Avia-GIS (Belgium)

BackgroundDirofilaria immitis is a mosquito-transmitted filarial parasite causing heartworm disease in dogs. The parasite may cause a significant disease burden to the dog population in high prevalence areas and is mainly managed through prophylactic treatments.MethodsIn this modelling study, the effect of a prophylactic treatment with moxidectin and sarolaner on heartworm disease dynamics was investigated in dogs. A compartmental model was developed to investigate different epidemiological settings considering different values for prevalence and host preference.ResultsWhen the mosquito host preference to dogs is low, a treatment compliance of only 40% decreases the proportion of infectious dogs. When the host preference of the mosquitoes however increases, an exponential increase in infectious dogs was observed, and a higher treatment compliance is required. In high transmission environments, with a high prevalence and a high mosquito host preference, a high treatment compliance (up to 100%) is required to have an impact on the number of infected animals. Notably, in scenarios with higher host preference towards dogs, more mosquitoes are exposed to sarolaner through the blood meal, leading to higher mortality of these mosquitoes and resulting in fewer infected and infectious dogs.ConclusionsThe preventive efficacy, as measured by the number of non-infected dogs, increases with increasing treatment compliance, but the extent of the treatment effect differs with the epidemiological setting. Adding sarolaner to a heartworm prevention has a complimentary impact on mosquito survival and heartworm disease transmission, although this effect depends on the epidemiological settings, emphasizing the true complexity of disease dynamics of a vector-borne disease.Graphical abstract

The Asian tiger mosquito, Aedes albopictus, is an invasive vector species. It is capable of transmitting more than 20 arboviruses, and is responsible for chikungunya, dengue, and zika transmission. Urbanisation, globalisation, and climate change are expected to expand its habitable range and increase the global vector-borne disease burden in the coming decades. To plan effective control strategies, early-warning and decision support systems are urgently needed.We developed a climate- and environment-driven population dynamics model of Aedes albopictus with extensive geospatial applicability. The foundation of the model is the age- and stage-structured population dynamics model of Erguler et al. (2016)1. We replaced its rainfall- and human population density-dependent breeding site component with a large-scale mechanistic ecological model. The extension effectively created an ecological-dynamic model hybrid capable of representing niche dependence and response to changing environmental and meteorological conditions over time and under various land characteristics. To the best of our knowledge, this is the first spatiotemporal mechanistic model developed with a capacity to learn from both vector presence and longitudinal abundance data.We calibrated the model with an extensive field surveillance dataset by combining the data collected through the AIMSurv project, the first pan-European harmonized surveillance of Aedes invasive mosquito species of relevance for human vector-borne diseases, and the global surveillance records available from VectorBase MapVEu. By deriving the model structure and environmental dependencies from the literature and allowing a complete re-configuration of the entire parameter set, we asserted the biological relevance and geospatial applicability, which extends over Europe and North America.We corroborate that temperate northern territories are becoming increasingly suitable for Aedes albopictus establishment, while neighbouring southern territories become less suitable, as climate continues to change. We identify potential hotspots over Europe and North America by employing the combination of vector abundance and activity as a proxy to pathogen transmission risk.  By investigating routes of introduction to new territories, we demonstrate the significant role of dynamic environmental suitability in the highly efficient spread of this invasive mosquito.The model is scheduled for integration into the "Climate-driven vector-borne disease risk assessment platform", to predict habitat suitability and dynamic abundance of important disease vectors and the risk of diseases transmitted by them at any location and time up to the end of the century. With the continental model of Aedes albopictus, the platform will reliably inform public health professionals and policy makers and contribute to the global strategies of integrated vector management.1 Erguler K, Smith-Unna SE, Waldock J, Proestos Y, Christophides GK, Lelieveld J, Parham PE. Large-scale modelling of the environmentally-driven population dynamics of temperate Aedes albopictus (Skuse). PloS one. 2016 Feb 12;11(2):e0149282.

Vegetation is a climate modifier: It is a primary modifier, such as the Amazon rain forest, or secondary modifier, such as the agricultural fields of Pannonian lowlands in Central Europe. At periods of winter crop spring renewal and the start of the orchard growing season, enhanced evapotranspiration shifts energy balance partitions from sensible toward latent heat flux. This surface flux alteration converges into the boundary layer, and it can be detected in the daily variations of air temperature and humidity as well as daily temperature range records. The time series of micrometeorological measurements and phenological observations in dominant plant canopies conducted by Forecasting and Reporting Service for Plant Protection of the Republic of Serbia (PIS) are explored to select indices that best record the signatures of plant growth stages in temperature and humidity daily variations. From the timing of extreme values and inflection points of relative humidity (R1 and R2) and normalized daily temperature range (DTR/Td), we identified the following stages: (a) start of flowering (orchard)/spring start of the growing season (crop), (b) full bloom (orchard)/development (crop), (c) maximum LAI reached/yield formation (orchard and crop), and (d) start of dormancy (orchard)/leaf drying (crop). The average day of year (DOY) for dominant plants corresponds to the timing obtained from climatological time series recorded on a representative climate station.

BackgroundCulicoides biting midges transmit viruses resulting in disease in ruminants and equids such as bluetongue, Schmallenberg disease and African horse sickness. In the past decades, these diseases have led to important economic losses for farmers in Europe. Vector abundance is a key factor in determining the risk of vector-borne disease spread and it is, therefore, important to predict the abundance of Culicoides species involved in the transmission of these pathogens. The objectives of this study were to model and map the monthly abundances of Culicoides in Europe.MethodsWe obtained entomological data from 904 farms in nine European countries (Spain, France, Germany, Switzerland, Austria, Poland, Denmark, Sweden and Norway) from 2007 to 2013. Using environmental and climatic predictors from satellite imagery and the machine learning technique Random Forests, we predicted the monthly average abundance at a 1 km2 resolution. We used independent test sets for validation and to assess model performance.ResultsThe predictive power of the resulting models varied according to month and the Culicoides species/ensembles predicted. Model performance was lower for winter months. Performance was higher for the Obsoletus ensemble, followed by the Pulicaris ensemble, while the model for Culicoides imicola showed a poor performance. Distribution and abundance patterns corresponded well with the known distributions in Europe. The Random Forests model approach was able to distinguish differences in abundance between countries but was not able to predict vector abundance at individual farm level.ConclusionsThe models and maps presented here represent an initial attempt to capture large scale geographical and temporal variations in Culicoides abundance. The models are a first step towards producing abundance inputs for R0 modelling of Culicoides-borne infections at a continental scale.

Abstract Background The tsetse-transmitted African trypanosomiases affect humans and animals. Trypanosoma. brucei rhodesiense sleeping sickness, or human African trypanosomiasis is a zoonosis, for which cattle are the main reservoir of infection in south-eastern Uganda. Transmission of human and animal infective trypanosomes can be reduced by the application of deltamethrin insecticide to the belly and legs of cattle, thus reducing tsetse fly populations. Alongside an epidemiological study in southeastern Uganda, a farm level assessment was done to calculate the average and incremental benefit-cost ratios of spraying different proportions of the village cattle population using this restricted application protocol.Method A study comprising 2,400 semi-structured interviews was undertaken over a period of 18 months. Financial data on household income and expenditure on cattle provided the basis for the marginal analyses. The benefit of RAP to farmers was assessed using gross margin analysis whereas the costs were obtained from expenses incurred by farmers in participating in the RAP intervention. Subsequently, the RAP intervention villages were compared with a control village to determine the average and incremental benefit-cost ratio across all households.Results The benefit-cost analysis of spraying 25%, 50% and 75% of the cattle population yielded benefit-cost ratios of 6.22, 5.56 and 4.46. The incremental benefit-cost ratios from spraying each additional 25% of the population cattle were 14.32, 3.97 and 0.79 respectively, showing a very high return on investment in spraying 25% of the population, with returns reducing thereafter.Conclusion Comparing the gross margins per bovine of applying RAP to different proportions of the cattle population to a pre-intervention situation and a control, the study found that increasing the proportion of cattle sprayed yielded increasing benefits to farmers, but that these benefits were subject to diminishing returns. Given the high proportion of draft males in the cattle population (37%) their important contribution to livestock output and farmers’ preference for treating these animals, from a practical viewpoint this study recommends spraying only draft cattle to control trypanosomiasis in this area, although in areas or households with a lower proportion of draft males, farmers could be advised to also include cows.

An emerging field for environmental wireless sensor networks (WSN) is entomological vector surveillance. Sensor technology can be used to shoulder ecologically friendly practices within the integrated pest management (IPM) approach. Proper surveillance and subsequent modelling of the impact that pest and disease have on human health and crop agriculture is a pressing issue in numerous segments. Complex numerical models are being developed to generate information regarding the population dynamics of vector species and the expected circulation of vector-borne disease (VBD). These models require detailed micrometeorological forcing representative of the vector habitat to generate accurate simulations. Near real-time data offload in remote areas with flexible channels of communication for complex and heterogeneous topographies is an important component in this type of application. In this chapter, the authors provide an overview of the scope and best-practice approaches in applying WSN technology to drive IPM models.

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.

This joint ECDC-EFSA report assesses whether vector count data (abundance) and the way these change throughout the year (seasonality) can provide useful information about vector-borne diseases epidemiological processes of interest, and therefore, whether resources should be devoted to collecting such data. The document also summarises what measures of abundance and seasonality can be collected for each vector group (mosquitoes, sandflies, midges and ticks), lists the gaps in the sampling coverage and provides guidance for prioritising the acquisition of information. Knowing where vector species occur is crucial for the assessment of vector-borne disease risk. Collecting abundance and seasonality data through field sampling is, however, more expensive and time consuming than collecting most other vector-related data. The importance of abundance and seasonality data varies considerably according to the vector group and the epidemiological concept of interest. Epidemiological concepts of tick-borne disease are less informed by abundance data than are those of the other vector groups, and presence/absence data of ticks may be sufficient in conjunction with other factors. Abundance data are generally considered relevant to pathogen establishment and transmission but less useful to inform early warning systems, estimates of the likelihood of pathogen persistence and –for sandflies, midges and ticks– to inform targeting of control measures. The conclusions on this report were based on VectorNet group discussions, field sampling studies, and review of both peer-reviewed and grey literature. VectorNet is a European network for gathering and sharing data on the geographic distribution of arthropod vectors of disease agents affecting humans and livestock. Finally, the report notes that any form of extensive vector sampling depends not only on resources to fund the sampling programmes, but also on the availability of entomologists that have the skills to implement surveillance and monitoring programmes.

The Asian tiger mosquito, Aedes albopictus, is one of the world’s most dangerous invasive species. It has vector competence for a wide range of arboviruses such as chikungunya, dengue, Zika and Rift Valley fever viruses. The vector originated in Asia but has recently spread to the temperate regions of Europe and North America. Further spread to the north and the east and a shift to higher altitudes could be expected as a result of climate change. This makes modelling the regional climatic suitability for the establishment of A. albopictus in naive regions a pressing issue. The future suitability and subsequent seasonal activity of the vector were investigated using three mechanistic models, with climatic data from the Eta Belgrade University-Princeton Ocean Model regional climate model. The results showed that after a slight decrease in suitability for the first part of the century, most of Serbia would become significantly more suitable for the establishment of A. albopictus. This is due to the simulated rise in seasonal and annual temperatures by the end of the twenty-first century. This study allows for the incorporation of regional heterogeneity in vector modelling. The spatial resolution of the maps obtained from a regional analysis is much higher than that acquired by a global model, allowing for detailed risk assessment and planning of surveillance focused on the habitats where the main introduction routes and climatic suitability are coupled. This work should be applied to all countries in the region with the risk of introduction or further spread of A. albopictus.

BackgroundThe public and private sector in the EU spend around €800 million per year on animal health and welfare related research. An objective process to identify critical gaps in knowledge and available control tools should aid the prioritisation of research in order to speed up the development of new or improved diagnostics, vaccines and pharmaceuticals and reduce the burden of animal diseases.MethodHere, we describe the construction of a database based on expert consultation for 52 infectious diseases of animals.ResultsFor each disease, an expert group produced a disease and product analysis document that formed the basis for gap analysis and prioritisation. The prioritisation model was based on a closed scoring system, employing identical weights for six evaluation criteria (disease knowledge; impact on animal health and welfare; impact on public health; impact on wider society; impact on trade; control tools). The diseases were classified into three groups: epizootic diseases, food-producing animal complexes or zoonotic diseases.DiscussionThe highly ranked diseases in the prioritisation model comprised mostly zoonotic and epizootic diseases with important gaps identified in vaccine development and pharmaceuticals, respectively. The most important outcome is the identification of key research needs by disease. The rankings and research needs by disease are provided on a public website (www.discontools.eu) which is currently being updated based on new expert consultations. ConclusionAs such, it can become a reference point for funders of research including the European Commission, member states, foundations, trusts along with private industry to prioritise research. This will deliver benefits in terms of animal health and welfare but also public health, societal benefits and a safe and secure food supply.