Cache Valley virus infection in Texas sheep flocks.

Cache Valley virus (CVV), an arbovirus indigenous to the United States, has been implicated as an important teratogenic agent in sheep. The prevalence and distribution of Texas sheep with CVV-specific antibody were investigated. In 1981, 19.1% of 366 sheep located in 22 counties of Texas had antibodies specific for CVV. Of 50 flocks examined in the major sheep-producing counties in Texas, 34 had sheep with antibodies that reacted with CVV, including all sheep tested in 6 flocks that were seropositive. Sera obtained from sheep at the Texas Agricultural Experiment Station at San Angelo between 1986 and 1989 were also examined for CVV-specific antibody because this flock was the subject of the episode of CVV-associated congenital malformations during the 1986 and 1987 lambing season. Approximately 8.6% of 104 sheep in 1986, 63.4% of 164 in 1987, 11.3% of 44 in 1988, and 71.9% of 89 in 1989 from the Texas Agricultural Experiment Station at San Angelo tested were seropositive. The data indicate that CVV infections in sheep were widespread in Texas in 1981 and that the virus is enzootic in sheep at the Texas Agricultural Experiment Station in San Angelo, where the episode of congenital malformations had initially been reported in 1987.