EDENext

EDENext, Biology and control of vector-borne infections in Europe, is a Research project funded under the European Union’s Seventh Framework Programme dedicated to investigating the biological, ecological and epidemiological components of - particularly their introduction, emergence and spread - and the creation of new tools to control them. It was officially launched in March 2011 at a kick-off meeting in Budapest, Hungary, and brings together 46 international partners from 22 countries.
The challenges
Environmental and socio-economic changes mean that vector-borne diseases (VBD) are becoming an increasing challenge for human and veterinary public health not only in Europe, but across the globe. Emerging infectious diseases (EID) are often detected in Europe and North America but also pose major risks for developing countries, where many factors favour the emergence of VBD and there are limited health facilities to prevent, monitor or control their spread. EDENext therefore not only helps to protect and improve public health and the welfare of European citizens, but is part of a coordinated international effort.
Understanding diseases
EDENext seeks to understand and explain biological, ecological and epidemiological processes involved in vector-borne diseases to develop a set of state-of-the-art methods and tools to improve the prevention, surveillance and control of vector populations and VBD. The project is organised around a set of vector groups: , mosquitoes, Culicoides midges and sand flies. In addition, another group of researchers is studying rodent and insectivore-borne diseases. Strictly speaking, rodents are not vectors but mostly reservoirs, but the objectives of the rodents research group are the same as the vector groups. For brevity, all of these topics are often grouped together as VBDs.
Control and prevention
There are three clear strands in the control and prevention of vector-borne diseases. The first is an appreciation and understanding of the sequence of events which lead to vector-borne diseases: introduction, emergence and spread. Understanding each of these components is crucial in developing a science-based and data-driven suite of preventative, control or monitoring measures. The second is the control of vector populations and the ability to break epidemiological cycles, for which many different methods are available. The third strand concerns the need for relevant and accurate data on risk perception in the public health agencies and in the exposed human population, as well as a clear understanding of the importance of these human population segments.
Diseases under study
EDENext is focusing on particular diseases
, chosen because there is currently insufficient epidemiological knowledge or a lack of control measures for efficient intervention programmes. Also, these selected diseases have been categorised as priority diseases for European public health agencies in an expert study launched by the European Centre for Disease Prevention and Control.
Tick-borne diseases
Crimean-Congo haemorrhagic fever and newly emerging diseases, mainly transmitted by , e.g. human granulocytic anaplasmosis,caused by Anaplasma phagocytophilum. Other tick-transmitted infections of growing concern in the EU include those caused by the protozoan parasites Babesia microti and Babesia venatorum (EU 1) and those caused by rickettisae of the spotted fever group, such as R. helvetica. An assessment of their current distribution and potential spread is essential. Several other pathogens have been identified in Ixodes ricinus, such as Francisella tularensis and Bartonella spp., but the capacity for transmission by this tick species has to be evaluated. The occurrence, and possible spread of the taiga tick, I. persulcatus, in Finland and the Baltic states, possibly elsewhere, poses additional challenges because its ecological requirements differ from those of I. ricinus.
Rodent and insectivore-borne diseases
Hantavirus infections have a significant global and European public health impact. They are emerging infections (they are found in new areas) and their incidence has also increased in several established endemic regions. Recent work conducted under the EDEN project discovered new groups of potential zoonotic agents borne by rodents and other small mammals in Europe. Essential in understanding the epidemiologies due to rodent-borne pathogens is the ecological and population dynamical knowledge of the underlying causes of the geographic patterns of density variations of reservoir species.
Mosquito-borne diseases
West Nile virus (WNV), for which a lot of research is still needed to better understand its epidemiology and the risk of large-scale spread in Europe. Recent outbreaks in Italy and the emergence of WN virus lineage 2 in Hungary, Austria, Romania, and Greece have also raised public health concerns. The recent Chikungunya outbreak in Italy has revealed the epidemic potential of (and other invasive mosquito species such as Ae. japonicus) as a vector for Chikungunya virus and other arboviruses such as dengue.
Culicoides-borne diseases
These have been a central feature of veterinary epidemiology over the past decade, and continue to have major economic consequences. The spreading Bluetongue virus (BTV) in domestic and wild ruminants has been their most important impact so far, but other diseasess are lurking on Europe’s borders, including epizootic haemorrhagic disease in ruminants and African horse sickness and horse encephalosis. For years the northward spread of these diseases has been associated with the extension of the distribution of their main Afro-asiatic vector, . However, the emergence of several BTV serotypes in Northern Europe from 2006 has confirmed that endemic Culicoides species are able to transmit BTV efficiently and that overwintering mechanisms are able to maintain the virus in animal hosts and/or infected vectors.
Sand fly-borne diseases
The focus is on leishmaniasis and infections. Work conducted in the earlier EDEN project showed that sand fly distributions in Europe are changing. In parallel, increases in human and canine leishmaniasis infections, as well as a spread of human infections by Toscana Phlebovirus has been reported. Moreover, with the increased movement of people and animals due to migration and travel, together with environmental changes and other aspects of globalisation, there is an increased risk for the introduction and spread of infections by Leishmania species such as L. tropica or L. donovani in Europe and in the newly emerging Leishmania hybrids.
Public health and vector-borne diseases
Due to environmental and economic changes, emerging diseases with zoonotic potential will be an increasing challenge for public health in Europe. The risks and the consequences triggered by vector-borne diseases for public health in Europe are just starting to emerge in the public awareness. EDENext is following a holistic, transdisciplinary public health approach towards vector-borne diseases. Sensible risk communication will be developed, based on scientific risk assessment on one hand, and taking into account public risk perception on the other.
Of the numerous vector-pathogen pairings the project will be studying, particular emphasis will be placed on the public health aspects of two: hantaviruses, which cause haemorrhagic fever with renal syndrome (HFRS), transmitted by rodents, and nairovirus, which causes Crimean-Congo haemorrhagic fever (CCHF) caused by the homonymous virus, transmitted by ticks.
Organisation
EDENext brings together 46 partners from 22 countries. The coordinator is Renaud Lancelot, from CIRAD , a French research centre working with developing countries to tackle international agricultural and development issues. In March 2011 he said: “The project follows on from EDEN (2004-2010), which centred on the effects of environmental changes on the emergence of diseases transmitted by vectors (mosquitoes, ticks, etc.). EDENext intends to go further towards understanding the ecological and biological mechanisms that result in epidemics of such diseases. We will be placing strong emphasis on the social and economic factors that favour contamination, and controlling disease risk.”

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