Epizootic Hemorrhagic Disease Virus Type 6: Disease, RNAemia and Abortions - The Israeli Experience

Epizootic Hemorrhagic Disease (EHD) is non-contagious viral disease affecting mostly white-tailed deer and cattle. It can cause fever, hemorrhages, excessive salivation, agalactia, loss of body weight, abortion and occasionally death. A large outbreak of epizootic hemorrhagic disease virus serotype 6 (EHDV-6) was identified in several Israeli cattle farms towards the end of 2015. In this study, we examined the persistence of EHD-6 viral RNA circulation in whole blood (RNAmia) from six naturally infected sentinel calves. RNAmia duration was estimated based on real-time re-verse transcription polymerase chain reaction (RT-qPCR) of whole blood samples. Our results indicate that EHDV RNAmia lasted for approximately four months from the presumed date of the initial natural infection. Additionally, based on the data of PCR-positive field samples from sick animals and aborted cattle fetuses, along with isolated viruses from samples taken at the same period of time as a rou- tine diagnostic procedure, we conclude that the outbreak took place between late September and November 2015. Analysis of abortion cases throughout this period (all aborted fetuses and placentas tested for abortogenic pathogens), suggests that EHDV-6 was involved in the part of abortion cases in this cattle population. To our knowledge this is the first study of field monitoring of EHDV RNAmia, and first EHDV RNA detection in aborted fetuses. spp . was performed by inoculation of abomasal contents into Fry’s mycoplasma broth (Fre -undt, 1983) and platedonto mycoplasma agar. Placental, lung and abomasal smears were stained by Stamp’s modified Zeihl Neelsen method and with an FITC monoclonal antibody for Chlamydia spp. (Cellabs, Australia). Abomasal contents were inoculated into tetra-thionate broth for Salmonella enrichment which was streaked onto MacConkey and Brilliant Green agar after 24 hours incubation. All cultures excluding Salmonella were incubated in a 5% carbon dioxide atmosphere.