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Rift Valley fever (RVF) is one of the many zoonotic arboviral haemorrhagic fevers present in Africa. The ability of the pathogen to persist in multiple geographically distinct regions has raised concerns about its potential for spread to and persistence within currently disease-free areas. However, the mechanisms for which RVF virus persistence occurs at both local and broader geographical scales have yet to be fully understood and rigorously quantified. Here, we developed a mathematical metapopulation model describing RVF virus transmission in livestock across the four islands of the Comoros archipelago and fitted this model in a Bayesian framework to surveillance data conducted in livestock across those islands between 2004 and 2015. In doing so, we estimated the importance of island-specific environmental factors and animal movements between those islands on the persistence of RVF virus in the archipelago, and we further tested the impact of different control scenarios on reducing disease burden. We demonstrated that the archipelago network was able to sustain viral transmission over 10 years after assuming only one introduction event during early 2007. Movement restrictions were only useful to control the disease in Anjouan and Mayotte, as Grande Comore and Mohéli were able to self-sustain RVF viral persistence, probably due to local environmental conditions that are more favourable for vectors. We also evidenced that repeated outbreaks during 2004-2020 may have gone under-detected by local surveillance in Grande Comore and Mohéli. Strengthened longterm and coordinated surveillance would enable the detection of viral re-emergence and evaluation of different relevant vaccination programmes.

Capripoxviruses (CaPVs) have been shown to be ideal viral vectors for the development of recombinant multivalent vaccines to enable delivery of immunogenic genes from ruminant pathogens. So far, the viral thymidine kinase (TK) gene is the only gene used to generate recombinants. A putative non-essential gene encoding a G-protein-coupled chemokine receptor subfamily homologue (GPCR) was targeted as an additional insertion site. Peste des petits ruminants (PPR) was chosen as a disease model. A new recombinant CaPV expressing the viral attachment hemagglutinin (H) of the PPR virus (PPRV) in the GPCR insertion site (rKS1-HPPR-GPCR) was generated in the backbone North African isolate KS1 strain of lumpy skin disease virus (LSDV). Comparison with the recombinant CaPV expressing the H of PPRV in the TK gene (rKS1-HPPR-TK) shown to induce protection against both PPR and LSD in both sheep and goats was assessed. The suitability of the GPCR gene to be a putative additional insertion site in the CaPV genome is evaluated and discussed.

International audience; East Coast fever (ECF), one of the most serious tick-borne diseases in sub-Saharan and eastern Africa, was introduced to the island of Grande Comore in 2002 through zebu import from Tanzania, resulting in at least a 10% loss of livestock. A participatory epidemiology initiative was launched in 2015 to gain a better understanding of ECF epidemiology. Thirty-six villages were investigated involving 36 focus group sessions and 120 individual questionnaires. Farmers' knowledge of ECF and of priority diseases affecting the country was assessed, and the impacts of ECF and other major diseases were compared by a scoring method. The results showed that 69.4% (95% CI [51.3, 87.5%]) of the farmers had good to very good knowledge of ECF. The most important cattle diseases on Grande Comore were considered to be East Coast fever, heartwater, babesiosis, and cutaneous diseases. About 58% of the farmers (95% CI [49.2, 66.8%]) use curative treatments when cattle were sick. Between January and September 2015, the ECF incidence was estimated at 18.5% (95% CI [15.5, 21.4%]), and 87.5% (95% CI [72.7, 100%]) of the cattle infected by ECF died. The ECF incidence estimated in our study was found to be less when compared to that observed in Tanzania even though the climatic conditions in the Union of the Comoros are suitable for the biological vector of ECF, the tick species Rhipicephalus appendiculatus. Access to chemical treatment and its effectiveness against ECF, as well as controlling borders and organizing quarantine, are discussed.

International audience; Major explosive outbreaks of Rift Valley fever (RVF), an arthropod borne zoonotic disease, occur in humans and animals with significant mortality and economic impact across continental Africa and the Indian Ocean region (Madagascar, the Comoros archipelago). Recently, sporadic human cases have been reported in Mayotte and Grande Comore, two islands belonging to the Comoros archipelago. To identify the hypothetical source of virus introduction in an inter-epidemic or a post-epidemic period, a longitudinal survey of livestock was set up in Comorian ruminant populations, known to be susceptible hosts. The phylogeographic genomic analysis has shown that RVF virus (RVFV) detected in a zebu collected in Anjouan in August 2011 seems to be related to the last known epidemic of RVF which occurred in East Africa and Madagascar (2007–2009). This result highlights the fact that RVFV is maintained within local livestock populations and transboundary animal movements from eastern continental Africa to Indian Ocean islands likely result in RVFV crossover.

International audience; Currently, there are no worldwide licensed vaccines for Rift Valley fever (RVF) that are both safe and effective. Development and evaluation of vaccines, diagnostics and treatments depend on the availability of appropriate animal models. Animal models are also necessary to understand the basic pathobiology of infection. Here, we report the use of an inbred MBT/Pas mouse model that consistently reproduces RVF disease and serves our purpose for testing the efficacy of vaccine candidates; an attenuated Rift Valley fever virus (RVFV) and a recombinant RVFV-capripoxvirus. We show that this model is relevant for vaccine testing.

A high level of serum IgE is generally associated with human resistance to schistosomes, though the protective mechanisms of IgE remain undefined. We recently reported that whereas some individuals who are occupationally hyperexposed to Schistosoma mansoni display resistance to reinfection, others remain highly susceptible, in some cases due to HIV-1 co-infection. As IgE functions, in part, through FcepsilonRI on mast cells, we characterized circulating CD117(+) FcepsilonRI(+) mast cell precursors in this population. Surprisingly, a higher percentage of CD117(+) cells correlated with a susceptible phenotype in HIV-1 seronegative participants with schistosomiasis. There was no association between percentages of peripheral CD117(+) cells and susceptibility to reinfection in persons with HIV-1. Serum levels of polyclonal IgE were inversely correlated with percentages of CD117(+) cells regardless of HIV-1 status. Thus, immature mast cells may affect IgE availability, or IgE may affect immature mast cells, altering the balance of host susceptibility and resistance to schistosomes.

International audience; In order to study the safety and the immunogenicity of the South African vaccine against the serotype 2 bluetongue virus, two groups of seven sheep were vaccinated with the vaccine used in the French island of Corsica. Vaccinated and nonvaccinated sheep were observed clinically and their rectal temperatures were recorded daily. The serological response in vaccinated animals confirmed the immunogenicity of the vaccine. Post-vaccinal viraemia was investigated and the vaccine genome was detected by reverse transcription polymerase chain reaction (RT-PCR). No viraemia was observed at post-vaccination days 4, 7 and 11 but the vaccine strain of virus was detected by RT-PCR throughout the experiment. The thermostability of the vaccine was also evaluated. The vaccine titre strongly decreased at temperatures higher than 35 degreesC.

Antibodies against bluetongue virus were detected in cattle, sheep, goats, and camels in Algeria in 2008. Antibodies against epizootic hemorrhagic disease virus were detected in cattle, but antibodies against African horse sickness virus were not detected in horses and mules. Epizootic hemorrhagic disease in northern Africa poses a major risk for the European Union.

International audience; Bluetongue virus (BTV) and epizootic haemorrhagic disease virus (EHDV) are members of the Orbivirus genus of the Reoviridae family transmitted between ruminants by the bites of Culicoides midges. BTV went undetected in Reunion Island between its first documented emergence in 1979 and two other serious outbreaks with both BTV-3 and EHDV-6 in 2003, and both EHDV-6 and BTV-2 in 2009. In these outbreaks, infected animals developed symptoms including hyperthermia, anorexia, congestion, prostration and nasal discharge. Samples were collected in 2011 to assess the prevalence of BT and EHD in ruminants native to Reunion Island by serological analysis. A cross-sectional study was undertaken on 67 farms, including a total of 276 cattle, 142 sheep and 71 goats. The prevalence rates of BT and EHD were 58% (95% CI [54.03-62.94]) and 38% (95% CI [33.85-42.63], respectively. Two further suspected outbreaks were confirmed to involve EHDV and BTV/EHDV. A new circulating EHDV serotype 1 of unknown origin was isolated. Our results confirm that the prevalence of both BT and EHD is high and that both are likely currently circulating. A high risk of BTV and EHDV infections was associated with the introduction of ruminants from neighbouring farms without quarantine, the presence of organic and other waste on the farm, and treatment against ectoparasites and insects.

Human and animal serological surveys suggest that West Nile virus (WNV) circulation is widely distributed in Madagascar. However, there are no reported West Nile fever outbreaks or epizootics in the country and only one fatal human case has been reported to date. Currently there is very limited information on the maintenance and the transmission of WNV in Madagascar and particularly on the mosquito species involved in transmission cycles. In 2014, we initiated a study to investigate mosquito species composition, relative abundance, and trophic behavior in Mitsinjo District close to Lake Kinkony, a WNVendemic area in north-western Madagascar. We collected a total of 2519 adult mosquitoes belonging to 21 different species. The most abundant species was Aedeomyia (Aedeomyia) madagascarica Brunhes, Boussès & da Cunha Ramos, which made up 83% of all the mosquitoes collected. Mosquito abundance was associated with proximity to the lake (Morafeno and Ankelimitondrotra). Additionally, a correlation was observed between the lake-side biotope and the abundance of mosquito vectors in Morafeno. WNV RNA was detected in one pool of Ae. madagascarica and one pool of Anopheles (Cellia) pauliani Grjebine, suggesting that these two species may be involved in the maintenance and/or transmission of WNV in Madagascar.; – Human and animal serological surveys suggest that West Nile virus (WNV) circulation is widely distributed in Madagascar. However, there are no reported West Nile fever outbreaks or epizootics in the country and only one fatal human case has been reported to date. Currently there is very limited information on the maintenance and the transmission of WNV in Madagascar and particularly on the mosquito species involved in transmission cycles. In 2014, we initiated a study to investigate mosquito species composition, relative abundance, and trophic behavior in Mitsinjo District close to Lake Kinkony, a WNV endemic area in northwestern Madagascar. We collected a total of 2519 adult mosquitoes belonging to 21 different species. The most abundant species was Aedeomyia (Aedeomyia) madagascarica Brunhes, Boussès & da Cunha Ramos, which made up 83% of all the mosquitoes collected. Mosquito abundance was associated with proximity to the lake (Morafeno and Ankelimitondrotra). Additionally, a correlation was observed between the lake-side biotope and the abundance of mosquito vectors in Morafeno. WNV RNA was detected in one pool of Ae. madagascarica and one pool of Anopheles (Cellia) pauliani Grjebine, suggesting that these two species may be involved in the maintenance and/or transmission of WNV in Madagascar. Résumé – Dynamique des populations des espèces de moustiques dans une zone d'endémie du virus de la fièvre du Nil Occidental à Madagascar. Des études sérologiques humaines et animales suggèrent que la circulation du virus de la fièvre du Nil Occidental (VNO) est largement répandue à Madagascar. Toutefois, il n'existe pas de foyers de VNO ni d'épizooties dans le pays et seul un cas humain mortel a été signalé à ce jour. Actuellement, on dispose de très peu d'informations sur l'entretien et la transmission du VNO à Madagascar et en particulier sur les espèces de moustiques impliquées dans les cycles de transmission. En 2014, nous avons entrepris une étude pour étudier la composition des espèces de moustiques, l'abondance relative et le comportement trophique dans le district de Mitsinjo près du lac Kinkony, une zone endémique du VNO dans le nord-ouest de Madagascar. Nous avons recueilli un total de 2519 moustiques adultes appartenant à 21 espèces différentes. L'espèce la plus abondante était Aedeomyia (Aedeomyia) madagascarica Brunhes, Boussès & da Cunha Ramos, qui constituait 83 % de tous les moustiques collectés. L'abondance de moustiques était associée à la proximité du lac (Morafeno et Ankelimitondrotra). De plus, une corrélation a été observée entre le biotope bordure du lac et l'abondance de moustiques vecteurs à Morafeno. De l'ARN du VNO a été détecté dans un pool d'Ae. madagascarica et un pool d'Anopheles (Cellia) pauliani Grjebine suggérant que ces deux espèces peuvent être impliquées dans le maintien et/ou la transmission du VNO à Madagascar. a These authors contributed equally to this work.

As further confirmation of a first human case of Rift Valley fever in 2007 in Comoros, we isolated Rift Valley fever virus in suspected human cases. These viruses are genetically closely linked to the 2006–2007 isolates from Kenya.

Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) are small hematophagous dipterans responsible for transmitting major viruses to livestock such as African horse sickness virus in equids, and pizootic haemorrhagic disease and bluetongue viruses (BTV) in ruminants. Between 1998 and 2005, BTV outbreaks occurred into many countries around the Mediterranean basin associated with the northward extension of C. imicola, which colonized new Mediterranean territories in the past decades due to the global increase of temperatures. In August 2006, BTV serotype 8 (BTV-8) was unexpectedly introduced in the Netherlands and was intensively transmitted by autochthonous Palaearctic Culicoides species, leading in 2007 and 2008 to a major sanitary crisis in whole continental Europe with huge economic losses due to animal movement restrictions. This chapter presents a synthesis of the data gathered through the different entomological surveillance networks implemented in France since 2000 when C. imicola was recorded for the first time in France. These networks aimed at first to monitor the spread and establishment of the invasive C. imicola and then from 2006 onwards, to study the diversity and dynamics of autochthonous Culicoides species. The data collected enable to describe for the first time the spread of C. imicola into French mainland, propose an updated list of Culicoides species for France, describe the Culicoides species distribution and seasonal dynamics, and report assays to identify BTV in field-collected Culicoides during outbreaks. (Texte intégral)

International audience; This study reports on an outbreak of disease that occurred in central Algeria during July 2006. Sheep in the affected area presented clinical signs typical of bluetongue (BT) disease. A total of 5245 sheep in the affected region were considered to be susceptible, with 263 cases and thirty-six deaths. Bluetongue virus(BTV) serotype 1 was isolated and identified as the causative agent. Segments 2, 7 and 10 of this virus were sequenced and compared with other isolates from Morocco, Italy, Portugal and France showing that they all belong to a ‘western’ BTV group/topotype and collectively represent a western Mediterranean lineage of BTV-1.

In southern Europe, orbiviral diseases such as bluetongue (BT) have been assumed to have been largely transmitted by the classical Afro-Asian vector Culicoides imicola Kieffer (Diptera: Ceratopogonidae). Recent outbreaks have occurred in regions where C. imicola is normally absent, supporting the theory that other species belonging to the Obsoletus or Pulicaris complexes may play a role in BT virus transmission. Investigations of the ecology of the species within the former group are hampered by females of member species being extremely difficult to separate by classical morphology. To allow straightforward separation of these species in France, a multiplex polymerase chain reaction-based on internal transcribed spacer (ITS)-1 rDNA was developed to distinguish between Culicoides chiopterus Meigen, Culicoides dewulfi Goetghebuer, Culicoides montanus Shakirjanova, Culicoides obsoletus Meigen, and Culicoides scoticus Downes & Kettle. This tool will be useful in defining both the vector role and larval biotopes of these species in Europe.

The current microscopy method for identifying the Culicoides imicola Kieffer, 1913 species can be time and labour intensive. There is a need for the development of a rapid and quantitative tool to quantify the biting midges C. imicola ss in light trap catches. A reproducible and sensitive real-time polymerase chain reaction method that targets the internal transcribed spacer (ITS-1) of ribosomal DNA of C. imicola ss species was developed. This real-time PCR assay was first performed on 10-fold serial dilutions of purified plasmid DNA containing specific C. imicola ss ITS-1. It was then possible to construct standard curves with a high correlation coefficient (r2 = 0.99) in the range of 10−2–10−8 ng of purified DNA. The performances of this PCR were evaluated in comparison with morphological determination on Culicoides trapped along the Mediterranean coastal mainland France. ROC statistical analysis was carried out using morphology as gold standard and the area under the ROC curve had a satisfactory value of 0.9752. The results indicated that this real-time PCR assay holds promise for monitoring C. imicola ss population in both surveillance and research programmes because of its good specificity (92%) and sensitivity (95%).

Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) play important roles in the transmission of viral diseases affecting wild and domestic ruminants and horses, including Bluetongue (BT) and African horse sickness (AHS) respectively. In southern Europe, BT has been largely transmitted by the classical Afro-Asian vector Culicoides imicola Kieffer. However, other species such as C. obsoletus Meigen, C. scoticus Downs & Kettle and C. pulicaris Linné may also be involved in BTV transmission. As a consequence of the discovery of C. imicola followed by BTV-2 outbreaks on the island of Corsica in October 2000, further studies on these biting midges have been carried out. To better characterize the evolution and phylogenetic relations of Culicoides, molecular analysis in parallel with a morphology-based taxonomic approach were performed. Phylogenetic analyses of French Culicoides species were undertaken using the ribosomal DNA (rDNA) internal transcribed spacer 1 (ITS1) as a molecular target. This region was shown to be useful in understanding evolutionary and genetic relationships between species. Construction of several trees showed that molecular phylogeny within the genus Culicoides correlates not only with morphological-based taxonomy but also with ecological patterns.

Several serology-based immunoassays are used to diagnose visceral leishmaniasis (VL), a chronic protozoan parasitic disease caused by the Leishmania donovani complex. These tests are primarily designed to diagnose the most severe clinical form of VL, known as kala-azar. However, leishmanial infection is frequently asymptomatic and may manifest only as a positive serologic response or positive leishmanin skin test. We modified a previously described enzyme-linked immunosorbent assay (ELISA) that detects patient antibodies reactive with the recombinant Leishmania protein K39 (rK39) to confirm suspected kala-azar and to detect asymptomatic infection in a community study in Bangladesh. With the inclusion of a standard curve on each ELISA plate, the rK39 ELISA was more repeatable (kappa coefficient of agreement = 0.970) and more reliable compared to the original method (kappa = 0.587, P < 0.001). The cutoff point for a positive antibody response was chosen based on the 99th percentile of the ELISA distribution for the negative-control sera. However, we found that sera from all patients with active kala-azar yielded values more than twice the magnitude of this cutoff. Using receiver-operator characteristic curves, we determined a second cutoff value predictive of kala-azar. Using these criteria, the sensitivity and specificity of the modified ELISA for kala-azar were 97.0% and 98.9%, respectively, for sera from our study population. We hypothesize that individuals with antibody levels greater than the 99th percentile of the negative controls but less than the cutoff point for kala-azar have asymptomatic leishmanial infections.

A ring trial was conducted for molecular identification of Palaearctic species of the subgenus Avaritia, and especially the following four species: Culicoides chiopterus, C. dewulfi, C. obsoletus and C. scoticus. It was based on multiplex polymer­ase chain reaction (PCR) on the molecular markers cytochrome oxidase type 1 (CO1), internal transcribed spacer 2 (ITS-2), and ITS-1. Each of the 13 participating laboratories (from seven dif­ferent countries) received on the 4th of August 2008 a panel of 38 samples of 11 μL of a phosphate-buffered saline (PBS) solu­tion containing parts of a single specimen of insect ground up into 200 μL of PBS, as well as four tubes, identified and men­tioned in the accompanying letter, for which deoxyribonucleic acid (DNA) had already been extracted. The panel was coded with a letter followed by different num­bers. The laboratories had two months from the date of arrival of the samples to give back the results by sending an Excel file containing the coding. The 38 samples used for the trial were exchanged for identification between two international experts (Drs J.C. Delécolle and R. Meiswinkel). Only one identification differed between the two experts: scoticus vs. obsoletus, and sequencing revealed it to be a C. scoticus specimen. Only one laboratory used molecular marker ITS-2, five labo­ratories used ITS-1, and four used CO1. Only two found the expected results. The eight remaining laboratories found some false positive or false negative results. Five out of ten correctly identified the species from the DNA samples. Seven out of ten laboratories had 100% sensitivity

In the framework of Medreonet workpackage on “Regional sur­veillance of vectors”, a Culicoides identification key based on morphology is proposed. This key will help to identify the differ­ent Culicoides species, including those of the Palaearctic region. The tool will be available in a freeware version and in a web version. At time of writing, the key was not yet available but a first draft version was to be presented soon after to Culicoides taxonomists so as to improve it. Currently, females of 85 species including 9 morphological variations are included in a database of 63 descriptors codified in 172 states. These descriptors and states of descriptors were discussed and validated by the par­ticipants of the last taxonomic meeting in Strasbourg, France, in March 2009.

The design of efficient control strategies for Culicoides midges lies in correct species identification. From the approximately 1340 described Culicoides species, only 30 have been incriminated as vectors of bluetongue disease virus. However, the actual number of vector species could be different considering that relatively few species have been studied. In Europe, the most important vec­tor was assumed to be Culicoides imicola, an Afro-Asian vector. However, during the last two years other species such as C. puli­caris (Pulicaris complex), C. dewulfi, C. chiopterus and species of the Obsoletus complex have increased in importance, as their populations have been found abundant in outbreak areas, outside the geographical range of C. imicola. Whereas C. imicola is the most easily identified, C. obsoletus sensu stricto and C. scoticus, from the Obsoletus complex, are extremely difficult to identify by using traditional methods such as morphological examina­tion. The deoxyribonucleic acid (DNA)-barcoding regions is located in the cytochrome oxidase 1 gene (CO1). Recent stud­ies have shown that this region is valuable in the identification of Culicoides species; however, the CO1 fragment to be used must be selected with great care. We propose to standardize the methodology and the selection of the fragment to be amplified to homogenize results obtained by different groups.

To date, the task of identifying Culicoides accurately to the level of species lies largely in the hands of specialists. The develop­ment of an identification key based on morphological criteria would be useful for the standardisation of entomological surveil­lance systems and the training of surveillance agents. The aim was thus to provide a valid and useful morphological key to identify Palaearctic Culicoides species. This key, with numerous illustrations and online access, will be accessible by researchers with different languages and updated by adding new species, new characters, new photographs or new drawings. Two levels of identification will be available: for non-specialists, the key will be based only on microscopic observation of wing pat­terns to identify at least the group of species or some species; for specialists, it will be based on observations and measures of microscopic characters to identify individuals at the species level. For each species an identity card will be added including, when available, information on taxonomy (characters, measure­ments), biology and ecology (breeding site, host preference), distribution (maps), vector status (virus isolation and oral sus­ceptibility), etc. To date, a database with wing photographs of 74 Culicoides species has already been developed, as well as an Excel table with the list of characters. A meeting is planned in Strasbourg the third week of March 2009 between taxonomists to validate and complete characterisation, including morpho­logical variation.

Culicoides species are difficult to identify but, recently, molecu­lar identification tools based on cytochrome oxidase subunit 1 (CO1), internal transcribed spacer 1 or 2 (ITS-1 or ITS-2) have been developed for Palaearctic species including vector spe­cies. In the framework of Medreonet network, the workpackage on “Regional surveillance of vectors” includes guidelines on Palaearctic and Mediterranean Culicoides species identification using molecular tools. Three ring trials were carried out to test whether the methods and tools used in the main laboratories of Europe were adequate and able to identify species correctly. Moreover, a questionnaire was sent to each laboratory to record the protocols and tools used for molecular identification. The four species of the Obsoletus complex, C. obsoletus, C. scoticus, C. chiopterus, and C. dewulfi were selected for the ring trial. All specimens were first morphologically identified by experts. The first ring trial containing eight specimens (four males and four females) of the four species was sent on the 4th of August 2008 to 13 different participating laboratories from seven coun­tries. Two types of material were sent: extracted deoxyribonucleic acid (DNA) (four samples/species) and phosphate-buffered saline (PBS)-ground biting midges (34 samples/species). Eventually, two laboratories did not participate. Only two out of the 11 partici­pating laboratories correctly identified the species. The molecu­lar identification used was based on ITS-1 and ITS-2 markers. A second ring trial was sent in April 2009 with only extracted DNA samples to avoid the different extraction steps which could interfere with tool sensitivity. A total of 20 extracted DNA sam­ples were sent to 10 participating laboratories. Four out of the 10 correctly identified the species. Three laboratories used methods based on ITS-2 or ITS-1 markers, and one laboratory used CO1. Finally, a third ring trial with 20 PBS-ground samples was sent in September 2009 to 10 laboratories. Only one laboratory cor­rectly identified the species. Sensitivity and specificity of the molecular tools used are discussed.