Cache Valley virus (CVV) has been found in sheep and deer in Arkansas, according to a new report.
The investigation, which took a One Health approach, found CVV resulted in adverse reproductive outcomes in the animals and also noted human cases may be underdiagnosed (Emerg Infect Dis 2025;31[6]:1231-1234).
CVV—an arbovirus in the Bunyaviridae family—is primarily associated with livestock, causing reproductive issues like congenital defects in sheep and potentially posing a risk to human health, especially pregnant individuals.
“This report highlights CVV as an underreported arboviral infection affecting small ruminants, and possibly other animals, in Arkansas,” said report author Laura K. Rothfeldt, DVM, DACVPM, the State Public Health Veterinarian with the Arkansas Department of Health.
Looking for CVV
The investigation was conducted in response to the detection of CVV RNA in tissue from an aborted lamb at a farm (Farm A) in central Arkansas from February 2023. The farmer reported an abortion storm which had an attack rate of approximately 30%. During 2020, a single case of CVV was reported in a seropositive sheep from a flock at another farm (Farm B), located in northwest Arkansas.
Testing of 39 ewes at Farm B revealed 21% were seropositive for CVV at breeding, and 79% were seronegative. Among the seronegative ewes, 10% seroconverted during pregnancy. Among 13 deer tested in three counties, 85% were seropositive for CVV. While 204 mosquito pools were tested, none were positive for CVV.
No Human Cases
No cases in humans were identified; however, testing data are limited. “Although no human infections were identified during this investigation, it is possible that these infections are going unrecognized given the limited arboviral testing patterns that were revealed,” Dr. Rothfeldt said.
More targeted testing could help us understand how many human cases of CVV are out there. “Future research should include enhanced case surveillance in humans, focusing on persons with meningitis and/or encephalitis of unknown etiology, especially during peak mosquito season, to identify true cases of CVV in people,” Dr. Rothfeldt said. “More thorough and sustained vector surveillance should be prioritized to identify reservoirs and high-risk locations throughout the state for targeting control efforts to prevent both human and animal infections.”
Dr. Rothfeldt reported no relevant financial disclosures.
