Ecology of West Nile Fever across four European countries: Review of weather profiles, vector population dynamics and vector control response

Authors: CHASKOPOULOU, ALEXANDRA - EUROPEAN BIOLOGICAL CONTROL LABORATORY (EBCL); L'AMBERT, GREGORY - EID-MEDITERRANEAN; PETRIC, DUSAN - UNIVERSITY OF NOVI SAD; BELLINI, ROMEO - CAA G NICOLI; ZGOMBA, MARIJIA - UNIVERSITY OF NOVI SAD; GROEN, THOMAS - UNIVERSITY OF TWENTE; MARRAMA, LAURENCE - EUROPEAN CENTRE FOR DISEASE CONTROL AND PREVENTION; BICOUT, DOMINIQUE - VETAGRO SUP

Submitted to: Parasites & Vectors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2016
Publication Date: 9/1/2016
Citation: Chaskopoulou, A., L'Ambert, G., Petric, D., Bellini, R., Zgomba, M., Groen, T.A., Marrama, L., Bicout, D.J. 2016. Ecology of West Nile Fever across four European countries: Review of weather profiles, vector population dynamics and vector control response. Parasites & Vectors. 9(1): 482. DOI: 10.1186/s13071-016-1736-6.

Interpretive Summary: West Nile virus (WNV) represents a serious burden to human and animal health because of its capacity to cause unforeseen and large epidemics. In nature the virus circulates in a sylvatic/rural cycle, between birds and ornithophilic mosquitoes particularly members of the genus Culex, and under certain environmental conditions it spills over to human settlements where it infects humans and equines causing large epidemics. Precipitation, temperature and landscape use/management are among the most important environmental parameters that influence the life-cycles of the mosquito, the virus, the amplifying and accidental hosts and the interactions between them. Because of these features, outbreaks of WNV infection are highly sporadic and focal in nature exhibiting high variability in their development and incidence across different regions. Studies are needed at local levels that compare different habitats and mosquito/vertebrate communities to determine how environmental parameters influence vector population and disease transmission dynamics and how mosquito control interventions may alter these dynamics. This is the prelude to designing a modeling approach for appraising and comparing the impacts of different vector control strategies on the population dynamics of vector species involved in the transmission cycle of WNV. These models, after validation through field trials, will be made available for the public health professionals as a support tool to compare and assess the cost-efficacy of different control strategies against WNV. Complementary beneficiaries of this project are researchers and others that will have access to a practical tool validated in the field in collaboration with a set of different countries.

Technical Abstract: West Nile virus (WNV) represents a serious burden to human and animal health because of its capacity to cause large unforeseen epidemics. Until 2004, only lineage 1 and 3 WNV strains had been found in Europe. Lineage 2 strains were initially isolated in 2004 (Hungary), again in 2008 (Austria), and for the first time caused a major WNV epidemic in 2010 in Greece with 262 clinical human cases and 35 fatalities. Since then, WNV lineage 2 outbreaks have been reported in several European countries including Italy, Serbia and Greece. Understanding the interaction of ecological factors that affect WNV transmission is crucial for preventing or decreasing the impact of future epidemics. The synchronous co-occurrence of sufficient densities of competent mosquito vectors, virus, bird reservoir hosts, and susceptible humans is necessary for the initiation and propagation of an epidemic. Weather is the key abiotic factor influencing the life cycles of the mosquito vector, the virus, the reservoir hosts and the interactions between them. The purpose of this paper is to review and compare mosquito population dynamics, and weather conditions, in three ecologically different contexts (urban/semi-urban, rural/agricultural, natural) across four European countries (Italy, France, Serbia, Greece) with a history of WNV outbreaks. Local control strategies will be described as well. Improving our understanding of WNV ecology is a prerequisite step for appraising and optimizing vector control strategies in Europe with the ultimate goal to minimize the probability of WNV infection. This is the prelude to designing a modeling approach for appraising and comparing the impacts of different vector control strategies on the population dynamics of vector species involved in the transmission cycles of WNV.