Health in a changing climate
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Image © John McConnico
After detailed investigation, the illness was found to be Chikungunya, an insect-born virus transmitted to humans by the Aedes or 'tiger' mosquito more common in Africa and Asia. The source of the infection was traced to a man holidaying in the region.
It is believed that the sick man was infected before travelling to Europe but was bitten by a tiger mosquito in Italy. The tiger mosquito is a vector or carrier of the virus and the insect in question is believed to have spread the virus to another person in the village. This set off a chain reaction, with tiger mosquitoes biting infected people and spreading the virus until a mini-epidemic developed.
A web of interactions
The outbreak of Chikungunya depended on an intricate web of interactions and conditions that reveal some of the health risks and challenges we face in a globalised world. Tourism, climate change, trade, movement of species and public health all played a part in the situation.
The tiger mosquito is believed to have been introduced to Europe via a range of imported goods — from ornamental plants such as 'lucky bamboo' to used tyres. The mosquito larva has been found in many parts of Europe but only survives outdoors in warmer, southern countries or in greenhouses further north — in the Netherlands, for example.
Dengue and West Nile Fever are also now found in Europe and are also transmitted by mosquito bites. According to the European Centre for Disease Prevention and Control (ECDC) in Stockholm, Sweden, since the first large outbreak in Romania in 1996, West Nile Fever infection has become recognised as a major cause of public health concern in Europe. No vaccine is currently available and the main preventive measures are aimed at reducing exposure to mosquito bites.
Intensive food production
We may be creating the conditions necessary for the spread of infectious disease — conditions that didn't exist before. The industrialisation of food production, for example, is a cause for major concern.
By intensively breeding one type of animal, we risk producing 'monocultures' with little genetic variability. These animals are very susceptible to diseases created by poor hygiene or infection from wild animals, such as birds. Once inside the monoculture, the diseases can easily mutate and spread even to the people working with the animals in question. Overuse of antibiotics has become an accepted method of compensating for the lack of natural resistance — a practice that could cause its own problems.
'Modern efficient agriculture, just like public health, looks to science and medicine to meet some of the demands of a globalised world. Although modern agriculture has benefited many of us with cheaper and plentiful food supplies it can also lead to unforeseen pressures and problems,' says Dr Marc Sprenger, Director of the ECDC.
'For example, as a result of the extensive use of antibiotics in agriculture, their effectiveness may decrease as bacteria become more resistant, which can potentially have an impact on humans too,' Dr Sprenger says.
Innovation: environment and health
Efforts to fight climate change will improve air quality
The European Union's Climate and Renewable Energy (CARE) package aims to:
• reduce greenhouse gas emissions by 20 % by 2020
• increase the share of renewable energy by 20 % by 2020
• improve energy efficiency by 20 % by 2020.
The efforts required to meet these targets will also cut air pollution in Europe. For example, improvements in energy efficiency and increased use of renewable energy will both lead to reduced fossil fuel combustion — a key source of air pollution. These positive side effects are referred to as the 'co-benefits' of climate change policy.
It has been estimated that the above package will cut the annual cost of meeting EU air pollution targets by billions of euros. And the savings to the European health services could be as much as six times greater.
Joining up the dots in Europe
New species and new diseases arriving in Europe are just some of the health impacts of climate change. Many more environmental and social impacts may ultimately affect human health through changes in the quality and quantity of water, air and food, and altered weather patterns, ecosystems, agriculture and livelihoods.
Climate change may also exacerbate existing environmental problems, such as air pollution, and disrupt sustainable water supplies and sanitation services.
The heat wave in Europe in summer 2003, with a death toll exceeding 70 000, highlighted the need for adaptation to a changing climate. The elderly and people with particular diseases are at higher risk, and deprived population groups are more vulnerable. In congested urban areas with high soil sealing and heat absorbing surfaces, the effects of heat waves can be exacerbated due to insufficient cooling at night and poor air flows.
For populations in the EU, mortality has been estimated to increase by 1–4 % for each degree increase of temperature above a (locally specific) cut-off point. In the 2020s, the estimated increase in heat-related mortality resulting from projected climate change could exceed 25 000 per year, mainly in central and southern European regions.
The discussion connecting health, land use, agriculture, tourism, trade and climate change needs to develop in an imaginative way. We may not be connecting public health and environment or climate change appropriately right now,' Dr Sprenger says.
'For example, I recently visited a department of health and asked who was in charge of climate-change-related issues and was told no one was. This is not passing judgement on any particular department or authority but it does illustrate that we need to change the way we think about these problems as they are all connected,' Dr Sprenger says.
'Public health systems must begin to adapt and open up to the possibility of new disease and new climate conditions. People may be misdiagnosed at the moment because their doctor is not familiar with a new virus. Many look and feel like flu. We need new tools to deal with the new challenges such as training, and facilities such as laboratories have to be flexible and adaptable,' he says.
- Visit the website of the ECDC: www.ecdc.europa.eu
- For more information and a full list of references, refer to the SOER 2010 Synthesis.
- For a full interview with Dr Sprenger, visit the Signals website: www.eea.europa.eu/signals
The Asian tiger mosquito or Aedes albopictus is one of the most widespread examples of an 'invasive species'. Its traditional range is from Pakistan to North Korea. It is now found all over the world and has been described as the 'most invasive mosquito in the world'.
The mosquito is just one example of a much wider threat to Europe's biodiversity as alien or non-native species establish and spread across the continent as a result of human activities. Alien species can be found in all European ecosystems. Globalisation, particularly increased trade and tourism, has resulted in an upsurge in the number and type of alien species arriving in Europe.
About 10 000 alien species have been registered in Europe. Some, such as the potato and the tomato, were introduced on purpose and remain economically important to this day. Other species, called 'invasive alien species', can create serious problems to gardening, agriculture and forestry, as vectors of diseases or by damaging constructions such as buildings and dams.
Invasive alien species also change the ecosystems they live in and affect the other species in those ecosystems. The UN Convention on Biological Diversity identifies invasive alien species as one of the major threats to biodiversity worldwide.