Climate change in Europe
Accelerating economic activity and fossil fuel combustion over the last century have precipitated an environmental impact of unprecedented proportions. Ecosystem decline, loss of biodiversity, stratospheric ozone depletion, and climate change are some of these environmental changes. Climate change is ascribed to natural processes and human activity altering atmospheric conditions. Climate change is indeed tangible: the worldwide mean surface temperature has increased by 0.74±0.18°C over the past 100 years , while the worldwide sea level has risen by 1.8 mm per year since 1961 and the Arctic sea ice is retreating by 2.7±0.6% per decade. In addition, sea surface temperatures are warming, mountain glaciers are shrinking, oceans are becoming more acidic, extreme weather events are increasing in frequency and intensity. These climatic changes have already had noticeable effects on many natural systems, including marine and terrestrial ecosystems, such as the timing of seasonal biological events and the distribution of animal and plant species.
The transmission of infectious disease is determined by many factors including social, economical, ecological conditions, access to care and intrinsic human immunity. Many infectious agents, vector organisms, non-human reservoir species, and pathogen replication rates are particularly sensitive to climatic conditions. Numerous theories have been developed in recent years to explain the relationship between climate change and infectious diseases: they include higher proliferation rates at higher temperatures, extended transmission season, changes in ecological balances, and climate-related migration of vectors, reservoir hosts, or human populations.
The relationship between climate change and infectious diseases in Europe thus call for careful assessment and analysis.
In this Review we look at the evidence for climate-related changes in infectious disease incidence, distribution, localised outbreaks, and potential for the establishment of tropical vector species in Europe. Based on this review, ECDC has identified the need to tackle the technical challenges by developing a blueprint for an environmental and epidemiological network that would link existing resources. Merging, integrating, and analysing such data will advance our understanding of the relationship between climate change and infectious diseases in Europe and inform public health action, summarized.
Source: Semenza JC, Menne B. Climate Change and Infectious Diseases in Europe. Lancet ID. 2009;9:365-75.
Figure 1. Key European vulnerabilities to climate change (biogeographical regions)
Key vulnerabilities of European systems and sectors to climate change during the 21st century for the main biogeographic regions of Europe (EEA, 2004a): TU: Tundra, pale turquoise. BO: Boreal, dark blue. AT: Atlantic, light blue. CE: Central, green; includes the Pannonian Region. MT: Mountains, purple. ME: Mediterranean, orange; includes the Black Sea region. ST: Steppe, cream. SLR: sea-level rise. NAO:
North Atlantic Oscillation. Copyright EEA, Copenhagen. http://www.eea.europa.eu
Climate change and public health
The impact on public health from climate change may be far reaching and include deaths and hospitalizations due to heat waves; hypothermia from blizzards; injuries and death from flooding; and potential shifts in the transmission ranges of vector-borne diseases such as hantavirus, West Nile virus, tick-borne encephalitis, Lyme disease, Malaria and Dengue. Most importantly, the potential population health impacts of environmental changes extend far into future, if environmental conditions deteriorate further. Change can be abrupt and unexpected but they can also be protracted and gradual and thus pose considerable challenges to public health.
Climate change and communicable diseases
Climate change may also alter the distribution and transmission of communicable diseases principally through impacting disease pathogens directly; through impacting the distribution of vectors which may carry diseases; or through impacting human behaviours leading to changing patterns of exposure to infectious diseases (e.g. increased time spent outdoors in woodlands where ticks live).
Vector-borne diseases are transmitted by arthropods such as ticks (e.g. tick-borne encephalitis (TBE), Lyme disease), mosquitoes (e.g. Chikungunya fever, Dengue fever), or sandflies (e.g. visceral leishmaniasis). Climatic changes, such as hotter and longer summers, warmer winters, and/or increased annual rainfalls could enable these organisms to shift their habitats, potentially introducing diseases to areas previously unfamiliar with them.
Meanwhile, food-borne diseases like salmonellosis have been observed to be highly temperature sensitive, meaning that increased annual average temperatures could have important effects on food safety. Climate change may influence water quality and availability (drinking and bathing) while also leading to increased risks of flooding in some regions. Thus water-borne diseases , such as those caused by Cryptosporidium in drinking water and Vibrio bacteria in bathing water, need to be further examined for their potential links to climate change, along with air-borne diseases and rodent-borne diseases .
For each of the above examples, it is important to point out that our current understandings contain elements of uncertainty. Climate change is one of many important factors driving infectious disease spread, alongside human and animal population dynamics, intense global levels of trade and travel, changing patterns of land use, and so on. Thus one important area of ECDC activity is to further quantify and examine the links between climate change and other determinants of communicable diseases.
European Environment and Epidemiology Network (E3): 21st Century Surveillance
The pan-European capacity to analyse, predict and respond to changing communicable disease patterns due to global change is currently underdeveloped. Despite the abundance of environmental and epidemiologic data, they are often not linked, thereby preventing public health and environmental agencies and scientists from gaining more comprehensive understandings of the multi-causal pathways that drive environmental and epidemiological change.
To address this shortcoming ECDC is exploring the development of the European Environment and Epidemiology Network (E3) that could link climatic/environmental and infectious disease data in order to strengthen European capacity in forecasting, monitoring and responding to the threats posed by new and emerging diseases.
The E3 network would connect epidemic intelligence and infectious disease surveillance data (currently housed at ECDC) with meteorological variables, entomological data, water quality records, air quality measures, remote sensing information, geology, population density and many other information sources. Through integrating and synthesizing these data sets, disease surveillance systems would be able to incorporate and analyse environmental precursors to disease pandemics, thus preparing public health to meet the challenges of our time.