Monitoring population and environmental parameters of invasive mosquito species in Europe

Vector competence of Swedish Culex pipiens mosquitoes for Japanese encephalitis virus

BACKGROUND

Japanese encephalitis virus (JEV) is an emerging mosquito-borne Orthoflavivirus that poses a significant public health risk in many temperate and tropical regions in Asia. Since the climate in some endemic countries is similar to temperate climates observed in Europe, understanding the role of specific mosquito species in the transmission of JEV is essential for predicting and effectively controlling the potential for the introduction and establishment of JEV in Europe.

METHODS

This study aimed to investigate the vector competence of colonized Culex pipiens biotype molestus mosquitoes for JEV. The mosquitoes were initially collected from the field in southern Sweden. The mosquitoes were offered a blood meal containing the Nakayama strain of JEV (genotype III), and infection rates, dissemination rates, and transmission rates were evaluated at 14, 21, and 28 days post-feeding.

RESULTS

The study revealed that colonized Swedish Cx. pipiens are susceptible to JEV infection, with a stable infection rate of around 10% at all timepoints. However, the virus was only detected in the legs of one mosquito at 21 days post-feeding, and no mosquito saliva contained JEV.

CONCLUSIONS

Overall, this research shows that Swedish Cx. pipiens can become infected with JEV, and emphasizes the importance of further understanding of the thresholds and barriers for JEV dissemination in mosquitoes.

Do it yourself: 3D-printed miniature CDC trap for adult mosquito (Diptera: Culicidae) surveillance

The central component of mosquito and vector surveillance programs globally is the adult mosquito trap, which is intended to collect host-seeking mosquitoes. The miniature CDC trap is a widely distributed trap style in part due to its relative affordability and compact nature. Despite already being a simple trap, in-house production methods, such as 3D printing, could improve the accessibility of the CDC trap by eliminating some of the supply chain variables. We present here several trials with the Salt Lake City (SLC) trap, a three-dimensional (3D) printed trap design. Functional assessments were made on secondary components and found no statistically significant differences when comparing CO2 line height (above vs. below fan), battery types (sealed lead acid vs. USB battery pack), and trap body collection shape (funnel body vs. simple/straight body). The SLC trap was compared directly to a commercial equivalent, the ABC trap, with comparative assessment on species diversity and evenness in collections and found to be statistically equivalent on all metrics. Methods also detail an accompanying optional transport system for a pressurized CO2/regulator set-up, should a practitioner elect not to use dry ice. Our final design is presented here with the publicly published stereolithography (STL) files and a detailed outline of the transport container system. Alternative models are available for in-house manufacture of mosquito traps, and we contribute these designs in an effort to stimulate further growth in vector surveillance.

Genetic differentiation among Aedes aegypti populations from different eco-geographical zones of India

The present study explicitly evaluated the genetic structure of Aedes aegypti Linn, the vector of dengue, chikungunya, and Zika viruses, across different geo-climatic zones of India and also elucidated the impact of ecological and topographic factors. After data quality checks and removal of samples with excess null alleles, the final analysis was performed on 589 individual samples using 10 microsatellite markers. Overall findings of this study suggested that, Ae. aegypti populations are highly diverse with moderate genetic differentiation between them. Around half of the populations (13 out of 22) formed two genetic clusters roughly associated with geographical regions. The remaining nine populations shared genetic ancestries with either one or both of the clusters. A significant relationship between genetic and geographic distance was observed, indicating isolation by distance. However, spatial autocorrelation analysis predicted the signs of long-distance admixture. Post-hoc environmental association analysis showed that 52.7% of genetic variations were explained by a combination of climatic and topographic factors, with latitude and temperature being the best predictors. This study indicated that though overall genetic differentiation among Ae. aegypti populations across India is moderate (Fst = 0.099), the differences between the populations are developing due to the factors associated with geographic locations. This study improves the understanding of the Ae. aegypti population structure in India that may assist in predicting mosquito movements across the geo-climatic zones, enabling effective control strategies and assessing the risk of disease transmission.

RNA interference to combat the Asian tiger mosquito in Europe: A pathway from design of an innovative vector control tool to its application

The Asian tiger mosquito Aedes albopictus is currently spreading across Europe, facilitated by climate change and global transportation. It is a vector of arboviruses causing human diseases such as chikungunya, dengue hemorrhagic fever and Zika fever. For the majority of these diseases, no vaccines or therapeutics are available. Options for the control of Ae. albopictus are limited by European regulations introduced to protect biodiversity by restricting or phasing out the use of pesticides, genetically modified organisms (GMOs) or products of genome editing. Alternative solutions are thus urgently needed to avoid a future scenario in which Europe faces a choice between prioritizing human health or biodiversity when it comes to Aedes-vectored pathogens. To ensure regulatory compliance and public acceptance, these solutions should preferably not be based on chemicals or GMOs and must be cost-efficient and specific. The present review aims to synthesize available evidence on RNAi-based mosquito vector control and its potential for application in the European Union. The recent literature has identified some potential target sites in Ae. albopictus and formulations for delivery. However, we found little information concerning non-target effects on the environment or human health, on social aspects, regulatory frameworks, or on management perspectives. We propose optimal designs for RNAi-based vector control tools against Ae. albopictus (target product profiles), discuss their efficacy and reflect on potential risks to environmental health and the importance of societal aspects. The roadmap from design to application will provide readers with a comprehensive perspective on the application of emerging RNAi-based vector control tools for the suppression of Ae. albopictus populations with special focus on Europe.

Genetic Diversity of Dengue Vector Aedes albopictus Collected from South Korea, Japan, and Laos

Aedes albopictus is native to Southeast Asia and has emerged as a major vector for vector-borne diseases that are spreading rapidly worldwide. Recent studies have shown that Ae. albopictus populations have different genetic groups dependent on their thermal adaptations; however, studies on Korean populations are limited. In this study, we analyzed the genetic diversity and structure of two mitochondrial genes (COI and ND5) and sixteen microsatellites in mosquitoes inhabiting Korea, Japan, and Laos. The results indicate that the Korean population has low genetic diversity, with an independent cluster distinct from the Laos population. Mixed clusters have also been observed in the Korean population. On the basis of these findings, two hypotheses are proposed. First, certain Korean populations are native. Second, some subpopulations that descended from the metapopulation (East Asian countries) were introduced to Japan before migrating to Korea. Furthermore, we previously demonstrated that Ae. albopictus appears to have been imported to Korea. In conclusion, the dengue-virus-carrying mosquitoes could migrate to Korea from Southeast Asian epidemic regions, where they can survive during the severe winter months. The key findings can be used to establish an integrated pest management strategy based on population genetics for the Korean Ae. albopictus population.

Biting the hand that feeds: Anthropogenic drivers interactively make mosquitoes thrive

Anthropogenic stressors on the environment are increasing at unprecedented rates and include urbanization, nutrient pollution, water management, altered land use and climate change. Their effects on disease vectors are poorly understood. A series of full factorial experiments investigated how key human induced abiotic pressures, and interactions between these, affect population parameters of the cosmopolitan disease vector, Culex pipiens s.l. Selected pressures include eutrophication, salinity, mean temperature, and temperature fluctuation. Data were collected for each individual pressure and for potential interactions between eutrophication, salinization and temperature. All experiments assessed survival, time to pupation, time to emergence, sex-ratio and ovipositioning behavior. The results show that stressors affect vector survival, may speed up development and alter female to male ratio, although large differences between stressors exist to quite different extents. While positive effects of increasing levels of eutrophication on survival were consistent, negative effects of salinity on survival were only apparent at higher temperatures, thus indicating a strong interaction effect between salinization and temperature. Temperature had no independent effect on larval survival. Overall, increasing eutrophication and temperatures, and the fluctuations thereof, lowered development rate, time to pupation and time to emergence while increasing levels of salinity increased development time. Higher levels of eutrophication positively impacted egg-laying behavior; the reverse was found for salinity while no effects of temperature on egg-laying behavior were observed. Results suggest large and positive impacts of anthropogenically induced habitat alterations on mosquito population dynamics. Many of these effects are exacerbated by increasing temperatures and fluctuations therein. In a world where eutrophication and salinization are increasingly abundant, mosquitoes are likely important benefactors. Ultimately, this study illustrates the importance of including multiple and combined stressors in predictive models as well as in prevention and mitigation strategies, particularly because they resonate with possible, but yet underdeveloped action plans.

Mosquitoes Know No Borders: Surveillance of Potential Introduction of Aedes Species in Southern Québec, Canada

Current climatic conditions limit the distribution of Aedes (Stegomyia) albopictus (Skuse, Diptera: Culicidae) in the north, but predictive climate models suggest this species could establish itself in southern Canada by 2040. A vector of chikungunya, dengue, yellow fever, Zika and West Nile viruses, the Ae. Albopictus has been detected in Windsor, Ontario since 2016. Given the potential public health implications, and knowing that Aedes spp. can easily be introduced by ground transportation, this study aimed to determine if specimens could be detected, using an adequate methodology, in southern Québec. Mosquitoes were sampled in 2016 and 2017 along the main roads connecting Canada and the U.S., using Biogent traps (Sentinel-2, Gravide Aedes traps) and ovitraps. Overall, 24 mosquito spp. were captured, excluding Ae. Albopictus, but detecting one Aedes (Stegomyia) aegypti (Skuse) specimen (laid eggs). The most frequent species among captured adults were Ochlerotatus triseriatus, Culex pipiens complex, and Ochlerotatus japonicus (31.0%, 26.0%, and 17.3%, respectively). The present study adds to the increasing number of studies reporting on the range expansions of these mosquito species, and suggests that ongoing monitoring, using multiple capture techniques targeting a wide range of species, may provide useful information to public health with respect to the growing risk of emerging mosquito-borne diseases in southern Canada.

Two New Alternatives to the Conventional Arm-in-Cage Test for Assessing Topical Repellents

European guidelines for testing attractant and repellent efficacy (i.e., Product type 19 [PT19]) have been in revision since 2017. A key topic of discussion is the current approach to evaluating topical repellents. The European Chemical Agency has stated field testing should be avoided because of mosquito-borne disease risks. However, the most common laboratory method, the arm-in-cage (AIC) test, may limit the reliable extrapolation of lab results to field conditions. This study's main goal was to assess alternative laboratory methods for evaluating topical mosquito repellents that use mosquito landing rates more representative of those in the field. The study took place at three European testing labs using 30 study participants per test and the mosquito, Aedes albopictus (Skuse, 1894, Diptera: Culicidae). In phase 1, a conventional AIC test and a sleeved AIC test were performed. Respectively, the arm area exposed was 600 and 100 cm2, and cage volume was 0.040 and 0.064 m3. Mosquito density was the same for both: 1 female/840 cm3. In phase 2, room-based testing (40 ± 5 mosquitoes in 25-30 m3) was used as a proxy for field testing. The mosquito repellent employed was 15% N,N-diethyl-m-toluamide in ethanol at two doses: 1 and 0.5 g/600 cm2. The protection times measured at each laboratory were analyzed both separately and together using nonparametric (Kruskal-Wallis) test. The two alternatives methods showed to be potential alternatives to the current AIC method recreated field mosquito landing rates and achieved reproducible protection times across laboratories.

Diversity of mosquito fauna (Diptera, Culicidae) in higher-altitude regions of Croatia

Global climate change and the accompanying rise in temperature could affect the biology and ecology of a number of vectors, including mosquitoes. High altitude areas that were previously unsuitable for the spread of mosquito vector populations could become suitable. The aim of this research was to study the distribution of mosquito species in higher altitude regions of Croatia. Samples were collected in three areas: Slavonian Mountains, Gorski Kotar, and Middle Velebit. Specimens were morphologically determined and confirmed by DNA barcoding and other genetic markers and showed the presence of 16 species belonging to six genera. The most abundant species were the Culex pipiens complex with 50% of the collected specimens. Both pipiens (Linnaeus, 1758) and molestus (Forskal, 1775) biotypes and their hybrids were identified within the complex, followed by Culex torrentium (Martini, 1925) (20.2%), Culiseta longiareolata (Macquart, 1838) (8.5%), and the invasive species Aedes japonicus (Theobald, 1901) (7.8% of the total number of collected specimens). The remaining 12 species made up 14.7% of the collected specimens. Intraspecific COI p-distances were within the standard barcoding threshold for OTUs, while interspecific genetic distances were much higher, confirming the existence of barcoding gaps. Mosquito fauna of Croatian mountains showed a moderate variety and made 30.8% of the total number of recorded mosquito species in Croatia thus far.

Semi-field evaluation of the exposure-free mosquito electrocuting trap and BG-Sentinel trap as an alternative to the human landing catch for measuring the efficacy of transfluthrin emanators against Aedes aegypti

BACKGROUND

The human landing catch (HLC) measures human exposure to mosquito bites and evaluates the efficacy of vector control tools. However, it may expose volunteers to potentially infected mosquitoes. The mosquito electrocuting trap (MET) and BG-Sentinel traps (BGS) represent alternative, exposure-free methods for sampling host-seeking mosquitoes. This study investigates whether these methods can be effectively used as alternatives to HLC for measuring the efficacy of transfluthrin emanator against Aedes aegypti.

METHODS

The protective efficacy (PE) of freestanding passive transfluthrin emanators (FTPEs), measured by HLC, MET and BGS, was compared in no-choice and choice tests. The collection methods were conducted 2 m from an experimental hut with FTPEs positioned at 3 m on either side of them. For the choice experiment, a competitor HLC was included 10 m from the first collection point. One hundred laboratory-reared Ae. aegypti mosquitoes were released and collected for 3 consecutive h.

RESULTS

In the no-choice test, each method measured similar PE: HLC: 66% (95% confidence interval [CI]: 50-82), MET: 55% (95% CI: 48-63) and BGS: 64% (95% CI: 54-73). The proportion of mosquitoes recaptured was consistent between methods (20-24%) in treatment and varied (47-71%) in the control. However, in choice tests, the PE measured by each method varied: HLC: 37% (95% CI: 25-50%), MET: 76% (95% CI: 61-92) and BGS trap: 0% (95% CI: 0-100). Recaptured mosquitoes were no longer consistent between methods in treatment (2-26%) and remained variable in the control (7-42%). FTPE provided 50% PE to the second HLC 10 m away. In the control, the MET and the BGS were less efficacious in collecting mosquitoes in the presence of a second HLC.

CONCLUSIONS

Measuring the PE in isolation was fairly consistent for HLC, MET and BGS. Because HLC is not advisable, it is reasonable to use either MET or BGS as a proxy for HLC for testing volatile pyrethroid (VP) in areas of active arbovirus-endemic areas. The presence of a human host in close proximity invalidated the PE estimates from BGS and METs. Findings also indicated that transfluthrin can protect multiple people in the peridomestic area and that at short range mosquitoes select humans over the BGS.

From the Field to the Laboratory: Quantifying Outdoor Mosquito Landing Rate to Better Evaluate Topical Repellents

Vector-borne diseases are a worldwide threat to human health. Often, no vaccines or treatments exist. Thus, personal protection products play an essential role in limiting transmission. The World Health Organization (WHO) arm-in-cage (AIC) test is the most common method for evaluating the efficacy of topical repellents, but it remains unclear whether AIC testing conditions recreate the mosquito landing rates in the field. This study aimed to estimate the landing rate outdoors, in an area of Europe highly infested with the Asian tiger mosquito (Aedes albopictus (Skuse, 1894, Diptera: Culididae)), and to determine how to replicate this rate in the laboratory. To assess the landing rate in the field, 16 individuals were exposed to mosquitoes in a highly infested region of Italy. These field results were then compared to results obtained in the laboratory: 1) in a 30 m3 room where nine volunteers were exposed to different mosquito abundances (ranges: 15-20, 25-30, and 45-50) and 2) in a 0.064 m3 AIC test cage where 10 individuals exposed their arms to 200 mosquitoes (as per WHO requirements). The highest mosquito landing rate in the field was 26.8 landings/min. In the room test, a similar landing rate was achieved using 15-20 mosquitoes (density: 0.50-0.66 mosquitoes/m3) and an exposure time of 3 min. In the AIC test using 200 mosquitoes (density: 3,125 mosquitoes/m3), the landing rate was 229 ± 48 landings/min. This study provides useful reference values that can be employed to design new evaluation standards for topical repellents that better simulate field conditions.

The Larval Density of Mosquitos (Diptera: Culicidae) in Jiaxiang County, Shandong Province, China: Influence of Bacterial Diversity, Richness, and Physicochemical Factors

As Jiaxiang County of Shandong province is an area with complex mosquito vector composition, it is necessary to investigate the relationship between bacterial diversity, physicochemical factors, and larval density. Therefore, the physicochemical properties of 46 breeding sites for six kinds of habitat types (small puddles, small water containers, paddy fields, large water containers, irrigation channels, and drainage ditches) were investigated by a multiparameter analyzer; the water’s bacterial diversity was analyzed by the 16S rRNA full-length sequencing method. Spearman correlation and multiple linear regression were used to analyze the correlation between larval density and variables. The variables analyzed were dissolved oxygen, pH, hardness, turbidity, conductivity, temperature, ammonia nitrogen, water depth, and distance from the nearest house. One-Way ANOVA was used to understand whether there are differences in bacterial diversity in different habitats. Pearson linear correlation model was used to analyze the effects of bacterial diversity and richness on mosquito densities in breeding sites. A total of 3291 larvae were captured, and a total of 6 species of 4 genera were identified. The identified species were Culex pipiens pallens, Aedes albopictus, Anopheles sinensis, Culex tritaeniorhynchus, Culex bitaeniorhynchus, and Mansonia uniformis. The density and species can be jointly affected by physicochemical properties and bacterial diversity, especially Shannon index and distance from the nearest house. In general, the physicochemical parameters and bacterial diversity of different habitats were significantly different. Even for the same habitat type, the physicochemical parameters varied greatly due to different environments.

Biting rhythm and demographic attributes of Aedes albopictus (Skuse) females from different urbanized settings in Penang Island, Malaysia under uncontrolled laboratory conditions

Urbanization could potentially modify Aedes albopictus' ecology by changing the dynamics of the species, and affecting their breeding sites due to environmental changes, and thus contribute to dengue outbreaks. Thus, this study was conducted to evaluate the biting rhythm, fecundity and longevity of adult female Ae. albopictus in relation to urbanization strata; urban, suburban and rural areas in Penang Island, Malaysia. The experiments were done in comparison to a laboratory strain. Twenty-four hours biting activity of all the mosquito strains showed a clear bimodal biting activity, with morning and evening twilight peaks. The interaction effect between biting time and mosquito strains was not significant. Meanwhile, differences in fecundity among mosquito strains were statistically significant (F(3,442) = 10.559, P < 0.05) with urban areas having higher mean number of eggs (mean = 107.69, standard error = 3.98) than suburban (mean = 94.48, standard error = 5.18), and rural areas (mean = 72.52, standard error = 3.87). Longevity of adult females were significantly higher (F(3,441) = 31.259, P < 0.05) for mosquito strains from urban areas compared to the other strains. These findings would provide crucial information for the planning of control programs in Malaysia, particularly Penang.

Investigation of mosquito larval habitats and insecticide resistance in an area with a high incidence of mosquito-borne diseases in Jining, Shandong Province

BACKGROUND

To investigate mosquito larval habitats and resistance to common insecticides in areas with high incidence rates of mosquito-borne diseases in Jining, Shandong Province, and to provide a scientific basis for the future prevention and control of mosquito-borne diseases and the rational use of insecticides.

METHODS AND RESULTS

From June to September 2018, mosquito habitat characteristics and species compositions in Jintun town were studied through a cross-sectional survey. Larvae and pupae were collected in different habitats using the standard dipping technique. A total of 7,815 mosquitoes, comprising 7 species from 4 genera, were collected. Among them, Culex pipiens pallens (n = 5,336, 68.28%) was the local dominant species and found in all four habitats (rice paddies, irrigation channels, water containers, drainage ditches). There were 1,708 Cx. tritaeniorhynchus (21.85%), 399 Anopheles sinensis (5.11%), 213 Armigeres subalbatus (2.72%), 124 Aedes albopictus (1.59%), and 35 other (Cx. bitaeniorhynchus and Cx. halifaxii) (0.45%) mosquito samples collected. Spearman correlation analysis was employed to evaluate the relationship between larval density and the physicochemical characteristics of the breeding habitat. It was found that the larval density of Cx. tritaeniorhynchus correlated positively with water depth (r = 0.927 p = 0.003), the larval density of An. sinensis correlated positively with dissolved oxygen (DO) (r = 0.775 p = 0.041) and the larval density of Cx. p. pallens correlated positively with ammonia nitrogen (r = 0.527 p = 0.002). Resistance bioassays were carried out on the dominant populations of Cx. p. pallens: mosquitoes presented very high resistance to cypermethrin and deltamethrin, moderate resistance to dichlorvos (DDVP), and low resistance to Bacillus thuringiensis israelensis (Bti), with decreased susceptibility to propoxur.

CONCLUSION

We showed that mosquito species vary across habitat type and that the mosquito larval density correlated positively with certain physicochemical characteristics in different habitats. In addition, Cx. p. pallens developed different levels of resistance to five insecticides. Vector monitoring should be strengthened after an epidemic, and further research should be conducted to scientifically prevent and kill mosquitoes.

First Report on Clinical Feline Heartworm (Dirofilaria Immitis) Infection in Romania

Dirofilaria immitis (Nematoda: Filarioidea) is the causative agent of heartworm disease (HWD), a severe and potentially fatal condition in dogs. Although cats are considered more resistant to infection than dogs, they are also susceptible to heartworm infection. Moreover, the clinical importance of feline dirofilariosis has increased in recent years, especially in heartworm endemic areas. In contrast to dog, definitive antemortem diagnosis of heartworm infection in cat is difficult to achieve and a combination of testing methods must be used for clinical confirmation. Here we describe a clinical case of heartworm infection in a 12-year-old male mixed breed cat, originated from Southern Romania, which was referred to a veterinary clinic with a history of vomiting and clinical signs of respiratory distress. The thoracic radiograph showed a diffuse bronchointerstitial pattern of the pulmonary parenchyma. The serological test for D. immitis circulating antibody was positive and heartworms were visualized by echocardiography in the main pulmonary artery. In conclusion, the present study clearly shows that cats are at risk for D. immitis infection in heartworm-endemic areas in Romania. Additionally, the findings highlight the urgent need for increased awareness among veterinary practitioners of the existence of feline heartworm diseases and for adequate prophylactic measures to be applied. To our knowledge, this is the first report on clinical evolution and radiographic and echocardiographic features of a naturally heartworm-infected cat in Romania.

A field-based modeling study on ecological characterization of hourly host-seeking behavior and its associated climatic variables in Aedes albopictus

BACKGROUND

The global spread of mosquito-borne diseases (MBD) has presented increasing challenges to public health. The transmission of MBD is mainly attributable to the biting behaviors of female mosquitoes. However, the ecological pattern of hourly host-seeking behavior in Aedes albopictus and its association with climatic variables are still not well understood, especially for a precise requirement for establishing an effective risk prediction system of MBD transmission.

METHODS

Mosquito samples and data on mosquito hourly density and site-specific climatic variables, including temperature, relative humidity, illuminance and wind speed, were collected simultaneously in urban outdoor environments in Guangzhou during 2016-2018. Kernel regression models were used to assess the temporal patterns of hourly host-seeking behavior in mosquito populations, and negative binomial regression models in the Bayesian framework were used to investigate the associations of host-seeking behavior with climatic variables.

RESULTS

Aedes albopictus was abundant, constituting 82% (5569/6790) of the total collected mosquitoes. Host-seeking behavior in Ae. albopictus varied across time and was significantly influenced by climatic variables. The predicted hourly mosquito densities showed non-linear relationships with temperature and illuminance, whereas density increased with relative humidity but generally decreased with wind speed. The range of temperature estimates for female biting was 16.4-37.1 °C, peaking at 26.5 °C (95% credible interval: 25.3-28.1). During the favorable periods, biting behavior of female Ae. albopictus was estimated to occur frequently all day long, presenting a bimodal distribution with peaks within 2-3 h around both dawn and dusk (05:00-08:00 h and 16:00-19:00 h). Moreover, a short-term association in hourly density between the females and males was found.

CONCLUSIONS

Our field-based modeling study reveals that hourly host-seeking behavior of Ae. albopictus exhibits a complex pattern, with hourly variation constrained significantly by climatic variables. These findings lay a foundation for improving MBD risk assessments as well as practical strategies for vector control. For instances of all-day-long frequent female biting during the favorable periods in Guangzhou, effective integrated mosquito control measures must be taken throughout the day and night.

A field-based modeling study on ecological characterization of hourly host-seeking behavior and its associated climatic variables in Aedes albopictus

BACKGROUND

The global spread of mosquito-borne diseases (MBD) has presented increasing challenges to public health. The transmission of MBD is mainly attributable to the biting behaviors of female mosquitoes. However, the ecological pattern of hourly host-seeking behavior in Aedes albopictus and its association with climatic variables are still not well understood, especially for a precise requirement for establishing an effective risk prediction system of MBD transmission.

METHODS

Mosquito samples and data on mosquito hourly density and site-specific climatic variables, including temperature, relative humidity, illuminance and wind speed, were collected simultaneously in urban outdoor environments in Guangzhou during 2016-2018. Kernel regression models were used to assess the temporal patterns of hourly host-seeking behavior in mosquito populations, and negative binomial regression models in the Bayesian framework were used to investigate the associations of host-seeking behavior with climatic variables.

RESULTS

Aedes albopictus was abundant, constituting 82% (5569/6790) of the total collected mosquitoes. Host-seeking behavior in Ae. albopictus varied across time and was significantly influenced by climatic variables. The predicted hourly mosquito densities showed non-linear relationships with temperature and illuminance, whereas density increased with relative humidity but generally decreased with wind speed. The range of temperature estimates for female biting was 16.4-37.1 °C, peaking at 26.5 °C (95% credible interval: 25.3-28.1). During the favorable periods, biting behavior of female Ae. albopictus was estimated to occur frequently all day long, presenting a bimodal distribution with peaks within 2-3 h around both dawn and dusk (05:00-08:00 h and 16:00-19:00 h). Moreover, a short-term association in hourly density between the females and males was found.

CONCLUSIONS

Our field-based modeling study reveals that hourly host-seeking behavior of Ae. albopictus exhibits a complex pattern, with hourly variation constrained significantly by climatic variables. These findings lay a foundation for improving MBD risk assessments as well as practical strategies for vector control. For instances of all-day-long frequent female biting during the favorable periods in Guangzhou, effective integrated mosquito control measures must be taken throughout the day and night.

Climatic Conditions: Conventional and Nanotechnology-Based Methods for the Control of Mosquito Vectors Causing Human Health Issues

Climate variability is highly impacting on mosquito-borne diseases causing malaria and dengue fever across the globe. Seasonal variability change in temperature and rainfall patterns are impacting on human health. Mosquitoes cause diseases like dengue fever, yellow fever, malaria, Chikungunya, West Nile and Japanese encephalitis. According to estimations by health organizations, annually one million human deaths are caused by vector-borne diseases, and dengue fever has increased about 30-fold over the past 50 years. Similarly, over 200 million cases of malaria are being reported annually. Mosquito-borne diseases are sensitive to temperature, humidity and seasonal variability. Both conventional (environmental, chemical, mechanical, biological etc.) and nanotechnology-based (Liposomes, nano-suspensions and polymer-based nanoparticles) approaches are used for the eradication of Malaria and dengue fever. Now green approaches are used to eradicate mosquitoes to save human health without harming the environment. In this review, the impact of climatic conditions on mosquito-borne diseases along with conventional and nanotechnology-based approaches used for controlling malaria and dengue fever have been discussed. Important recommendations have been made for people to stay healthy.

Towards harmonisation of entomological surveillance in the Mediterranean area

BACKGROUND

The Mediterranean Basin is historically a hotspot for trade, transport, and migration. As a result, countries surrounding the Mediterranean Sea share common public health threats. Among them are vector-borne diseases, and in particular, mosquito-borne viral diseases are prime candidates as (re)emerging diseases and are likely to spread across the area. Improving preparedness and response capacities to these threats at the regional level is therefore a major issue. The implementation of entomological surveillance is, in particular, of utmost importance. Guidance in designing entomological surveillance systems is critical, and these systems may pursue different specific objectives depending on the disease. The purpose of the proposed review is to draw up guidelines for designing effective and sustainable entomological surveillance systems in order to improve preparedness and response. However, we make it clear that there is no universal surveillance system, so the thinking behind harmonisation is to define evidence-based standards in order to promote best practises, identify the most appropriate surveillance activities, and optimise the use of resources. Such guidance is aimed at policymakers and diverse stakeholders and is intended to be used as a framework for the implementation of entomological surveillance programmes. It will also be useful to collaborate and share information with health professionals involved in other areas of disease surveillance. Medical entomologists and vector control professionals will be able to refer to this report to advocate for tailored entomological surveillance strategies. The main threats targeted in this review are the vectors of dengue virus, chikungunya virus, Zika virus, West Nile virus, and Rift Valley fever virus. The vectors of all these arboviruses are mosquitoes.

METHODS

Current knowledge on vector surveillance in the Mediterranean area is reviewed. The analysis was carried out by a collaboration of the medical entomology experts in the region, all of whom belong to the MediLabSecure network, which is currently funded by the European Union and represents an international effort encompassing 19 countries in the Mediterranean and Black Sea region.

FINDINGS

Robust surveillance systems are required to address the globalisation of emerging arboviruses. The prevention and management of mosquito-borne viral diseases must be addressed in the prism of a One Health strategy that includes entomological surveillance as an integral part of the policy. Entomological surveillance systems should be designed according to the entomological and epidemiological context and must have well-defined objectives in order to effect a tailored and graduated response. We therefore rely on different scenarios according to different entomological and epidemiological contexts and set out detailed objectives of surveillance. The development of multidisciplinary networks involving both academics and public authorities will provide resources to address these health challenges by promoting good practises in surveillance (identification of surveillance aims, design of surveillance systems, data collection, dissemination of surveillance results, evaluation of surveillance activities) and through the sharing of effective knowledge and information. These networks will also contribute to capacity building and stronger collaborations between sectors at both the local and regional levels. Finally, concrete guidance is offered on the vector of the main arbovirus based on the current situation in the area.

The composition, diversity, and distribution of mosquito fauna (Diptera: Culicidae) in Kosovo

The aim of this study is to identify the mosquito species that currently exist and their distributions in Kosovo in order to determine current potential endemic zones and areas at a higher risk for future epidemics. These scientific data will be shared with public health authorities for implementing mosquito control programs. During a two-year period of monitoring in 48 localities in 23 provinces in Kosovo, a total of 1,604 mosquitoes representing 13 species and six genera were collected and morphologically identified. Members of species complexes were also classified to species using DNA barcoding. In total, 13 species were identified with Culex pipiens s.l., the predominant species with an abundance rate of 39%. The remaining 12 species identified were grouped into five genera: Anopheles, Aedes, Coquillettidia, Culiseta, Uranotaenia, including species that are vectors of arboviruses in other parts of the world.

A method for assessing mitochondrial physiology using mechanically permeabilized flight muscle of Aedes aegypti mosquitoes

Aedes aegypti is the most important and widespread vector of arboviruses, including dengue and zika. Insect dispersal through the flight activity is a key parameter that determines vector competence, and is energetically driven by oxidative phosphorylation in flight muscle mitochondria. Analysis of mitochondrial function is central for a better understanding of cellular metabolism, and is mostly studied using isolated organelles. However, this approach has several challenges and methods for assessment of mitochondrial function in chemically-permeabilized tissues were designed. Here, we described a reliable protocol to assess mitochondrial physiology using mechanically permeabilized flight muscle of single A. aegypti mosquitoes in combination with high-resolution respirometry. By avoiding the use of detergents, high respiratory rates were obtained indicating that substrate access to mitochondria was not limited. This was confirmed by using selective inhibitors for specific mitochondrial substrates. Additionally, mitochondria revealed highly coupled, as ATP synthase or adenine nucleotide translocator inhibition strongly impacted respiration. Finally, we determined that pyruvate and proline induced the highest respiratory rates compared to other substrates tested. This method allows the assessment of mitochondrial physiology in mosquito flight muscle at individual level, and can be used for the identification of novel targets aiming rational insect vector control.

The impact of industrial activities on vector-borne disease transmission

Industrial activities have produced profound changes in the natural environment, including the mass removal of trees, fragmentation of habitats, and creation of larval mosquito breeding sites, that have allowed the vectors of disease pathogens to thrive. We conducted a review of the literature to assess the impact of industrial activities on vector-borne disease transmission. Our study shows that industrial activities may be coupled with significant changes to human demographics that can potentially increase contact between pathogens, vectors and hosts, and produce a shift of parasites and susceptible populations between low and high disease endemic areas. Indeed, where vector-borne diseases and industrial activities intersect, large numbers of potentially immunologically naïve people may be exposed to infection and lack the knowledge and means to protect themselves from infection. Such areas are typically associated with inadequate access to quality health care, thus allowing industrial development and production sites to become important foci of transmission. The altered local vector ecologies, and the changes in disease dynamics that changes affect, create challenges for under-resourced health care and vector-control systems.

Expected Changes of Montenegrin Climate, Impact on the Establishment and Spread of the Asian Tiger Mosquito (Aedes albopictus), and Validation of the Model and Model-Based Field Sampling

Aedes albopictus has become established in many parts of Europe since its introduction at the end of the 20th century. It can vector a range of arboviruses, of which Chikungunya and Dengue are most significant for Europe. An analysis of the expected climate change and the related shift in Köppen zones for Montenegro and impact on the establishment of Ae. albopictus was conducted. Outputs of a mechanistic Aedes albopictus model were validated by 2245 presence/absence records collected from 237 different sites between 2001 and 2014. Finally, model-based sampling was designed and performed at 48 sites in 2015, in a previously unexplored northern part of Montenegro, and results were validated. The Eta Belgrade University (EBU)-Princeton Ocean Model (POM) regional climate model was used with the A2 emissions scenario for the 2001–2030 and 2071–2100 integration periods. The results point to a significant increase in suitability for the mosquito and a vertical shift to higher altitudes by the end of the century. The model showed excellent results with the area under the receiver operating characteristic curve (AUC) of 0.94. This study provides a tool for prioritizing surveillance efforts (model-based surveillance), especially when resources are limited. This is the first published analysis of Climate Change that incorporates observations from the national synoptic grid and the subsequent impact on Ae. albopictus in Montenegro.

The Effectiveness of Asian Bush Mosquito (Aedes japonicus japonicus) Control Actions in Colonised Peri-urban Areas in the Netherlands

The Asian bush mosquito (Aedes japonicus japonicus (Theobald)) is an invasive mosquito species in Europe. In 2012, it was for the first time detected in the Netherlands, in the municipality of Lelystad. After further research, thousands of specimens were found in the surrounding peri-urban areas of the city. A targeted mosquito control campaign began in 2015 with the objective of reducing populations in locations with the highest concentrations of Ae. japonicus breeding sites: allotment garden complexes. Mosquito control consisted of source reduction combined with application of the larvicide Vectomax in breeding sites. At eight complexes, mosquito control effectiveness has been systematically measured by sampling larvae from breeding sites. Six measurements were performed between 2015 and 2016. Results show that the effectiveness of mosquito control actions was similar in all treated allotment gardens and resulted in a significant reduction in Ae. japonicus larval abundance. Rain barrels at the allotments represent the most frequent breeding site in Lelystad, but every water filled artificial container is a potential breeding site for the species. Ae. japonicus was not found in the samples taken in other allotment gardens in the province of Flevoland; however, the collection methodology used proven to be effective in detecting this species when it has newly colonized surrounding areas. Targeted mosquito control actions at the breeding sites are crucial for successful reduction of populations of an invasive mosquito species, and systematic measurements of the effectiveness, is in this case, the base to understand the dynamics of Ae. japonicus populations after mosquito control.

Community analysis of the abundance and diversity of mosquito species (Diptera: Culicidae) in three European countries at different latitudes

BACKGROUND

Studies on mosquito species diversity in Europe often focus on a specific habitat, region or country. Moreover, different trap types are used for these sampling studies, making it difficult to compare and validate results across Europe. To facilitate comparisons of trapping sites and community analysis, the present study used two trap types for monitoring mosquito species diversity in three habitat types for three different countries in Europe.

METHODS

Mosquitoes were trapped using Biogents Sentinel (BGS), and Mosquito Magnet Liberty Plus (MMLP) traps at a total of 27 locations in Sweden, the Netherlands and Italy, comprising farm, peri-urban and wetland habitats. From July 2014 to June 2015 all locations were sampled monthly, except for the winter months. Indices of species richness, evenness and diversity were calculated, and community analyses were carried out with non-metric multidimensional scaling (NMDS) techniques.

RESULTS

A total of 11,745 female mosquitoes were trapped during 887 collections. More than 90% of the mosquitoes belonged to the genera Culex and Aedes, with Culex pipiens being the most abundant species. The highest mosquito diversity was found in Sweden. Within Sweden, species diversity was highest in wetland habitats, whereas in the Netherlands and Italy this was highest at farms. The NMDS analyses showed clear differences in mosquito communities among countries, but not among habitat types. The MMLP trapped a higher diversity of mosquito species than the BGS traps. Also, MMLP traps trapped higher numbers of mosquitoes, except for the genera Culex and Culiseta in Italy.

CONCLUSIONS

A core mosquito community could be identified for the three countries, with Culex pipiens as the most abundant species. Differences in mosquito species communities were more defined by the three countries included in the study than by the three habitat types. Differences in mosquito community composition across countries may have implications for disease emergence and further spread throughout Europe. Future research should, therefore, focus on how field data of vector communities can be incorporated into models, to better assess the risk of mosquito-borne disease outbreaks.

The use of sequential mark-release-recapture experiments to estimate population size, survival and dispersal of male mosquitoes of the Anopheles gambiae complex in Bana, a west African humid savannah village

Background

Vector control is a major component of the malaria control strategy. The increasing spread of insecticide resistance has encouraged the development of new tools such as genetic control which use releases of modified male mosquitoes. The use of male mosquitoes as part of a control strategy requires an improved understanding of male mosquito biology, including the factors influencing their survival and dispersal, as well as the ability to accurately estimate the size of a target mosquito population. This study was designed to determine the seasonal variation in population size via repeated mark-release-recapture experiments and to estimate the survival and dispersal of male mosquitoes of the Anopheles gambiae complex in a small west African village.

Methods

Mark-release-recapture experiments were carried out in Bana Village over two consecutive years, during the wet and the dry seasons. For each experiment, around 5000 (3407–5273) adult male Anopheles coluzzii mosquitoes were marked using three different colour dye powders (red, blue and green) and released in three different locations in the village (centre, edge and outside). Mosquitoes were recaptured at sites spread over the village for seven consecutive days following the releases. Three different capture methods were used: clay pots, pyrethroid spray catches and swarm sampling.

Results

Swarm sampling was the most productive method for recapturing male mosquitoes in the field. Population size and survival were estimated by Bayesian analyses of the Fisher-Ford model, revealing an about 10-fold increase in population size estimates between the end of dry season (10,000–50,000) to the wet season (100,000–500,000). There were no detectable seasonal effects on mosquito survival, suggesting that factors other than weather may play an important role. Mosquito dispersal ranged from 40 to 549 m over the seven days of each study and was not influenced by the season, but mainly by the release location, which explained more than 44% of the variance in net dispersal distance.

Conclusion

This study clearly shows that male-based MRR experiments can be used to estimate some parameters of wild male populations such as population size, survival, and dispersal and to estimate the spatial patterns of movement in a given locality.

Mosquitoes (Diptera: Culicidae) in Mauritania: a review of their biodiversity, distribution and medical importance

Although mosquitoes (Diptera: Culicidae) are important disease vectors, information on their biodiversity in Mauritania is scarce and very dispersed in the literature. Data from the scientific literature gathered in the country from 1948 to 2016 were collected and analyzed. Overall 51 culicid species comprising 17 Anopheles spp., 14 Aedes spp., 18 Culex spp. and two Mansonia spp. have been described in Mauritania among which Anopheles arabiensis, Aedes vexans, Culex poicilipes and Culex antennatus are of epidemiological significance. Anopheles arabiensis is widely distributed throughout the country and its geographic distribution has increased northwards in recent years, shifting its northern limit form 17°32′N in the 1960s to 18°47′N today. Its presence in the central region of Tagant highlights the great ecological plasticity of the species. Conversely, the distribution of Anopheles gambiae (s.s.) and Anopheles melas has shrunk compared to that of the 1960s. Anopheles rhodesiensis and An. d’thali are mainly confined in the mountainous areas (alt. 200–700 m), whereas Anopheles pharoensis is widely distributed in the Senegal River basin. Culex poicilipes and Cx. antenattus were naturally found infected with Rift valley fever virus in central and northern Mauritania following the Rift valley outbreaks of 1998 and 2012. Recently, Ae. aegypti emerged in Nouakchott and is probably responsible for dengue fever episodes of 2015. This paper provides a concise and up-to-date overview of the existing literature on mosquito species known to occur in Mauritania and highlights areas where future studies should fill a gap in knowledge about vector biodiversity. It aims to help ongoing and future research on mosquitoes particularly in the field of medical entomology to inform evidence-based decision-making for vector control and management strategies.

Direct PCR of indigenous and invasive mosquito species: a time- and cost-effective technique of mosquito barcoding

Millions of people die each year as a result of pathogens transmitted by mosquitoes. However, the morphological identification of mosquito species can be difficult even for experts. The identification of morphologically indistinguishable species, such as members of the Anopheles maculipennis complex (Diptera: Culicidae), and possible hybrids, such as Culex pipiens pipiens/Culex pipiens molestus (Diptera: Culicidae), presents a major problem. In addition, the detection and discrimination of newly introduced species can be challenging, particularly to researchers without previous experience. Because of their medical importance, the clear identification of all relevant mosquito species is essential. Using the direct polymerase chain reaction (PCR) method described here, DNA amplification without prior DNA extraction is possible and thus species identification after sequencing can be achieved. Different amounts of tissue (leg, head; larvae or adult) as well as different storage conditions (dry, ethanol, -20 and -80 °C) and storage times were successfully applied and showed positive results after amplification and gel electrophoresis. Overall, 28 different indigenous and non-indigenous mosquito species were analysed using a gene fragment of the COX1 gene for species differentiation and identification by sequencing this 658-bp fragment. Compared with standard PCR, this method is time- and cost-effective and could thus improve existing surveillance and control programmes.

Current distribution of the invasive mosquito species, Aedes koreicus [Hulecoeteomyia koreica] in northern Italy

Background

The invasive species Aedes (Finlaya) koreicus was first identified in north-eastern Italy in 2011, during the ongoing surveillance activity of Aedes albopictus. Following this finding, a more intensive monitoring was carried out to assess the distribution of the species and to collect biological data. Herein, we report the new records obtained by four years of surveillance.

Findings

The presence of Ae. koreicus was checked using ovitraps, adults traps and by larval collections in all possible breeding sites from May 2011 to July 2015. The monitoring started in the site of the first detection (Province of Belluno) and was then extended in the neighbouring Provinces belonging to four Regions. Aedes koreicus was found in 73 municipalities out of 155 monitored (47.1 %), including 23 municipalities (14.8 %) previously not infested. The area of first detection of Ae. koreicus (Province of Belluno) was also the most infested (68 %). However the mosquito has also been found to the west (Province of Trento) and to the south and south-west (Provinces of Vicenza and Treviso) of the initially infested area.

Conclusions

The spread of Ae. koreicus is directed towards south and west from the original infested area, likely due to the dense road connections and the habitat suitability of the new areas. According to these records, northern Italy has a high probability to be invaded by Ae. koreicus in the next decade. These data can be useful to validate predictive models of potential distribution and dispersal of this species in Italy or in Europe.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-1208-4) contains supplementary material, which is available to authorized users.

Control methods against invasive Aedes mosquitoes in Europe: a review

Five species of invasive Aedes mosquitoes have recently become established in Europe: Ae. albopictus, Ae. aegypti, Ae. japonicus japonicus, Ae. koreicus and Ae. atropalpus. These mosquitoes are a serious nuisance for people and are also competent vectors for several exotic pathogens such as dengue and chikungunya viruses. As they are a growing public health concern, methods to control these mosquitoes need to be implemented to reduce their biting and their potential for disease transmission. There is a crucial need to evaluate methods as part of an integrated invasive mosquito species control strategy in different European countries, taking into account local Aedes infestations and European regulations. This review presents the control methods available or in development against invasive Aedes mosquitoes, with a particular focus on those that can be implemented in Europe. These control methods are divided into five categories: environmental (source reduction), mechanical (trapping), biological (e.g. copepods, Bacillus thuringiensis var. israelensis, Wolbachia), chemical (insect growth regulators, pyrethroids) and genetic (sterile insect technique and genetically modified mosquitoes). We discuss the effectiveness, ecological impact, sustainability and stage of development of each control method.

Recent and projected future climatic suitability of North America for the Asian tiger mosquito Aedes albopictus

Background

Since the 1980s, populations of the Asian tiger mosquito Aedes albopictus have become established in south-eastern, eastern and central United States, extending to approximately 40°N. Ae. albopictus is a vector of a wide range of human pathogens including dengue and chikungunya viruses, which are currently emerging in the Caribbean and Central America and posing a threat to North America.

Methods

The risk of Ae. albopictus expanding its geographic range in North America under current and future climate was assessed using three climatic indicators of Ae. albopictus survival: overwintering conditions (OW), OW combined with annual air temperature (OWAT), and a linear index of precipitation and air temperature suitability expressed through a sigmoidal function (SIG). The capacity of these indicators to predict Ae. albopictus occurrence was evaluated using surveillance data from the United States. Projected future climatic suitability for Ae. albopictus was obtained using output of nine Regional Climate Model experiments (RCMs).

Results

OW and OWAT showed >90% specificity and sensitivity in predicting observed Ae. albopictus occurrence and also predicted moderate to high risk of Ae. albopictus invasion in Pacific coastal areas of the Unites States and Canada under current climate. SIG also well predicted observed Ae. albopictus occurrence (ROC area under the curve was 0.92) but predicted wider current climatic suitability in the north-central and north-eastern United States and south-eastern Canada. RCM output projected modest (circa 500 km) future northward range expansion of Ae. albopictus by the 2050s when using OW and OWAT indicators, but greater (600–1000 km) range expansion, particularly in eastern and central Canada, when using the SIG indicator. Variation in future possible distributions of Ae. albopictus was greater amongst the climatic indicators used than amongst the RCM experiments.

Conclusions

Current Ae. albopictus distributions were well predicted by simple climatic indicators and northward range expansion was predicted for the future with climate change. However, current and future predicted geographic distributions of Ae. albopictus varied amongst the climatic indicators used. Further field studies are needed to assess which climatic indicator is the most accurate in predicting regions suitable for Ae. albopictus survival in North America.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-014-0532-4) contains supplementary material, which is available to authorized users.

Mosquito surveillance revealed lagged effects of mosquito abundance on mosquito-borne disease transmission: a retrospective study in Zhejiang, China

Mosquito-borne diseases (MBDs) are still threats to public health in Zhejiang. In this study, the associations between the time-lagged mosquito capture data and MBDs incidence over five years were used to examine the potential effects of mosquito abundance on patterns of MBDs epidemiology in Zhejiang during 2008–2012. Light traps were used to collect adult mosquitoes at 11 cities. Correlation tests with and without time lag were performed to investigate the correlations between MBDs incidence rates and mosquito abundance by month. Selected MBDs consisted of Japanese encephalitis (JE), dengue fever (DF) and malaria. A Poisson regression analysis was performed by using a generalized estimating equations (GEE) approach, and the most parsimonious model was selected based on the quasi-likelihood based information criterion (QICu). We identified five mosquito species and the constituent ratio of Culex pipiens pallens, Culex tritaeniorhynchus, Aedes albopictus, Anopheles sinensis and Armigeres subalbatus was 66.73%, 21.47%, 6.72%, 2.83% and 2.25%, respectively. The correlation analysis without and with time lag showed that Culex mosquito abundance at a lag of 0 or 1 month was positively correlated with JE incidence during 2008–2012, Ae. albopictus abundance at a lag of 1 month was positively correlated with DF incidence in 2009, and An. sinensis abundance at a lag of 0–2 months was positively correlated with malaria incidence during 2008–2010. The Poisson regression analysis showed each 0.1 rise of monthly mosquito abundance corresponded to a positive increase of MBD cases for the period of 2008–2012. The rise of mosquito abundance with a lag of 0–2 months increased the risk of human MBDs infection in Zhejiang. Our study provides evidence that mosquito monitoring could be a useful early warning tool for the occurrence and transmission of MBDs.

First epidemiological report of feline heartworm infection in the Barcelona metropolitan area (Spain)

Background

The metropolitan area of Barcelona is the most densely populated metropolitan area on the Mediterranean coast. Several studies have reported the presence of canine heartworm disease in this region; however, there are no published epidemiological data regarding feline heartworm in this region and the prevalence in this species remains unknown.

Methods

Serum samples from 758 cats living in the metropolitan area of Barcelona (Spain) were collected between 2012 and 2013. To establish the seroprevalence of heartworm infection in cats, serological techniques for anti-D.immitis and anti-Wolbachia antibody detection were used while a commercial ELISA test kit was used to detect circulating D.immitis antigens.

Results

Of these samples, 11.47% were positive to D.immitis and Wolbachia surface protein antibodies and 0.26% were positive to D.immitis antigens. The higher antibody seroprevalences were found in the areas that follow the courses of the rivers Llobregat and Anoia (Baix Llobregat 11.5%, Vallés Occidental 13.2%; Barcelonés 11.7%) where humidity and vegetation favour the development of the mosquito vectors. High antibody seroprevalences were also found in the urban areas (Barcelona city 13.1%; Sabadell 15.5%), which demonstrates that city cats are also at risk from D.immitis infection.

Conclusions

Generally, in Spain cats do not receive prophylactic treatment and therefore the risk of infection is higher in this species than in dogs. Adequate prophylactic plans should be implemented in the feline population. This is the first epidemiologic study on feline heartworm infection to be carried out in continental Spain.

Mosquito surveillance for prevention and control of emerging mosquito-borne diseases in Portugal - 2008-2014

Mosquito surveillance in Europe is essential for early detection of invasive species with public health importance and prevention and control of emerging pathogens. In Portugal, a vector surveillance national program-REVIVE (REde de VIgilância de VEctores)-has been operating since 2008 under the custody of Portuguese Ministry of Health. The REVIVE is responsible for the nationwide surveillance of hematophagous arthropods. Surveillance for West Nile virus (WNV) and other flaviviruses in adult mosquitoes is continuously performed. Adult mosquitoes-collected mainly with Centre for Disease Control light traps baited with CO2-and larvae were systematically collected from a wide range of habitats in 20 subregions (NUTS III). Around 500,000 mosquitoes were trapped in more than 3,000 trap nights and 3,500 positive larvae surveys, in which 24 species were recorded. The viral activity detected in mosquito populations in these years has been limited to insect specific flaviviruses (ISFs) non-pathogenic to humans. Rather than emergency response, REVIVE allows timely detection of changes in abundance and species diversity providing valuable knowledge to health authorities, which may take control measures of vector populations reducing its impact on public health. This work aims to present the REVIVE operation and to expose data regarding mosquito species composition and detected ISFs.