Rift V alley fever ( RVF ) is a mosquito‐borne disease caused by the R ift V alley fever virus ( RVFV ). Rift V alley fever affects a large number of species, including human, and has severe impact on public health and the economy, especially in A frican countries. The present study examined the vector competence of three different E uropean mosquito species, Culex pipiens ( L innaeus, 1758) form molestus (Diptera: Culicidae), Culex pipiens hybrid form and Stegomyia albopicta (= Aedes albopictus ) ( S kuse, 1894) (Diptera: Culicidae). Mosquitoes were artificially fed with blood containing RVFV . Infection, disseminated infection and transmission efficiency were evaluated. This is the first study to assess the transmission efficiency of E uropean mosquito species using a virulent RVFV strain. The virus disseminated in Cx. pipiens hybrid form and in S. albopicta . Moreover, infectious viral particles were isolated from saliva of both species, showing their RVFV transmission capacity. The presence of competent Cx. pipiens and S. albopicta in S pain indicates that an autochthonous outbreak of RVF may occur if the virus is introduced. These findings provide information that will help health authorities to set up efficient entomological surveillance and RVFV vector control programmes.

Reported human cases of West Nile virus (WNV) in Europe increased dramatically in 2018. Lineage 1 strains had been circulating in Euro-Mediterranean countries since the early 1990s. The subsequent introduction of WNV lineage 2 has been responsible for the remarkable upsurge of European WNV outbreaks since 2004, including the dramatic increase in human cases observed since 2018. The virus exists in a natural cycle between mosquitoes and wild birds, with humans and horses acting as dead-end hosts. As the key vertebrate hosts in the transmission cycle of WNV, avian species have been the focus of surveillance across many countries. Raptors appear particularly susceptible to WNV infection, resulting in higher prevalence, and in some cases exhibiting neurological signs that lead to the death of the animal. In addition, birds of prey are known to play an important role as WNV reservoir and potentially amplifying hosts of infection. Importantly, raptor higher susceptibility/prevalence may indicate infection through predation of infected prey. Consequently, they are considered important target species when designing cost-effective surveillance for monitoring both seasonal WNV circulation in endemic countries and its emergence into new areas, where migrating raptors may play a critical role in virus introduction. This review summarizes the different aspects of the current knowledge of WNV infection in birds of prey and evaluates their role in the evolution of the epizootic that is spreading throughout Europe.

Eastern Europe (EE) has been severely affected by mosquito-borne viruses (moboviruses). In this review, we summarize the epidemiology of moboviruses, with particular attention to West Nile virus (WNV). The study of WNV human cases in EE between 2010 and 2016, revealed that the epidemiology of WNV in EE is complex with the combination of introduction of different WNV strains from lineages 1 and 2, and the establishment of endemic cycles. We found a positive correlation between the risk of WNV re-emergence in an area and the number of human cases reported in the previous year. We also report the main ecological and biological characteristics of the key mosquito species vectors of moboviruses. Recent expansion of invasive mosquito species in EE, mainly Aedes albopictus but also Aedes aegypti and Culex quinquefasciatus, may result in new scenarios with an increased risk of transmission of moboviruses. Main gaps of knowledge in relation to moboviruses and their vectors in EE are identified. Understanding the epidemiology of moboviruses in EE is essential for the improvement of their surveillance and the control of the diseases they cause.

Dengue has emerged as the most important viral mosquito-borne disease globally. The current risk of dengue outbreaks in Europe appeared with the introduction of the vector Aedes albopictus mosquito in Mediterranean countries. Considering the increasing frequency of dengue epidemics worldwide and the movement of viraemic hosts, it is expected that new autochthonous cases will occur in the future in Europe. Arbovirus surveillance started in Catalonia in 2015 to monitor imported cases and detect possible local arboviral transmission. During 2015, 131 patients with a recent travel history to endemic countries were tested for dengue virus (DENV) and 65 dengue cases were detected. Twenty-eight patients with a febrile illness were viraemic, as demonstrated by a positive real-time RT-PCR test for DENV in serum samples. Entomological investigations around the viraemic cases led to the detection of DENV in a pool of local Ae. albopictus captured in the residency of one case. The sequence of the DENV envelope gene detected in the mosquito pool was identical to that detected in the patient. Our results show how entomological surveillance conducted around viraemic travellers can be effective for early detection of DENV in mosquitoes and thus might help to prevent possible autochthonous transmission.

Background: Every year, more than 700,000 people die from vector-borne diseases, mainly transmitted by mosquitoes. Vector surveillance plays a major role in the control of these diseases and requires accurate and rapid taxonomical identification. New approaches to mosquito surveillance include the use of acoustic and optical sensors in combination with machine learning techniques to provide an automatic classification of mosquitoes based on their flight characteristics, including wingbeat frequency. The development and application of these methods could enable the remote monitoring of mosquito populations in the field, which could lead to significant improvements in vector surveillance. Methods: A novel optical sensor prototype coupled to a commercial mosquito trap was tested in laboratory conditions for the automatic classification of mosquitoes by genus and sex. Recordings of > 4300 laboratory-reared mosquitoes of Aedes and Culex genera were made using the sensor. The chosen genera include mosquito species that have a major impact on public health in many parts of the world. Five features were extracted from each recording to form balanced datasets and used for the training and evaluation of five different machine learning algorithms to achieve the best model for mosquito classification. Results: The best accuracy results achieved using machine learning were: 94.2% for genus classification, 99.4% for sex classification of Aedes, and 100% for sex classification of Culex. The best algorithms and features were deep neural network with spectrogram for genus classification and gradient boosting with Mel Frequency Cepstrum Coefficients among others for sex classification of either genus. Conclusions: To our knowledge, this is the first time that a sensor coupled to a standard mosquito suction trap has provided automatic classification of mosquito genus and sex with high accuracy using a large number of unique samples with class balance. This system represents an improvement of the state of the art in mosquito surveillance and encourages future use of the sensor for remote, real-time characterization of mosquito populations. Graphical

Rift Valley fever is a mosquito-borne zoonotic disease that affects domestic ruminants and humans. Culex flavivirus is an insect-specific flavivirus that naturally exists in field mosquito populations. The influence of Culex flavivirus on Rift Valley fever phlebovirus (RVFV) vector competence of Culex pipiens has not been investigated. Culex flavivirus infection in a Cx. pipiens colony was studied by Culex flavivirus oral feeding and intrathoracical inoculation. Similarly, vector competence of Cx. pipiens infected with Culex flavivirus was evaluated for RVFV. Infection, dissemination, transmission rates and transmission efficiency of Culex flavivirus-infected and non-infected Cx. pipiens artificially fed with RVFV infected blood were assessed. Culex flavivirus was able to infect Cx. pipiens after intrathoracically inoculation in Cx. pipiens mosquitos but not after Culex flavivirus oral feeding. Culex flavivirus did not affect RVFV infection, dissemination and transmission in Cx. pipiens mosquitoes. RVFV could be detected from saliva of both the Culex flavivirus-positive and negative Cx. pipiens females without significant differences. Moreover, RVFV did not interfere with the Culex flavivirus infection in Cx. pipiens mosquitoes. Culex flavivirus infected and non-infected Cx. pipiens transmit RVFV. Culex flavivirus existing in field-collected Cx. pipiens populations does not affect their vector competence for RVFV. Culex flavivirus may not be an efficient tool for RVFV control in mosquitoes.