Bluetongue is a viral disease that affects domestic and wild ruminants, including sheep, cattle, goats, and deer. The disease is caused by the bluetongue virus (BTV), which is spread primarily by biting
Culicoides midges (often called “no-see-ums") and potentially other biting insects. Because transmission depends on these insects, bluetongue typically occurs seasonally and is most common in warmer climates where midge populations are active. The disease is not contagious between animals through direct contact, but may be spread by contaminated objects (e.g., surgical equipment, needles) and from dam to fetus during pregnancy. Bluetongue is not a human health risk.
Multiple BTV serotypes circulate in the United States. As of 2022, several serotypes are considered established in the United States, including serotypes 3, 6, 10, 11, 12, 13, and 17. Other serotypes (1, 2, 5, 9, 14, 15, 18, 19, 22, and 24) have been reported but are not consistently detected. Some serotypes have never been reported in the United States. In particular, BTV serotype 8 has never been reported here and remains a concern due to its disease severity and potential ability to cross the placenta in cattle.
Clinical signs can vary widely depending on the animal species infected and the specific strain of the virus; the disease can be fatal. Sheep are typically the most severely affected and may develop fever, lameness, swelling around the mouth and face, difficulty breathing, and in severe cases a characteristic blue appearance of the tongue. Cattle often show few or no signs of illness, although they can carry the virus and contribute to its spread. Sheep and cattle infected during pregnancy may abort or deliver malformed or “dummy" lambs or calves. Outbreaks can lead to significant economic impacts due to reduced productivity, animal losses, and trade restrictions. Managing bluetongue focuses on reducing exposure to biting midges and monitoring herd health.
Bluetongue Cases in Oregon
If you suspect a case of Bluetongue, report it immediately:
Contact your local veterinarian
For veterinarians:
Oregon State Veterinarian
Phone: 503-986-4711
For wild animals:
Oregon Department of Fish and Wildlife
Phone: 1-866-968-2600
Resources
ODA Resources
Other Resources