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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 <

Rift valley fever (RVF) is a zoonotic disease which circulates in many African countries as well as in the Arabian Peninsula. Epizootics are characterized by large sweeping abortion storms and significant mortality in adult livestock (primarily sheep, goats, and cattle), with newborn animal mortality approaching 100%. In most human cases, the disease is characterized by a self-limiting febrile illness progressing to more serious complications in only 1 to 2% of infected individuals (hepatitis, encephalitis, blindness or hemorrhagic syndrome. Further to the confirmation of a first human case of RVF in 2007 in Comoros, isolation of the virus was successfully achieved on suspected human cases. These viruses are genetically closely linked to the 2006-2007 Kenyan isolates. Serological surveys for antibodies to Rift Valley fever (RVF) virus were carried out in ruminants on Mayotte following the confirmation of a first human case of RVF in Comoros in 2007. The results suggested low level circulation of RVF virus on Mayotte as early as 2004, with neither human nor animal population experiencing outbreaks of the disease.