Surveillance along the Rio Grande during the 2020 Vesicular Stomatitis Outbreak Reveals Spatio-Temporal Dynamics of and Viral RNA Detection in Black Flies

Authors: YOUNG, KATHERINE - New Mexico State University; VALDEZ, FEDERICO - New Mexico State University; VAQUERA, CHRISTINA - New Mexico State University; CAMPOS, CARLOS - New Mexico State University; ZHOU, LAWRENCE - New Mexico State University; VESSELS, HELEN - New Mexico State University; MOULTON, KEVIN - University Of Tennessee; Drolet, Barbara; ROZO-LOPEZ, PAULA - Kansas State University; PELZEL-MCCLUSKEY, ANGELA - Animal And Plant Health Inspection Service (APHIS); Peters, Debra; Rodriguez, Luis; HANLEY, KATHRYN - New Mexico State University

Submitted to: Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/2021
Publication Date: 10/1/2021
Citation: Young, K.I., Valdez, F., Vaquera, C., Campos, C., Zhou, L., Vessels, H.K., Moulton, K., Drolet, B.S., Rozo-Lopez, P., Pelzel-Mccluskey, A.M., Peters, D.C., Rodriguez, L.L., Hanley, K.A. 2021. Surveillance along the Rio Grande during the 2020 Vesicular Stomatitis Outbreak Reveals Spatio-Temporal Dynamics of and Viral RNA Detection in Black Flies. Pathogens. https://doi.org/10.3390/pathogens10101264.
DOI: https://doi.org/10.3390/pathogens10101264

Interpretive Summary: Vesicular stomatitis virus (VSV) causes vesicular disease in cattle, pigs and horses that emerges periodically in the US. The virus is transmitted by insects such as black flies but the exact natural cycle of the disease remains unknown. As part of a larger program to decipher the VSV transmission cycle, we conducted a study of black flies along the Rio Grande in southern New Mexico from March to December 2020, while an outbreak of VSV was occurring. We found that black fly abundance differed according to vegetation ground cover and river water flow. Remarkably we detected VSV in 11 insect pools comprising five species of black flies. To our knowledge, this is the first detection of VSV-IN in black flies, and the first detection of VSV in the western US from vectors that were not collected on premises with infected domestic animals. This information is valuable to understanding disease cycle and devise of control strategies.

Technical Abstract: Vesicular stomatitis virus (VSV) emerges periodically from its focus of endemic transmission in southern Mexico to cause epizootics in domestic livestock in the US. The ecology of VSV is complex and involves a potentially diverse, but largely undefined, repertoire of wildlife reservoir hosts and invertebrate vectors. As part of a larger program to decipher the VSV transmission cycle, we conducted a study of the spatiotemporal dynamics of Simulium black flies, a suspected insect vector of VSV, along the Rio Grande in southern New Mexico from March to December 2020. Serendipitously, the index case of VSV-Indiana (VSV-IN) in the US in 2020 occurred in Las Cruces, New Mexico, US, the central point of our study. Black fly abundance differed among three of the 16 transects sampled. Black fly abundance was significantly higher at sites with lower concurrent vegetation biomass (NDVI), lower concurrent flow rate in the Rio Grande, and greater precipitation in the previous two months. We detected VSV-IN in 11 pools comprising five species of black flies using qPCR, 5 of which yielded a VSV-IN sequence. To our knowledge, this is the first detection of VSV-IN in black flies, and the first detection of VSV in the western US from vectors that were not collected on premises with infected domestic animals.