Detection of bovine viral diarrhea virus in stable flies following consumption of blood from persistently infected cattle

Authors: CARLSON, JADEN - UNIVERSITY OF NEBRASKA; VANDER LEY, BRIAN - UNIVERSITY OF NEBRASKA; LEE, SANG - OREGON STATE UNIVERSITY; GROTELUESCHEN, DALE - UNIVERSITY OF NEBRASKA; WALZ, PAUL - AUBURN UNIVERSITY; Workman, Aspen; Heaton, Michael - Mike; BOXLER, DAVID - UNIVERSITY OF NEBRASKA

Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2019
Publication Date: 1/22/2020
Citation: Carlson, J.M., Vander Ley, B.L., Lee, S.I., Grotelueschen, D.M., Walz, P.H., Workman, A.M., Heaton, M.P., Boxler, D.J. 2020. Detection of bovine viral diarrhea virus in stable flies following consumption of blood from persistently infected cattle. Journal of Veterinary Diagnostic Investigation. 32(1):108-111. https://doi.org/10.1177/1040638719898688.
DOI: https://doi.org/10.1177/1040638719898688

Interpretive Summary: Bovine viral diarrhea virus (BVDV) is an important pathogen of cattle that can cause respiratory disease, enteritis and immune dysfunction. BVDV can also cross the placenta and infect the fetus causing abortion or birth of calves persistently infected (PI) with the virus. These PI calves shed virus into the environment throughout their life and serve as the most important source for new infections in cattle. Therefore, it is important to identify these PI calves and remove them from the herd. Currently, resource-intensive individual animal sampling is the only way to identify herds harboring PI-cattle. In this study, we determined the feasibility of using stable flies as a herd-level sampling tool to detect the presence of BVDV in the population. This would allow for surveillance without having to handle each animal. This study found that BVDV is detectable in stable flies fed blood from PI cattle up to three days after the infected blood meal. More research is needed to determine the feasibility of employing this surveillance strategy under field conditions.

Technical Abstract: Control of bovine viral diarrhea virus (BVDV) relies on resource-intensive sampling to detect and remove persistently infected (PI) cattle. Herd-level surveillance tools would be useful for herds with unknown BVDV status and for monitoring herds with BVDV-free status. Our objective was to determine the feasibility of using stable flies as a sampling tool to detect BVDV at the herd level. Stable flies (Stomoxys calcitrans) were fed citrated blood from either BVDV-PI or BVDV-free cattle to establish pools of 100 flies with various proportions of BVDV-fed flies (0%, 1%, 10%, 20%, 40%, or 100% in each pool). BVDV-fed flies in these pools were harvested either 1, 2, or 3 d after consuming BVDV-PI blood to determine the impact of time after feeding. Two replicates of a 3-d by 6-dilution level matrix were produced. BVDV RNA was consistently detected on day 1 when >= 10% of the flies in the pool consumed PI blood. On days 2 and 3, positive BVDV RNA detection was variable and became less consistent. Our results demonstrate that BVDV RNA can be detected in stable flies after feeding on blood from PI cattle. Successful use of stable flies as a surveillance tool will require validation under field conditions.