Climate services for health: cooperation for climate informed dengue surveillance
Authors: Elvina Viennet, David Harley
Journal: The Lancet Planetary Health (2017)

Threats to human health consequent upon global environmental change (eg, climate change, stratospheric ozone depletion, loss of biodiversity, nitrogen loading, and persistent organic pollutants) are increasing.1Martens WJM McMichael AJ Environmental change, climate, and health: issues and research methods. Cambridge University Press, Cambridge, NY2002Crossref Google Scholar Climate change is partly attributable to anthropogenic emissions of greenhouse gases.2McMichael AJ Woodruff RE Hales S Climate change and human health: present and future risks.Lancet. 2006; 367: 859-869Summary Full Text Full Text PDF PubMed Scopus (1696) Google Scholar Extreme weather events and short-term variations in climatic conditions have direct effects on human health, such as heat-related deaths, physical injury, and mental health effects.3Hales S Edwards SJ Kovats RS Chapter 5. Impacts on health of climate extremes. World Health Organization, Geneva2003Google Scholar, 4Berry HL Bowen K Kjellstrom T Climate change and mental health: a causal pathways framework.Int J Public Health. 2010; 55: 123-132Crossref PubMed Scopus (433) Google Scholar Lifecycles of water, food, and vector-borne pathogens are also affected by climatic factors via ecological and biological processes.5Confalonieri U Menne B Akhtar R et al.Human health. Climate change 2007: impacts, adaptation and vulnerability. Cambridge University Press, Cambridge, UK2007Google Scholar Despite an increase, there is still little collaboration between the health and meteorological sectors to assist risk management decisions.6WHOWorld Meteorological OrganizationClimate services for health: improving public health decision-making in a new climate. World Health Organization, Geneva2016Google Scholar Climate services for health is an emerging discipline with an objective to help health professionals better understand the effect of climate and weather conditions on health, and ultimately, to anticipate disease risk consequent upon climate change. Eventually, this holistic process will enable targeting of interventions for more efficient and effective prevention and treatment to reduce risk of disease transmission. In The Lancet Planetary Health, Rachel Lowe and colleagues7Lowe R Stewart Ibarra AM Petrova D et al.Climate services for health: predicting the evolution of the 2016 dengue season in Machala, Ecuador.Lancet Planet Health. 2017; 1: e142-e152Summary Full Text Full Text PDF Scopus (65) Google Scholar show the potential of application of climate services for health to dengue in the city of Machala, El Oro Province, Ecuador, where dengue is hyperendemic and transmitted throughout the year with co-circulation of all four dengue serotypes. Machala is an ideal site for analysis of dengue transmission mechanisms, in view of the high vector indices and volume of people and goods moving across the Ecuador–Peru border.8Stewart-Ibarra AM Munoz AG Ryan SJ et al.Spatiotemporal clustering, climate periodicity, and social-ecological risk factors for dengue during an outbreak in Machala, Ecuador, in 2010.BMC Infect Dis. 2014; 14: 610Crossref PubMed Scopus (75) Google Scholar Monthly dengue incidence was predicted from January to November, 2016, using a seasonal climate forecast of precipitation and minimum temperature and El Niño forecast in a Bayesian statistical model framework. The estimated dengue incidence was then compared with active surveillance data. The collation of spatiotemporal climatic data with epidemiological, clinical, and environmental data is a powerful approach to understanding associations between health outcome and climate exposure. Although climate data has been used to formulate disease models and produce predictions, Lowe and her colleagues7Lowe R Stewart Ibarra AM Petrova D et al.Climate services for health: predicting the evolution of the 2016 dengue season in Machala, Ecuador.Lancet Planet Health. 2017; 1: e142-e152Summary Full Text Full Text PDF Scopus (65) Google Scholar present the first study to use active surveillance data to account for misreporting of other diseases (chikungunya in this study) as dengue to improve the model. The great strengths of the study are the use of real-time climate forecasts to make long-lead dengue predictions and the use of active surveillance data. The practical benefit is the demonstration that the use of seasonal climate and El Niño forecasts allows a prediction to be made at the start of the year for the entire dengue season. While the Ecuadorian Ministry of Health, which is the institution responsible for dengue control,9Heydari N Larsen AD Neira M et al.Household dengue prevention interventions, expenditures, and barriers to Aedes aegypti control in Machala, Ecuador.Int J Environ Res Public Health. 2017; 14: 2Crossref Scopus (35) Google Scholar informally monitors dengue incidence based on historical passive surveillance data averaged over the previous 5 years, Lowe and colleagues7Lowe R Stewart Ibarra AM Petrova D et al.Climate services for health: predicting the evolution of the 2016 dengue season in Machala, Ecuador.Lancet Planet Health. 2017; 1: e142-e152Summary Full Text Full Text PDF Scopus (65) Google Scholar provide a method for advanced warning of the timing and magnitude of peak dengue incidence. This work confirms that the health community in Ecuador needs climate services to anticipate dengue transmission. The predictions by Lowe and colleagues,7Lowe R Stewart Ibarra AM Petrova D et al.Climate services for health: predicting the evolution of the 2016 dengue season in Machala, Ecuador.Lancet Planet Health. 2017; 1: e142-e152Summary Full Text Full Text PDF Scopus (65) Google Scholar if reproducible, represent an opportunity for the authorities to (1) increase resources for health surveillance, vector control, and prevention (eg, seasonal increase in personnel, community participation, sustainable access to piped water), (2) improve the diagnosis of clinical cases and laboratory confirmation of cases to avoid misreporting, and (3) increase reporting speed. Understanding how climate variability and long-term climate change affect transmission of dengue and other vector-borne diseases is an ongoing challenge. Climate services synthesise input from multiple disciplines and hence encourage innovative thinking to reduce uncertainty in projections. Lowe and colleagues7Lowe R Stewart Ibarra AM Petrova D et al.Climate services for health: predicting the evolution of the 2016 dengue season in Machala, Ecuador.Lancet Planet Health. 2017; 1: e142-e152Summary Full Text Full Text PDF Scopus (65) Google Scholar present a case study, showing a way forward for the discipline of climate services. They contend that seasonal climate forecasting is more accurate during El Niño and La Niña events. However, how real-time climate forecasts would perform in the absence of a long El Niño season remains unclear. In some years, other factors will have a more powerful effect on dengue incidence than seasonal climate factors (eg, efficiency of vector control programmes, population immunity status, patterns of human settlement, movement from neighbouring endemic regions, population growth and density, socioeconomic factors, absence of community engagement, budget cuts in health).10Viennet E Ritchie SA Williams CR Faddy HM Harley D Public health responses to and challenges for the control of dengue transmission in high-income countries: four case studies.PLoS Negl Trop Dis. 2016; 10: e0004943Crossref Scopus (26) Google Scholar Such information, nevertheless, is challenging to obtain with a sufficient degree of quality, reliability, suitability, and at the appropriate spatiotemporal scale, especially in resource-limited settings. The aforementioned factors are not accounted for in the model, but including yearly random effects is a suitable way to quantify interannual variability in dengue risk resulting from unmeasured factors. Further work using improved seasonal climate forecasts is needed to confirm the potential value of incorporating climate information into health decision instruments. These methods must be generalised and translated into a public health decision-making instrument for health authorities to reduce the burden of climate-sensitive diseases, and to work to optimise quality and quantity of spatiotemporal data to deliver the best possible early warning systems for climate-affected diseases. EV declares no competing interests. DH is a financial member of Doctors for the Environment, Australia, and am a member of the Royal Australasian College of Physicians reference group on climate change and health. Climate services for health: predicting the evolution of the 2016 dengue season in Machala, EcuadorThis dengue prediction framework, which uses seasonal climate and El Niño forecasts, allows a prediction to be made at the start of the year for the entire dengue season. Combining active surveillance data with routine dengue reports improved not only model fit and performance, but also the accuracy of benchmark estimates based on historical seasonal averages. This study advances the state-of-the-art of climate services for the health sector, by showing the potential value of incorporating climate information in the public health decision-making process in Ecuador. Full-Text PDF Open Access