Outbreaks of vector-borne diseases are likely to become more frequent in Europe in the future, the European Centre for Disease Prevention and Control (ECDC) warns. According to an ECDC-initiated assessment, climate and environmental changes in the form of rising temperatures and humidity as well as globalisation promote the spread of the vectors or intermediate hosts and ultimately the spread of the disease itself. In epidemiology, the term 'vector' is used to refer to organisms that do not cause a particular disease themselves, but still pass it on from host to host. The vector, as the pathogen's intermediate host, is not affected and the disease only breaks out in the definitive host. Vector-borne diseases include Dengue Fever, West Nile Virus, Chikungunya fever, nephropathia epidemica and tick-borne encephalitis (TBE), which make their way to their human hosts through mosquitoes, sand-flies, ticks and rodents. 'The climate and environmental changes being predicted by experts will alter the risk to Europe from vector-borne diseases,' says Dr Zsuzsanna Jakab, director of the ECDC. 'We are likely to see the spread of diseases such as tick-borne encephalitis, or even Chikungunya fever, to places where they have not been seen before. 'It's not just environmental factors,' Dr Jakab adds. 'Globalisation, and the increased travel and trade that it brings, is also quickening the pace at which diseases can spread to new areas.' The increased risk is illustrated by an outbreak of Chikungunya fever in the area of Ravenna on the North-Eastern coast of Italy in summer 2007. Nearly 250 people were infected when a traveller from India carrying the Chikungunya virus was bitten by an Aedes Albopictus or Asian Tiger Mosquito. The Asian Tiger Mosquito has spread across large parts of Asia, Africa and the Americas as well as some parts of Europe in recent decades. It is a known vector of Chikungunya fever. Although the Chikungunya virus is normally not fatal, it causes a high fever, severe joint pain, muscle pain and headaches and may result in serious complications and chronic conditions in some patients. While increased temperatures and humidity facilitate the spread of vectors such as mosquitoes, the Asian Tiger Mosquito is known to be introduced to Europe by the used tyre industry, as used tyres provide a good breeding ground for mosquitoes. Another disease that has been on the rise in recent years is TBE, a virus that infects the central nervous system and is spread by ticks. The number of infections with TBE in some areas of Europe where the disease is endemic has increased by nearly 400% over the past 30 years, making TBE a major public health challenge. Dr Jakab summarises: 'We need to better understand how theses changes will alter the risk of vector-borne diseases to better target surveillance and control, and improve preparedness in European countries.'