Bluetongue and epizootic hemorrhagic disease in La Réunion; a burden on ruminant farming

Since 2002, the livestock of Réunion Island has been subject to reoccurring outbreaks of Bluetongue (BT) and Epizootic Hemorrhage Disease (EHD). To find out a solution to this problem, that can have severe financial implications to ruminant farmers, a study was carried out between March and September of 2011. The aims of this study were: (1) to confirm the circulation of the viral agents in relation to both host reservoirs and insect vectors; (2) to assess the health status of Réunion Island's livestock; and (3) to identify major risk factors pertaining to ruminant farming due to these viruses. A total of 254 cows from 51 farms and 206 sheep and goats were chosen randomly for testing. Multiple blood samples were taken from all sampled animals. Farming procedures and environmental conditions were assessed for each farm via a questionnaire. Any animal exhibiting clinical symptoms of viral infection was also tested. Serology was done using commercially available LSIVET kits, viral detection was performed via RT-PCR and genotyping was performed externally. Logistic regression was used to assess potential risk factors after a fist of univariate analysis (Chi2). Serology studies suggested that ~50% of ruminants were positive for Bluetongue and ~40% for EHD. EHDV-1 virus was detected in ~5% of animals and bluetongue variant 2 was detected in ~1%. Statistical analysis showed that the major risk factors for Bluetongue and EHD viral infection of ruminant livestock include; the category of the reared livestock, the presence of organic waste, the presence of a water source and the proximity of another farm. Those results are the first step to a better understanding of what could happen in the futur in Western Europe. (Texte intégral

Fièvre catarrhale ovine en Europe en 2014 : épizootie dans les Balkans, progression de la circulation en Italie et en Espagne

L'année 2014 a été caractérisée par une situation épidémiologique nouvelle vis-à-vis de la fièvre catarrhale ovine (FCO) en Europe. Suite à la première notification de foyers de sérotype 4 (BTV-4) en Grèce dans la région du Péloponnèse (mai 2014), onze pays de la région des Balkans ont été touchés par l'épizootie de BTV-4 avec un total de 6 485 foyers déclarés. Fin novembre 2014, en Italie, 25 foyers dus au BTV-4 avaient été confirmés. Une diffusion du virus BTV-1 a de plus été observée dans la partie continentale du pays. En Espagne, les premières suspicions impliquant une souche différente de BTV-4 ont été déclarées en septembre 2014. Aucun lien épidémiologique n'existe cependant avec l'épizootie dans les Balkans. Début décembre, 351 foyers avaient été déclarés en Espagne en dehors de la zone de restriction pour le BTV-4. Par ailleurs, sept foyers de BTV-1 ont été déclarés dans le sud du pays. Au vu des stratégies de lutte appliquées par les pays touchés, il ne fait aucun doute que la vaccination de masse reste le seul moyen réellement efficace de lutte contre la FCO. Les traitements insecticides des animaux permettent au mieux de limiter la transmission et ralentir la diffusion, sans la stopper

Vaccination against two emerging vector-borne diseases: bluetongue and West Nile fever

Since 1998, bluetongue virus has spread in the Mediterranean basin. In 2000, an outbreak of West Nile virus has been reported in horses in the Camargue area in France. In 2003, West Nile was reported in human and horses in the South of France. In the USA, West Nile, which was first reported in New York in 1999, spread all over the country (more than 47 States were infected in 2003). As far as bluetongue is concerned, vaccination with live mono or bivalent vaccines is used in Spain, France and Italy. Concerning West Nile, an inactivated vaccine has been developed but recombinant vaccines will be soon introduced in the American market.La prévention contre les maladies infectieuses à transmission vectorielle repose sur différentes mesures (notamment sanitaires) mais surtout sur la vaccination. En effet, cette stratégie est plus efficace et moins onéreuse que la lutte contre les insectes vecteurs. La dynamique d'évolution et la situation épidémiologique de deux arboviroses (la fièvre catarrhale du mouton et la fièvre du Nil occidental) sont décrites. La prévention vaccinale utilisée ainsi que les types de vaccins utilisés contre ces deux infections sont présentés

News in equine pathology: infectious diseases

Equine diseases and particularly infectious diseases are a major issue for the horse industry because they can have a major economic and/or international impact. The article gives a brief description of the main equine infectious diseases and of their consequences on the horse industry, as well as the current status of research in France.La pathologie, et plus particulièrement le domaine des maladies infectieuses, constitue un sujet d'intérêt majeur pour la filière équine de par l'importance économique et /ou internationale que certaines de ces maladies peuvent engendrer. Après une succincte présentation des principales maladies infectieuses des équidés et de leurs conséquences pour la filière équine, les travaux de recherche menés en France sont présentés

The nonstructural protein NSs of Schmallenberg virus is targeted to the nucleolus and induces nucleolar disorganization

Schmallenberg virus (SBV) was discovered in Germany in late 2011 and then spread rapidly to many European countries. SBV is an orthobunyavirus that causes abortion and congenital abnormalities in ruminants. A virus-encoded nonstructural protein, termed NSs, is a major virulence factor of SBV, and it is known to promote the degradation of Rpb1, a subunit of the RNA polymerase II (Pol II) complex, and therefore hampers global cellular transcription. In this study, we found that NSs is mainly localized in the nucleus of infected cells and specifically appears to target the nucleolus through a nucleolar localization signal (NoLS) localized between residues 33 and 51 of the protein. NSs colocalizes with nucleolar markers such as B23 (nucleophosmin) and fibrillarin. We observed that in SBV-infected cells, B23 undergoes a nucleolus-to-nucleoplasm redistribution, evocative of virus-induced nucleolar disruption. In contrast, the nucleolar pattern of B23 was unchanged upon infection with an SBV recombinant mutant with NSs lacking the NoLS motif (SBVΔNoLS). Interestingly, unlike wild-type SBV, the inhibitory activity of SBVΔNoLS toward RNA Pol II transcription is impaired. Overall, our results suggest that a putative link exists between NSs-induced nucleolar disruption and its inhibitory function on cellular transcription, which consequently precludes the cellular antiviral response and/or induces cell death

Molecular epidemiology of foot and mouth disease virus (FMDV) in Chad

Foot and mouth disease (FMD) is a highly contagious viral disease affecting domestic and wild artiodactyl animals. Its causative agent is foot-and–mouth disease virus (FMDV: Aphtovirus, Picornaviridae). Seven immunologically distinct serotypes (O, A, C, Asia1, SAT 1, SAT 2 and SAT 3) and many subtypes are described worldwide. FMD is one of the most economically devastating diseases of livestock. It is enzootic in many parts of the world including sub-Saharan Africa. Most studies on FMD are carried out in countries where control measures are implemented. On the other hand, in regions such as sub-Saharan Africa, where FMD is endemic and new strains are likely to spread due to animal movements, there are very few published studies on FMDV molecular epidemiology. In Chad particularly, no studies have been conducted to investigate circulating FMDV strains. This work aims to understand the transmission process of FMDV in the pastoral area of Chad, based on a stratified sample of livestock herds (fig. 1). Susceptible animals (cattle, sheep, goats, and camels) were sampled according to the a priori risk of FMD spread in Chad, evaluated by a qualitative risk analysis combining the risks of its introduction and dissemination. In total, 2,195 sera and eight epithelium samples were collected from October to December 2016 in six districts (Batha-Ouest, Batha-Est, Ennedi-Ouest, Wadi-fira, Chari and Lac Wey). Five out of the eight samples tested positive by real-time RT-PCR targeting the FMDV IRES region or the FMDV 3D polymerase coding region. Further analyses targeting specifically the VP1 coding region showed SAT2 type for four samples out of these five FMDV positive samples. Finally amplification and sequencing of the VP1 coding region of these four SAT2 positive samples was carried out to characterize more precisely the strains. Preliminary results were obtained for one sample, confirming the presence of a SAT2 virus, closely related to FMDV SAT2 viruses isolated in Egypt in 2012. Serological analyses are pending. Filling the gap of knowledge concerning the FMDV strains circulating in Chad could both contribute to a better selection of vaccine strains but also to an update of the available molecular epidemiology data of FMD virus in sub-Saharan Africa in general. (Résumé d'auteur

Importance of Borna disease in France both in man and animals

Historically present in Germany for the past two hundred years, Borna disease is a meningoencephalomyelitis which affects mainly horses and sheep. Recent studies have shown evidence of Bornavirus infections in numerous countries, in numerous animal species, and probably also in man. However, the zoonotic nature of the disease is still controversial. BVD RNA has been detected in France both in man and in various animal species (cattle, fox, horse, teal, seagull). Seroprevalence was estimated at around 10% in healthy humans and horses in France. Finally clinical cases of Borna disease have been reported in horses living in France. Therefore, Bornavirus circulates among human and animal populations in France, but it is not yet known whether the virus is emergent or if it has been present for a long time in France.La maladie de Borna, méningo-encéphalomyélite qui affecte principalement les chevaux et moutons, est historiquement présente en Allemagne depuis 200 ans. Des études récentes ont mis en évidence des infections par le Bornavirus dans de nombreux pays et chez de nombreuses espèces animales, incluant probablement l'homme. Le caractère zoonotique de la maladie est toutefois encore controversé. L'ARN du Bornavirus a été détecté en France chez l'homme et chez diverses espèces animales (bovin, renard, cheval, sarcelle d'hiver, goéland). Des taux de séroprévalence ont été estimés à environ 10 % chez l'homme et chez les chevaux sains résidant en France. Enfin, des cas cliniques de maladie de Borna en France ont été rapportés chez des chevaux. Le Bornavirus circule donc dans les populations humaines et animales françaises, mais aucun élément ne permet de savoir s'il s'agit d'un virus émergent sur notre territoire ou s'il est présent depuis longtemps en France

Bluetongue and epizootic haemorrhagic disease viruses in Reunion Island

Objective: Bluetongue (BT) and epizootic haemorrhagic disease (EHD) are arthropod-borne diseases of wild and domestic ruminants caused respectively by viruses belonging to the species Bluetongue virus (BTV) and Epizootic haemorrhagic disease virus (EHDV) within the genus Orbivirus of the Reoviridae. The viruses are transmitted between ruminants by biting midges of the genus Culicoides (Diptera: Ceratopogonidae). BTV went undetected in Reunion Island between its first documented emergence in 1979 and two other serious outbreaks with both BTV-3/ EHDV-6 in 2003, and both BTV-2/EHDV-6 in 2009. In these outbreaks, infected animals developed symptoms including hyperthermia, anorexia, congestion, prostration and nasal discharge. In order to get an overview of the circulation of BT/EHD in Reunion island, an assessment of the prevalence in ruminants native to Reunion Island by a cross-sectional study was undertaken in2011on 67 farms, including a total of 276 cattle, 142 sheep and 71 goats with a total of 489 ruminant samples. Data concerning farm characteristics, type of production, and number of animals were collected through farmer questionnaires for an evaluation of the associated risk factors. In addition, investigation of clinical cases based on the observation of clinical signs was also performed in order to get BTV/EHDV isolates with the aim to track the origins of the circulating strains. Methods: Risk factors analysis Data concerning farm characteristics, type of production, number of animals, closeness to another farm and sugar cane fields, presence of organic and other waste on the farm, exposure to wind, distance to a permanent water point, type of animal housing, presence of ticks on animals, use of treatment against ectoparasites and insects, animal's contacts with other animals or humans, grazing practice, spreading of manure on pastures, presence of Tenrece caudatus, rodent control, number of abortions in the herd in the last 12 months, purchasing behaviour, quarantine of newly purchased animals, other biosecurity factors like hygienic precautions taken by the staff or other people entering the farm (truck driver, vets and other visitors) were taken from a questionnaire which was filled in during an interview with the farmers. This questionnaire was pre-tested on five farms in a preliminary study. The final questionnaire comprised 40 questions of which 75% were closed-ended. Serological assays Specific anti-BTV antibodies were tested in serum samples with a group-specific competitive ELISA based on the VP7 protein using a commercial kit (LSIVetTM Ruminant BT Advanced II- Serum, Life technologies, France). Specific anti-EHDV antibodies were tested using a blocking commercial kit (LSIVetTM Ruminant EHDV-Serum ELISA kit, Life technologies, France). A Sunrise ELISA reader was used for reading at 450 nm (Tecan, France). Optical density values were converted to percentage inhibition (PI). According to the cut-off value of the test, test samples with PI values > 40% for BT and > 60% for EHD were considered as positive. BTV/EHDV genome detection For the BTV group specific real-time RT-PCR, 6 μl of denatured double-stranded RNA prepared with the EZ1 robot and EZ1® Virus Mini Kit v2.0 (Qiagen, France) were reverse transcribed (RT) and amplified using the onestep QuantiTect Probe RT-PCRkit (Qiagen, France) based on segment 1 developed by Toussaint et al. 2007. For the EHDV group specific real-time RT-PCR, 5 μl of denatured double-stranded RNA were reverse transcribed (RT) and amplified using the commercial TaqVetTM EHDV (Life technologies, France).The subgroup-specific EHDV RTPCR based on segment 2 was performed according to Sailleau et al., 2012.Embryonated chicken eggs (ECE) were each inoculated as previously described in Sailleau et al., 2012 Sequence analysis, alignment and phylogenetic analysis To identify the genetic relatedness of the detected virus, phylogenetic analyses were performed with published EHDV sequences. Sixteen full-length VP2 gene sequences were cleaned by hand from the results of several BLAST nucleotide searches as well as direct references from available up-to-date literature and then aligned using the ClustalW translation alignment tool in MEGA (Ver. 5.05). Phylogenetic analysis was performed using the neighbour-joining method using distance measures generated by the p-distance algorithm running 1, 000 iterations with Geneious® Pro. Statistics A Fisher exact test was used to compare differences in prevalence between diseases and species. All statistical procedures were performed using R.3.0.1. A value of P < 0.05 was considered significant. The prevalence rates were estimated as the overall mean and 95% confidence interval (CI). Results: The observed EHD prevalence rate in cattle was 63.77% (95% CI [57.99–69.55]), 5.63% (95% CI [0.03–10.99]) in goats, and 3.70% (95% CI [0.05–6.88]) in sheep, suggesting that EHD occurs more often in cattle than in goats and sheep. These findings were supported by a significant statistical difference in the EHD prevalence rate between species (Fisher exact test, P <<2.2e-16). The observed BT prevalence rate in cattle was 79.62% (95% CI [74.77– 84.47]), 50.70% in goats (95% CI [39.08–62.33]) and 21.48% in sheep (95% CI [14.55–28.40]) with a significant difference in BT prevalence between species (Fisher exact test, P = 4.367e-10). Additionally, three suspected outbreaks occurred during the 2011 study period, one BTV/EHDV negative, one BTV specific and one combined BTV/EHDV outbreak. In total, 14 EHDV positive cases and 1 BTV/EHDV co - infection case were identified. Two further suspected outbreaks were confirmed to involve EHDV and BTV/EHDV. Isolations of EHDV were successful resulting in the identification of the Reunion -specific EHDV-1 serotype. Phylogenetic analyses of segment 2 showed that the Reunion isolate 6010 _2011 belongs to the group C (hypothesised in Anthony et al. 2009 together with EHDV-1 strains from Australia, 1995, Nigeria, 1967, French Guyana, 2011 and New Jersey, USA, 2011). In January 2014, once more suspected outbreaks occurred on cattle with observed clinical signs such as hyperthermia, congestion and nasal discharge. Virus isolations were successful and led us to identify a new EHDV serotype for Reunion island, the EHDV-7 serotype. Conclusion: 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. New circulating EHDV serotype 1 and serotype 7 of unknown origin were isolated in 2011 and 2014 respectively. The mechanisms involved in the introduction, maintenance, and perpetuation of both BTV and EHDV orbiviruses in Reunion Island need to be further investigated. How and when the EHDV serotypes were introduced onto the island are unknown, the most likely being the introduction of infected animals from eastern and southern Africa, Madagascar or Australia over a period of many years. The introduction of Malagasy breeds, which could be considered as orbivirus susceptible breeds many decades ago, is one possible hypothesis. Since 1976, importation of domestic ruminants from these countries has stopped. Until 2008, imports were only from mainland France. The maintenance of both viruses in the livestock population could also be due to the presence of reservoirs such as deer as was the case in many places including southern California between 1990 and 2007 (Roug et al., 2012). Pathogens can easily be shared between wildlife and domestic ruminants which has implications for both the animal production industry and wildlife health. Whether animal reservoirs such as Rusa deer Cervus timorensis rusa imported from Mauritius Island and now present in Reunion Island play a role in EHDV epidemiology need to be investigated. The same species of Rusa deer was introduced on the island of Mauritius in 1639 and serological evidence of both EHDV and BTV circulation is documented. Since 1992, in accordance with European Union regulations, importation of live deer from Mauritius to Reunion Island is forbidden. The intermittent detection of certain serotypes and the occasional appearance of new serotypes suggest that, in the past, regular but separate introductions of BTV/EHDV may have also taken place from Madagascar, and from Southeast Asia including Mauritius via windborne Culicoides. Although it exists, the observed herd immunity in Reunion Island is not high enough to prevent the maintenance of an enzootic cycle, which could also be related to the abundance and activity of Culicoides throughout the year. The findings reported here provide additional hypotheses regarding the ecological characteristics of bluetongue and epizootic haemorrhagic disease and other vector -borne livestock diseases. Sentinel surveillance programmes are a useful way of documenting regionalization zones for diseases, which can be of great importance when securing livestock international markets. (Résumé d'auteur