By: Dr. Jocelyn Jansen, OMAFRA; Dr. Maria Spinato, Animal Health Laboratory; Dr. Paula Menzies, Ontario Veterinary College
During the latter half of December 2015 and the start of 2016, the Animal Health Laboratory (AHL) received several submissions of stillborn and aborted lambs with unusual and severe birth defects. Other similar cases were also reported to OVC and OMAFRA veterinarians. The most likely cause of these birth defects is Cache Valley virus (CVV). Blood and tissue samples from fetuses, as well as blood samples from ewes, were tested for the virus and/or antibodies to CVV. On January 14, 2016, test results came back positive for CVV. CVV was previously diagnosed in Ontario flocks in 2011, 2012 and 2013.
CVV is a mosquito-borne virus. It is transmitted to sheep by infected mosquitos that previously fed on infected white tail deer, or that are offspring of infected mosquitos. Late summer and early autumn are the months when the highest amount of virus is present in the mosquito population. CVV is considered endemic in most parts of the United States, Mexico and Canada and infects a wide range of domestic and wild animals, as well as humans. Clinical disease, in the form of birth of deformed lambs is most often reported in sheep. The virus is spread by several species of mosquitos. The Schmallenberg virus that has affected ruminants in many European countries also belongs to the same family of viruses.
Read More Here: Cache Valley Virus