Emergence Of Bluetongue Research Articles

Climate change and vector-borne diseases

Vector-borne diseases (VBD), such as Zika, dengue, chikungunya, yellow fever, leishmaniasis, malaria, Rift Valley Fever, Lyme disease and bluetongue are transmitted by exothermic arthropod vectors such as mosquitoes, flies, midges and ticks that do not regulate their internal temperature. Precipitation provides breeding sites for the early larval stages of the vectors, while temperature modulates their development, mortality rate and the time required for the pathogen to replicate in their body. As a consequence, climate change in addition to an ever-increasing mobility of goods and people and other socio-economic risk factors, will very likely affect the distribution of vector-borne diseases in future. Coupling mathematical disease models with climate observations and ensemble of future climate change scenarios, allow to explore potential future changes in VBD distribution and assess related uncertainties. This presentation will review research carried out at the University of Liverpool in collaboration with several international partners over the past decade. Our work confirmed the impact of the 2006 heatwave on the emergence of bluetongue, a midge-borne disease affecting ruminants, into northern Europe. In 2011 another publication anticipated the northward spread of Aedes albopictus, the Asian tiger mosquito, in Europe and into southern UK. In a study published in 2014 we showed that malaria risk could increase over tropical altitude regions while it could decrease over the warmer regions during the 2080s under the most extreme RCP8.5 scenario. In 2017, a study showed that the climatic conditions related to the 2015 El Niño event favoured the Zika outbreak that had a large impact on Latin America that year. Many other research groups anticipated the spread of vectors and the diseases they can transmit worldwide. This fact demonstrates the value and usefulness of such predictive risk models; and importantly that we need to take urgent measures to tackle anthropogenic climate change.

Update of the Culicoides (Diptera: Ceratopogonidae) species checklist from Algeria with 10 new records

BackgroundThe Culicoides fauna of Algeria has been historically investigated, leading to the description of many new species by Kieffer in the 1920s, Clastrier in the 1950s or Callot in the 1960s and to a comprehensive inventory by Szadziewski in the 1980s. The emergence of bluetongue in the late 1990s enhanced Culicoides collections made in the country over the last two decades, but information remained mostly unpublished. The aim of this study is therefore to provide a comprehensive and updated checklist of Culicoides biting midge species in Algeria.MethodsThe literature (published and grey, in French and in English) from 1920 to date on Culicoides collections in Algeria was collected and analyzed in the light of the current taxonomic and systematic knowledge and methods. Fresh Culicoides material was also analyzed using light/suction trap collections carried out from November 2015 to September 2018 in nine localities of the ‘wilayah’ of Tiaret (northwestern Algeria). Slide mounted specimens were identified morphologically using the interactive identification key IIKC and original descriptions. Specimens were then compared with non-type material originating from different countries and partly with type material.ResultsA total of 13,709 Culicoides, belonging to at least 36 species within 10 subgenera, were examined leading to 10 new records in Algeria, including C. chiopterus, C. dewulfi, C. navaiae, C. grisescens, C. paradoxalis, C. shaklawensis, C. simulator, C. univittatus, C. achrayi and C. picturatus. These new records and all previous records provided by the literature review were discussed.ConclusionsWe propose a Culicoides checklist for the Algerian fauna of 59 valid species, including species mainly with a large Palaearctic distribution and a specific Mediterranean distribution, and only a few species from the Afrotropical region. Among them, several species, mainly of the subgenera Avaritia and Culicoides, are confirmed or probable vectors of arboviruses important in animal health.

Longitudinal monitoring of Culicoides in Belgium between 2007 and 2011: local variation in population dynamics parameters warrant cautious use of monitoring data

BackgroundSeveral European countries suffered important economic losses during the past decade due to the emergence of bluetongue and Schmallenberg viruses. Both are viruses of veterinary importance and are spread by Culicoides spp. This triggered many European countries to start Culicoides population monitoring. Recently a one year monitoring study at 16 sites in Belgium revealed that important variation existed in Culicoides abundance and species diversity between collection sites. In order to analyze whether this variation is consistent over years, a detailed analysis of monitoring data collected at seven locations in Belgium between 2007 and 2011 was performed in this study. At all locations, biting midges were collected with OVI black light traps set-up in close proximity to livestock.ResultsIn total, 42 different Culicoides species were morphologically identified. Species of the subgenus Avaritia represented 83% of all collected midges. Nevertheless, important differences in species composition were found between sites. Furthermore, statistical differences between sites were found for the total and maximum annual abundance, showing that a consistent higher or lower number of Culicoides could be collected depending on the selected collection site. Yearly, up to 16 and 30-fold differences in total and maximum annual abundances between sites, respectively, were found. Also the month in which most Culicoides were collected varied greatly between years, both at local (from May to October) and country level [May (2008), June (2010), July (2009), August (2011), October (2007)]. Finally, the average vector-free period over all sites and years was 173 days and could roughly be defined between November and the end of April. Interestingly, important yearly variations of up to two months in the duration of the vector-free period were found between the studied collection sites. In contrast to the abundance parameters, no specific sites could however be identified where monitoring consistently showed shorter or longer vector-free periods.ConclusionsIn conclusion, our results show that the selection of collection sites for Culicoides monitoring, even in a small country such as Belgium, strongly influences abundance parameters and that yearly variation in seasonality occurs. This emphasizes that care should be taken when using such parameters in risk assessments for transmission of Culicoides-borne diseases and that more clear and strict guidelines for Culicoides monitoring should be considered when monitoring data are used for legislative purposes.

Émergence et ré-émergence de deux dangers sanitaires de catégorie 1 en France (FCO) et à Maurice (FA)

Emergence and re-emergence of two major diseases in France (bluetongue) and in Mauritius (foot-and-mouth). The emergence of Bluetongue (BT) in continental France (caused by virus of serotype 8 (BTV-8) in 2006 and virus of serotype 1 (BTV-1) in 2007) was a total surprise. End of 2012, six years after the introduction of BT, France was declared free from this disease. However, at the end of August 2015, the BTV-8 made its reappearance in the center of France. In 2016, our laboratory re-isolated this virus. In Corsica, a virus of serotype 4 was identified on 1st December 2016 from sheep samples. On another hand, in 2016, we identified a virus of Foot-and-Mouth disease serotype O in Mauritius. This presentation will describe the conditions of the detection of these viruses as well as the results of phylogenetic analyzes.

Defining an emerging disease.

Defining an emerging disease is not straightforward, as there are several different types of disease emergence. For example, there can be a 'real' emergence of a brand new disease, such as the emergence of bovine spongiform encephalopathy in the 1980s, or a geographic emergence in an area not previously affected, such as the emergence of bluetongue in northern Europe in 2006. In addition, disease can emerge in species formerly not considered affected, e.g. the emergence of bovine tuberculosis in wildlife species since 2000 in France. There can also be an unexpected increase of disease incidence in a known area and a known species, or there may simply be an increase in our knowledge or awareness of a particular disease. What all these emerging diseases have in common is that human activity frequently has a role to play in their emergence. For example, bovine spongiform encephalopathy very probably emerged as a result of changes in the manufacturing of meat-and-bone meal, bluetongue was able to spread to cooler climes as a result of uncontrolled trade in animals, and a relaxation of screening and surveillance for bovine tuberculosis enabled the disease to re-emerge in areas that had been able to drastically reduce the number of cases. Globalisation and population growth will continue to affect the epidemiology of diseases in years to come and ecosystems will continue to evolve. Furthermore, new technologies such as metagenomics and high-throughput sequencing are identifying new microorganisms all the time. Change is the one constant, and diseases will continue to emerge, and we must consider the causes and different types of emergence as we deal with these diseases in the future.

Bluetongue Virus Detection by Real-Time RT-PCR inCulicoidesCaptured During the 2006 Epizootic in Belgium and Development of an Internal Control

After the emergence of bluetongue (BT) in Belgium in 2006, two types of entomological surveys were initiated, the one to identify the local vector species, and the other to study their population dynamics. In the vector study, Culicoides were captured near farms with recently infected cattle or sheep; in the population study Culicoides were captured in two meadows situated in the BT-affected region. A total of 130 pools of parous, non-blood engorged female midges (with a mean of 7.5 midges per pool) were analysed with real-time reverse transcription PCR (RT-qPCR) targeting bluetongue virus (BTV) segment 5. To ensure the RNA integrity of the samples, all pools were also tested in a second RT-qPCR targeting Culicoides 18S rRNA, which served as an internal control. Seventeen pools with negative results for both 18S and BTV were excluded, most of which originated from the population survey. In the vector survey near outbreak sites, female midges of the obsoletus complex, including C. obsoletus, C. scoticus, C. dewulfi and C. chiopterus, dominated the black-light trap collections with 19 of 89 pools being BTV-positive. Moreover, all the collections from the vector survey included at least one positive pool of the obsoletus complex compared with only 20% collections (C. obsoletus/C. scoticus) in the population survey. The current study also revealed the presence of BTV RNA in one of five pools of C. pulicaris females captured near recent BT outbreaks, suggesting that this species might have played a role in transmission. Finally, the use of RT-qPCR for the recognition of new potential BTV vector species and the impact of an appropriate monitoring method and internal control are discussed.

Regulatory issues surrounding the temporary authorisation of animal vaccination in emergency situations: the example of bluetongue in Europe

A marketing authorisation for a veterinary vaccine is granted after the quality, safety and efficacy of the product have been assessed in accordance with legal standards. The assessment includes complete characterisation and identification of seed material and ingredients, laboratory and host animal safety and efficacy studies, stability studies, and post-licensing monitoring of field performance. This assessment may not be possible during the emergence of a new animal disease, but several mechanisms exist to allow for the availability of products in an emergency animal health situation, e.g. autogenous biologics, conditional licences, experimental and emergency use authorisations, the importation of products in use elsewhere in the world and pre-approved vaccine banks. Using the emergence of bluetongue in northern Europe as an example, the regulatory issues regarding the temporary authorisation of animal vaccination are described. Several conditions must be fulfilled before a temporary authorisation can be granted, e.g. inactivated vaccines should be used in order to exclude reversion to virulence and reassortment between vaccine viruses and/or field strains of the bluetongue virus; decision-making must be supported by scientific evidence and risk analysis; there must be a complete census of the susceptible animals that were vaccinated; vaccination protocols must be adhered to and there must be a scheme allowing for registration, delivery and follow-up of vaccination, and monitoring, analysis and, possibly, adjustment of field use of the vaccination. This temporary authorisation must be replaced by a full authorisation as quickly as possible.