Public veterinary medicine: public health. Serologic evaluation of vesicular stomatitis virus exposure in horses and cattle in 1996.

This research examines the risk factors and exposure levels of the vesicular stomatitis virus (VSV) in livestock in Colorado. It concludes that there was a lower overall VSV seroprevalence in Colorado livestock as compared to epidemic areas.

Objectives and Methods

• The objective of the study was to identify potential risk factors contributing to the spread of vesicular stomatitis (VS), a viral disease affecting livestock, in Colorado’s livestock during 1995 and to assess the level of exposure to the VS virus (VSV) in animals in 1996.
• The researchers conducted a retrospective case-control study and evaluated the seroprevalence (measure of the frequency of individuals in a population who test positive for a specific disease) of VS.
• The study sites comprised 52 premises that had VS-positive animals during the 1995 epidemic and 33 premises that did not, as well as 8 in the vicinity of premises that had VS-positive animals.
• Site visits were conducted in 1996 to gather layout and management data of premises. Additionally, signalment (information detailing an animal’s species, breed, age, and other attributes) and management data were collected from animals from which samples were procured. These samples underwent serological examinations and virus isolation tests.
• The VSV seroprevalence rate for Colorado was estimated using sera acquired for equine infectious anaemia testing and the Market Cattle Identification program in the state.

Results

• Findings indicated at least one animal was seropositive for VSV on 35 out of 52 (67%) premises. Out of 228 animals tested, 71 (31%) were seropositive for VSV.
• Seroprevalence was determined at 37% for horses (63 of 170) and 15% for cattle (8 of 54).
• Seroprevalence of VSV in Colorado’s non-study livestock premises in 1996 was estimated at 1.1% for cattle and 0.8% for horses.

Conclusions

• In summary, the seroprevalence of VSV in Colorado’s livestock was lower than in areas hit by the epidemic. It was also noted that seroprevalence rates in the epidemic hotspots were higher for horses than for cattle.
• There may be an indication in these results that some animals experienced subclinical VSV infection (an infection that’s virtually symptomless) during the epidemic periods, and that livestock might still be exposed to VSV even between the epidemics.