Culicid Mosquitoes as Vectors of Disease Agents in Europe

The chikungunya fever epidemic in northern Italy in 2007 and the recent demonstration of the introduction of various exotic mosquito species alerted the European nations to a growing risk of invasion by vector mosquitoes and outbreaks of mosquito-borne infectious diseases. The importation of both mosquitoes and pathogens they are able to transmit is facilitated by increasing international trade and travel. Environmental and climatic changes do not only set the ground for the establishment of invasive mosquitoes away from their natural distribution areas but often also have beneficial effects on indigenous potential vector species, such as support of spread, growth in population density and extension of seasonal activity, thus increasing the probability of these biting a person or a reservoir animal infected with a mosquito-borne pathogen and transmitting it. While there is a considerable body of literature on invasive mosquito species and imported pathogens due to their relevance in their natural distribution areas, data on endemic mosquito species and mosquito-borne pathogens circulating in Europe are relatively scarce. With a few exceptions, these have in fact for several decades been of minor importance with respect to public health impact. Both the role of mosquitoes as vectors of disease agents and the scientific and political attention to mosquito-borne diseases, however, appear to be growing in Europe with ongoing globalization. We here discuss indigenous mosquito species that have historically been involved in pathogen transmission in Europe or have been demonstrated to be vectors elsewhere and that may contribute to future disease outbreaks in Europe. Likewise, we present mosquito-borne pathogens that have been circulating in Europe or are considered probable to be introduced and established in the future.