Abortion of a sheep fetus due to Cache Valley Fever Virus
By Judy Akins, DVM, MS
A term sheep fetus was submitted to the Texas A&M Veterinary Diagnostic Laboratory (TVMDL) for a routine necropsy. The fetus had scoliosis. The skull and maxillae were deviated to the left. There was no intact brain tissue in the cranial vault. In place of the brain there was a thin membranous sac filled with reddish colored fluid. There were no significant lesions in any of the organs in the thoracic or abdominal cavities. Because of the type of lesions identified at the gross necropsy, a PCR test for Cache Valley Fever was performed with a positive result.
The Cache Valley virus is in the order Bunyaviridae and genus Orthobunyavirus. It was first isolated from mosquitoes collected in Utah’s Cache Valley. This virus can cause outbreaks of spontaneous abortion and congenital malformations in sheep. In a non-pregnant adult animal, an infection may result in a slight febrile response with minimal or no clinical signs. In a pregnant animal, especially one that does not have antibodies from a previous exposure, an infection can result in severe congenital abnormalities depending upon the stage of gestation. The virus appears to have a tropism for the central nervous system and musculoskeletal system. There is currently no vaccine or known treatment for Cache Valley virus. Rare cases of aseptic meningitis attributed to Cache Valley Fever have been reported in humans.
To learn more about this case, contact Dr. Judy Akins, clinical and anatomic pathologist. For more information about TVMDL’s test offerings, call 1.888.646.5623 or visit tvmdl.tamu.edu.