna Health and Demographic Surveillance System (HDSS) area during 1999-2009. Methods: Meteorological data were obtained from a nearby weather station in the Nouna HDSS area and linked to mortality data on a daily basis. Time series Poisson regression models were established to estimate the association between the lags of weather and daily population-level mortality, adjusting for time trends. The analyses were stratified by age and sex to study differential population susceptibility. Results: We found profound associations between higher temperature and daily mortality in the Nouna HDSS, Burkina Faso. The short-term direct heat effect was particularly strong on the under-five child mortality rate. We also found independent coherent effects and strong associations between rainfall events and daily mortality, particularly in elderly populations. Conclusion: Mortality patterns in the Nouna HDSS appear to be closely related to weather conditions. Further investigation on cause-specific mortality, as well as on vulnerability and susceptibility is required. Studies on local adaptation and mitigation measures to avoid health impacts from weather and climate change is also needed to reduce negative effects from weather and climate change on population health in rural areas of the sub-Saharan Africa.

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  • 15. DiSera, Laurel
    et al.
    Sjödin, Henrik
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Tozan, Yesim
    Súdre, Bertrand
    Zeller, Herve
    Muñoz, Ángel G
    The Mosquito, the Virus, the Climate: An Unforeseen Réunion in 20182020In: GeoHealth, E-ISSN 2471-1403, Vol. 4, no 8, article id e2020GH000253Article in journal (Refereed)
    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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  • 16. Doum, Dyna
    et al.
    Overgaard, Hans J.
    Mayxay, Mayfong
    Suttiprapa, Sutas
    Saichua, Prasert
    Ekalaksananan, Tipaya
    Tongchai, Panwad
    Rahman, Md. Siddikur
    Haque, Ubydul
    Phommachanh, Sysavanh
    Pongvongsa, Tiengkham
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Paul, Richard
    Pientong, Chamsai
    Dengue Seroprevalence and Seroconversion in Urban and Rural Populations in Northeastern Thailand and Southern Laos2020In: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 17, no 23, article id 9134Article in journal (Refereed)
    Abstract [en]

    Dengue is the most rapidly spreading mosquito-borne viral disease in the world. The detection of clinical cases enables us to measure the incidence of dengue infection, whereas serological surveys give insights into the prevalence of infection. This study aimed to determine dengue seroprevalence and seroconversion rates in northeastern Thailand and southern Laos and to assess any association of mosquito control methods and socioeconomic factors with dengue virus (DENV) infection. Cross-sectional seroprevalence surveys were performed in May and November 2019 on the same individuals. Blood samples were collected from one adult and one child, when possible, in each of 720 randomly selected households from two urban and two rural sites in both northeastern Thailand and southern Laos. IgG antibodies against DENV were detected in serum using a commercial enzyme-linked immunosorbent assay (ELISA) kit. Overall, 1071 individuals participated in the study. The seroprevalence rate was high (91.5%) across all 8 study sites. Only age and province were associated with seroprevalence rates. There were 33 seroconversions during the period from May to November, of which seven reported fever. More than half of the seroconversions occurred in the rural areas and in Laos. Dengue seroconversion was significantly associated with young age (<15 years old), female gender, province, and duration of living in the current residence. No socioeconomic factors or mosquito control methods were found to be associated with seroprevalence or seroconversion. Notably, however, the province with most seroconversions had lower diurnal temperature ranges than elsewhere. In conclusion, our study has highlighted the homogeneity of dengue exposure across a wide range of settings and most notably those from rural and urban areas. Dengue can no longer be considered to be solely an urban disease nor necessarily one linked to poverty.

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  • 17.
    Ebi, Kristie L
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. Umeå Centre for Global Health Research.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. Umeå Centre for Global Health Research.
    Climate change and health modeling: horses for courses2014In: Global Health Action, ISSN 1654-9716, E-ISSN 1654-9880, Vol. 7, p. 24154-Article in journal (Refereed)
    Abstract [en]

    Mathematical and statistical models are needed to understand the extent to which weather, climate variability, and climate change are affecting current and may affect future health burdens in the context of other risk factors and a range of possible development pathways, and the temporal and spatial patterns of any changes. Such understanding is needed to guide the design and the implementation of adaptation and mitigation measures. Because each model projection captures only a narrow range of possible futures, and because models serve different purposes, multiple models are needed for each health outcome ('horses for courses'). Multiple modeling results can be used to bracket the ranges of when, where, and with what intensity negative health consequences could arise. This commentary explores some climate change and health modeling issues, particularly modeling exposure-response relationships, developing early warning systems, projecting health risks over coming decades, and modeling to inform decision-making. Research needs are also suggested.

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  • 18.
    Ebi, Kristie L
    et al.
    Department of Global Health, University of Washington, Seattle, WA, 98195, USA. krisebi@essllc.org..
    Semenza, Jan C
    Stockholm Environmental Institute, Linnégatan 87D, 115 23, Stockholm, Sweden..
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Current medical research funding and frameworks are insufficient to address the health risks of global environmental change2016In: Environmental Health, E-ISSN 1476-069X, Vol. 15, article id 108Article in journal (Refereed)
    Abstract [en]

    Background: Three major international agreements signed in 2015 are key milestones for transitioning to more sustainable and resilient societies: the UN 2030 Agenda for Sustainable Development; the Sendai Framework for Disaster Risk Reduction; and the Paris Agreement under the United Nations Framework Convention on Climate Change. Together, these agreements underscore the critical importance of understanding and managing the health risks of global changes, to ensure continued population health improvements in the face of significant social and environmental change over this century.

    Body: Funding priorities of major health institutions and organizations in the U.S. and Europe do not match research investments with needs to inform implementation of these international agreements. In the U.S., the National Institutes of Health commit 0.025 % of their annual research budget to climate change and health. The European Union Seventh Framework Programme committed 0.08 % of the total budget to climate change and health; the amount committed under Horizon 2020 was 0.04 % of the budget. Two issues apparently contributing to this mismatch are viewing climate change primarily as an environmental problem, and therefore the responsibility of other research streams; and narrowly framing research into managing the health risks of climate variability and change from the perspective of medicine and traditional public health. This reductionist, top-down perspective focuses on proximate, individual level risk factors. While highly successful in reducing disease burdens, this framing is insufficient to protect health and well-being over a century that will be characterized by profound social and environmental changes.

    Conclusions: International commitments in 2015 underscored the significant challenges societies will face this century from climate change and other global changes. However, the low priority placed on understanding and managing the associated health risks by national and international research institutions and organizations leaves populations poorly prepared to cope with changing health burdens. Risk-centered, systems approaches can facilitate understanding of the complex interactions and dependencies across environmental, social, and human systems. This understanding is needed to formulate effective interventions targeting socio-environmental factors that are as important for determining health burdens as are individual risk factors.

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  • 19.
    Egondi, Thaddaeus
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Ettarh, R.
    Kyobutungi, C.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Child morbidity and mortality associated with exposure to inhalable particles (PM2.5) among the urban poor in Nairobi, KenyaManuscript (preprint) (Other academic)
  • 20. Egondi, Thaddaeus
    et al.
    Ettarh, Remare
    Kyobutungi, Catherine
    Ng, Nawi
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Exposure to Outdoor Particles (PM2.5) and Associated Child Morbidity and Mortality in Socially Deprived Neighborhoods of Nairobi, Kenya2018In: Atmosphere, E-ISSN 2073-4433, Vol. 9, no 9, article id 351Article in journal (Refereed)
    Abstract [en]

    Exposure to air pollution is associated with adverse health outcomes. However, the health burden related to ambient outdoor air pollution in sub-Saharan Africa remains unclear. This study examined the relationship between exposure to outdoor air pollution and child health in urban slums of Nairobi, Kenya. We conducted a semi-ecological study among children under 5 years of age from two slum areas and exposure measurements of particulate matter (PM2.5) at the village level were aligned to data from a retrospective cohort study design. We used logistic and Poisson regression models to ascertain the associations between PM2.5 exposure level and child morbidity and mortality. Compared to those in low-pollution areas (PM2.5 < 25 µg/m3), children in high-pollution areas (PM2.5 ≥ 25 µg/m3) were at significantly higher risk for morbidity in general (odds ratio (OR) = 1.25, 95% confidence interval (CI): 1.11–1.41) and, specifically, cough (OR = 1.38, 95% CI: 1.20–1.48). Exposure to high levels of pollution was associated with a high child mortality rate from all causes (IRR = 1.22, 95% CI: 1.08–1.39) and respiratory causes (IRR = 1.12, 95% CI: 0.88–1.42). The findings indicate that there are associated adverse health outcomes with air pollution in urban slums. Further research on air pollution health impact assessments in similar urban areas is required.

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  • 21.
    Egondi, Thaddaeus
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Kyobutungi, Catherine
    Kovats, Sari
    Muindi, Kanyiva
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Ettarh, Remare
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Time-series analysis of weather and mortality patterns in Nairobi's informal settlements2012In: Global Health Action, ISSN 1654-9716, E-ISSN 1654-9880, Vol. 5, p. 23-32Article in journal (Refereed)
    Abstract [en]

    Background: Many studies have established a link between weather (primarily temperature) and daily mortality in developed countries. However, little is known about this relationship in urban populations in sub-Saharan Africa. Objectives: The objective of this study was to describe the relationship between daily weather and mortality in Nairobi, Kenya, and to evaluate this relationship with regard to cause of death, age, and sex. Methods: We utilized mortality data from the Nairobi Urban Health and Demographic Surveillance System and applied time-series models to study the relationship between daily weather and mortality for a population of approximately 60,000 during the period 2003-2008. We used a distributed lag approach to model the delayed effect of weather on mortality, stratified by cause of death, age, and sex. Results: Increasing temperatures (above 75th percentile) were significantly associated with mortality in children and non-communicable disease (NCD) deaths. We found all-cause mortality of shorter lag of same day and previous day to increase by 3.0% for a 1 degree decrease from the 25th percentile of 18 degrees C (not statistically significant). Mortality among people aged 50+ and children aged below 5 years appeared most susceptible to cold compared to other age groups. Rainfall, in the lag period of 0-29 days, increased all-cause mortality in general, but was found strongest related to mortality among females. Low temperatures were associated with deaths due to acute infections, whereas rainfall was associated with all-cause pneumonia and NCD deaths. Conclusions: Increases in mortality were associated with both hot and cold weather as well as rainfall in Nairobi, but the relationship differed with regard to age, sex, and cause of death. Our findings indicate that weather-related mortality is a public health concern for the population in the informal settlements of Nairobi, Kenya, especially if current trends in climate change continue.

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  • 22.
    Egondi, Thaddaeus
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Kyobutungi, Catherine
    Ng, Nawi
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Muindi, Kanyiva
    Oti, Samuel
    van de Vijver, Steven
    Ettarh, Remare
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Community perceptions of air pollution and related health risks in Nairobi slums2013In: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 10, no 10, p. 4851-4868Article in journal (Refereed)
    Abstract [en]

    Air pollution is among the leading global risks for mortality and responsible for increasing risk for chronic diseases. Community perceptions on exposure are critical in determining people's response and acceptance of related policies. Therefore, understanding people' perception is critical in informing the design of appropriate intervention measures. The aim of this paper was to establish levels and associations between perceived pollution and health risk perception among slum residents. A cross-sectional study of 5,317 individuals aged 35+ years was conducted in two slums of Nairobi. Association of perceived score and individual characteristics was assessed using linear regression. Spatial variation in the perceived levels was determined through hot spot analysis using ArcGIS. The average perceived air pollution level was higher among residents in Viwandani compared to those in Korogocho. Perceived air pollution level was positively associated with perceived health risks. The majority of respondents were exposed to air pollution in their place of work with 66% exposed to at least two sources of air pollution. Less than 20% of the respondents in both areas mentioned sources related to indoor pollution. The perceived air pollution level and related health risks in the study community were low among the residents indicating the need for promoting awareness on air pollution sources and related health risks.

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    Community Perceptions of Air Pollution and Related Health Risks in Nairobi Slums
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  • 23.
    Egondi, Thaddaeus
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. African Populat & Hlth Res Ctr, Nairobi, Kenya.
    Kyobutungi, Catherine
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Temperature variation and heat wave and cold spell impacts on years of life lost among the urban poor population of Nairobi, Kenya2015In: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 12, no 3, p. 2735-2748Article in journal (Refereed)
    Abstract [en]

    Weather extremes are associated with adverse health outcomes, including mortality. Studies have investigated the mortality risk of temperature in terms of excess mortality, however, this risk estimate may not be appealing to policy makers assessing the benefits expected for any interventions to be adopted. To provide further evidence of the burden of extreme temperatures, we analyzed the effect of temperature on years of life lost (YLL) due to all-cause mortality among the population in two urban informal settlements. YLL was generated based on the life expectancy of the population during the study period by applying a survival analysis approach. Association between daily maximum temperature and YLL was assessed using a distributed lag nonlinear model. In addition, cold spell and heat wave effects, as defined according to different percentiles, were investigated. The exposure-response curve between temperature and YLL was J-shaped, with the minimum mortality temperature (MMT) of 26 °C. An average temperature of 21 °C compared to the MMT was associated with an increase of 27.4 YLL per day (95% CI, 2.7-52.0 years). However, there was no additional effect for extended periods of cold spells, nor did we find significant associations between YLL to heat or heat waves. Overall, increased YLL from all-causes were associated with cold spells indicating the need for initiating measure for reducing health burdens.

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  • 24.
    Egondi, Thaddaeus
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. African Population and Health Research Center, P.O. Box 10787-00100, Nairobi, Kenya.
    Muindi, Kanyiva
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. African Population and Health Research Center, P.O. Box 10787-00100, Nairobi, Kenya.
    Kyobutungi, C
    Gatari, M
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Measuring exposure levels of inhalable airborne particles (PM2.5) in two socially deprived areas of Nairobi, Kenya2016In: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 148, p. 500-506Article in journal (Refereed)
    Abstract [en]

    Introduction: Ambient air pollution is a growing global health concern tightly connected to the rapid global urbanization. Health impacts from outdoor air pollution exposure amounts to high burdens of deaths and disease worldwide. However, the lack of systematic collection of air pollution and health data in many low-and middle-income countries remains a challenge for epidemiological studies in the local environment. This study aimed to provide a description of the particulate matter (PM2.5) concentration in the poorest urban residential areas of Nairobi, Kenya. Methods: Real-time measurements of (PM2.5) were conducted in two urban informal settlements of Nairobi City, Kenya"s Capital, from February 2013 to October 2013. The measurements were conducted using DustTrak II 8532 hand-held samplers at a height of about 1.5 m above ground level with a resolution of 1-min logging. Sampling took place from early morning to evenings according to a fixed route of measurement within areas including fixed geographical checkpoints. Results: The study period average concentration of PM2.5 was 166 mu g/m(3) in the Korogocho area and 67 mu g/m(3) in the Viwandani area. The PM2.5 levels in both areas reached bimodal daily peaks in the morning and evening. The average peak value of morning concentration in Korogocho was 214 mu g/m(3), and 164 mu g/m(3) in the evening and in Viwandani was 76 mu g/m(3) and 82 mu g/m(3) respectively. The daily midday average low observed during was 146 mu g/m(3) in Korogocho and 59 mu g/m(3) in Viwandani. Conclusion: The results show that residents in both slums are continuously exposed to PM2.5 levels exceeding hazardous levels according to World Health Organization guidelines. The study showed a marked disparity between the two slum areas situated only 7 km apart indicating the local situation and sources to be very important for exposure to PM2.5.

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  • 25.
    Farooq, Zia
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    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 University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Sjödin, Henrik
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    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 drivers2022In: The Lancet Regional Health: Europe, E-ISSN 2666-7762, Vol. 17, article id 100370Article in journal (Refereed)
    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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  • 26.
    Farooq, Zia
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health. 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 University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Sjödin, Henrik
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Semenza, Jan C.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health. Heidelberg Institute of Global Health and Interdisciplinary Center for Scientific Computing, University of Heidelberg, Im Neuenheimer Feld 205, Heidelberg, Germany.
    Input precision, output excellence: the importance of data quality control and method selection in disease risk mapping: authors’ reply2024In: The Lancet Regional Health: Europe, E-ISSN 2666-7762, Vol. 42, article id 100947Article in journal (Refereed)
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  • 27.
    Farooq, Zia
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Semenza, Jan C.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Singh, Pratik
    Heidelberg University, Heidelberg, Germany.
    Sjödin, Henrik
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Assessing transcontinental threats of dengue outbreaks using human mobility and climatic suitabilityManuscript (preprint) (Other academic)
  • 28.
    Farooq, Zia
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Sjödin, Henrik
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Brännström, Åke
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Optimizing case fatality ratio estimates in ongoing pandemics through case-to-death time distribution analysisManuscript (preprint) (Other academic)
  • 29.
    Farooq, Zia
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Sjödin, Henrik
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Semenza, Jan C.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health. 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 University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Wallin, Jonas
    Department of statistics, Lund university, Sweden.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health. 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 scenarios2023In: One Health, ISSN 2352-7714, Vol. 16, article id 100509Article in journal (Refereed)
    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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  • 30. Gasparrini, Antonio
    et al.
    Guo, Yuming
    Hashizume, Masahiro
    Lavigne, Eric
    Zanobetti, Antonella
    Schwartz, Joel
    Tobias, Aurelio
    Tong, Shilu
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Forsberg, Bertil
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Leone, Michela
    De Sario, Manuela
    Bell, Michelle L
    Guo, Yue-Liang Leon
    Wu, Chang-Fu
    Kan, Haidong
    Yi, Seung-Muk
    de Sousa Zanotti Stagliorio Coelh, Micheline
    Saldiva, Paulo Hilario Nascimento
    Honda, Yasushi
    Kim, Ho
    Armstrong, Ben
    Mortality risk attributable to high and low ambient temperature: a multicountry observational study2015In: The Lancet, ISSN 0140-6736, E-ISSN 1474-547X, Vol. 386, no 9991, p. 369-375Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Although studies have provided estimates of premature deaths attributable to either heat or cold in selected countries, none has so far offered a systematic assessment across the whole temperature range in populations exposed to different climates. We aimed to quantify the total mortality burden attributable to non-optimum ambient temperature, and the relative contributions from heat and cold and from moderate and extreme temperatures.

    METHODS: We collected data for 384 locations in Australia, Brazil, Canada, China, Italy, Japan, South Korea, Spain, Sweden, Taiwan, Thailand, UK, and USA. We fitted a standard time-series Poisson model for each location, controlling for trends and day of the week. We estimated temperature-mortality associations with a distributed lag non-linear model with 21 days of lag, and then pooled them in a multivariate metaregression that included country indicators and temperature average and range. We calculated attributable deaths for heat and cold, defined as temperatures above and below the optimum temperature, which corresponded to the point of minimum mortality, and for moderate and extreme temperatures, defined using cutoffs at the 2·5th and 97·5th temperature percentiles.

    FINDINGS: We analysed 74 225 200 deaths in various periods between 1985 and 2012. In total, 7·71% (95% empirical CI 7·43-7·91) of mortality was attributable to non-optimum temperature in the selected countries within the study period, with substantial differences between countries, ranging from 3·37% (3·06 to 3·63) in Thailand to 11·00% (9·29 to 12·47) in China. The temperature percentile of minimum mortality varied from roughly the 60th percentile in tropical areas to about the 80-90th percentile in temperate regions. More temperature-attributable deaths were caused by cold (7·29%, 7·02-7·49) than by heat (0·42%, 0·39-0·44). Extreme cold and hot temperatures were responsible for 0·86% (0·84-0·87) of total mortality.

    INTERPRETATION: Most of the temperature-related mortality burden was attributable to the contribution of cold. The effect of days of extreme temperature was substantially less than that attributable to milder but non-optimum weather. This evidence has important implications for the planning of public-health interventions to minimise the health consequences of adverse temperatures, and for predictions of future effect in climate-change scenarios.

    FUNDING: UK Medical Research Council.

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  • 31. Giang, Pham Ngan
    et al.
    Dung, Do Van
    Bao Giang, Kim
    Vinhc, Hac Van
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    The effect of temperature on cardiovascular disease hospital admissions among elderly people in Thai Nguyen Province, Vietnam2014In: Global Health Action, ISSN 1654-9716, E-ISSN 1654-9880, Vol. 7, article id 23649Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Projected increases in weather variability due to climate change will have severe consequences on human health, increasing mortality, and disease rates. Among these, cardiovascular diseases (CVD), highly prevalent among the elderly, have been shown to be sensitive to extreme temperatures and heat waves. OBJECTIVES: This study aimed to find out the relationship between daily temperature (and other weather parameters) and daily CVD hospital admissions among the elderly population in Thai Nguyen province, a northern province of Vietnam. METHODS: Retrospective data of CVD cases were obtained from a data base of four hospitals in Thai Nguyen province for a period of 5 years from 2008 to 2012. CVD hospital admissions were aggregated by day and merged with daily weather data from this period. Distributed lag non-linear model (DLNM) was used to derive specific estimates of the effect of weather parameters on CVD hospital admissions of up to 30 days, adjusted for time trends using b-splines, day of the week, and public holidays. RESULTS: This study shows that the average point of minimum CVD admissions was at 26°C. Above and below this threshold, the cumulative CVD admission risk over 30 lag days tended to increase with both lower and higher temperatures. The cold effect was found to occur 4-15 days following exposure, peaking at a week's delay. The cumulative effect of cold exposure on CVD admissions was statistically significant with a relative risk of 1.12 (95% confidence interval: 1.01-1.25) for 1°C decrease below the threshold. The cumulative effect of hot temperature on CVD admissions was found to be non-significant and was estimated to be at a relative risk of 1.17 (95% confidence interval: 0.90-1.52) for 1°C increase in the temperature. No significant association was found between CVD admissions and the other weather variables. CONCLUSION: Exposure to cold temperature is associated with increasing CVD admission risk among the elderly population.

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  • 32.
    Hassan, Osama Ahmed
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Public Health Institute, Khartoum, Sudan.
    Affognon, Hippolyte
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Mburu, Peter
    Sang, Rosemary
    Ahlm, Clas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Infectious Diseases.
    Evander, Magnus
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    The One Health approach to identify knowledge, attitudes and practices that affect community involvement in the control of Rift Valley fever outbreaks2017In: PLoS Neglected Tropical Diseases, ISSN 1935-2727, E-ISSN 1935-2735, Vol. 11, no 2, article id e0005383Article in journal (Refereed)
    Abstract [en]

    Rift Valley fever (RVF) is a viral mosquito-borne disease with the potential for global expansion, causes hemorrhagic fever, and has a high case fatality rate in young animals and in humans. Using a cross-sectional community-based study design, we investigated the knowledge, attitudes and practices of people living in small village in Sudan with respect to RVF outbreaks. A special One Health questionnaire was developed to compile data from 235 heads of household concerning their knowledge, attitudes, and practices with regard to controlling RVF. Although the 2007 RVF outbreak in Sudan had negatively affected the participants' food availability and livestock income, the participants did not fully understand how to identify RVF symptoms and risk factors for both humans and livestock. For example, the participants mistakenly believed that avoiding livestock that had suffered spontaneous abortions was the least important risk factor for RVF. Although the majority noticed an increase in mosquito population during the 2007 RVF outbreak, few used impregnated bed nets as preventive measures. The community was reluctant to notify the authorities about RVF suspicion in livestock, a sentinel for human RVF infection. Almost all the respondents stressed that they would not receive any compensation for their dead livestock if they notified the authorities. In addition, the participants believed that controlling RVF outbreaks was mainly the responsibility of human health authorities rather than veterinary authorities. The majority of the participants were aware that RVF could spread from one region to another within the country. Participants received most their information about RVF from social networks and the mass media, rather than the health system or veterinarians. Because the perceived role of the community in controlling RVF was fragmented, the probability of RVF spread increased.

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  • 33.
    Hii, Yien Ling
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Ng, Nawi
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Ng, Lee Ching
    Environmental Health Institute, National Environment Agency, Singapore.
    Zhu, Huaiping
    Department of Mathematics & Statistics, York University, Toronto, Canada.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Dengue risk index as an early warning2013Manuscript (preprint) (Other academic)
    Abstract [en]

    Introduction: A dengue early warning forewarns stakeholders and promotes timely prevention. Besides accuracy and timeliness, an effective early warning system must be comprised of a structure that allows clear and comprehensible communications to stakeholders, and facilitates planning of actions that corroborate with risks.  To aid such communication and planning efforts, this study established a risk-stratified forecast strategy which relies on uniformly interpreted risk indices derived from forecasted dengue cases.      

    Methodologies & Findings: We adopted the Poisson forecasting model developed by Hii et al. (2012) as model-1 and established a model-2 that considered only temperature and rainfall. We validate and compared the models for their forecast precision and sensitivity to diagnose outbreak and non-outbreak. Models were trained using data from 2001-2010. Forecast precision for the period 2011-2012 was analyzed using six cross-validations of 16-weeks forecast and root mean square errors. Operating Characteristic curve was used to analyze sensitivity of models. Forecasts were then translated into dengue risk indices according to estimated alert and epidemic thresholds. 

    Results showed that model-1 and model-2 explained about 84% and 70% of variance in dengue distribution, respectively. Average RMSE was 28 for model-1 and 33 for model-2 during cross-validations. ROC area was 0.96 (CI=0.93-0.98) for model-1 and 0.92 (CI=0.88-0.96) for model-2 in 2004-2010. The two models were able to forecast outbreak about 90% accuracy with around 10% false positive in 2011-2012.  Monthly and seasonal calendar risk index and weekly time series risk index were established using color scheme to represent risk levels.     

    Significance: Translation of a forecast to dengue risk index permits rapid and clear interpretation of forecast; thus enhances the effectiveness of an early warning. Further studies on feasibility of developing an automated forecast-control-calibration-system using different forecasting methods to allow parallel forecast for comparison and monitoring will enhance sustainability of forecast precision.

  • 34.
    Hii, Yien Ling
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Ng, Nawi
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Short term effects of weather on hand, foot and mouth disease2011In: PLOS ONE, E-ISSN 1932-6203, Vol. 6, no 2, p. e16796-Article in journal (Refereed)
    Abstract [en]

    Background: Hand, foot, and mouth disease (HFMD) outbreaks leading to clinical and fatal complications have increased since late 1990s; especially in the Asia Pacific Region. Outbreaks of HFMD peaks in the warmer season of the year, but the underlying factors for this annual pattern and the reasons to the recent upsurge trend have not yet been established. This study analyzed the effect of short-term changes in weather on the incidence of HFMD in Singapore.

    Methods: The relative risks between weekly HFMD cases and temperature and rainfall were estimated for the period 20012008 using time series Poisson regression models allowing for over-dispersion. Smoothing was used to allow non-linear relationship between weather and weekly HFMD cases, and to adjust for seasonality and long-term time trend. Additionally, autocorrelation was controlled and weather was allowed to have a lagged effect on HFMD incidence up to 2 weeks.

    Results: Weekly temperature and rainfall showed statistically significant association with HFMD incidence at time lag of 1-2 weeks. Every 1 degrees C increases in maximum temperature above 32 degrees C elevated the risk of HFMD incidence by 36% (95% CI = 1.341-1.389). Simultaneously, one mm increase of weekly cumulative rainfall below 75 mm increased the risk of HFMD by 0.3% (CI = 1.002-1.003). While above 75 mm the effect was opposite and each mm increases of rainfall decreased the incidence by 0.5% (CI = 0.995-0.996). We also found that a difference between minimum and maximum temperature greater than 7 degrees C elevated the risk of HFMD by 41% (CI = 1.388-1.439).

    Conclusion: Our findings suggest a strong association between HFMD and weather. However, the exact reason for the association is yet to be studied. Information on maximum temperature above 32 degrees C and moderate rainfall precede HFMD incidence could help to control and curb the up-surging trend of HFMD.

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  • 35.
    Hii, Yien Ling
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Rocklöv, Joacim
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Ng, Nawi
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Tang, Choon Siang
    Environment Health Department, National Environment Agency, Singapore.
    Pang, Fung Yin
    Environment Health Department, National Environment Agency, Singapore.
    Sauerborn, Rainer
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Climate variability and increase in intensity and magnitude of dengue incidence in Singapore2009In: Global Health Action, ISSN 1654-9716, E-ISSN 1654-9880, Vol. 2, p. 124-132Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION: Dengue is currently a major public health burden in Asia Pacific Region. This study aims to establish an association between dengue incidence, mean temperature and precipitation, and further discuss how weather predictors influence the increase in intensity and magnitude of dengue in Singapore during the period 2000-2007.

    MATERIALS AND METHODS: Weekly dengue incidence data, daily mean temperature and precipitation and the midyear population data in Singapore during 2000-2007 were retrieved and analysed. We employed a time series Poisson regression model includi