Location: Arthropod-borne Animal Diseases Research
2019 Annual Report
Objectives
1. Ascertain the viral ecology of disease and factors mediating the emergence of VSV.
1.A. Characterize epidemiological, biotic and abiotic factors associated with the emergence and transmission of VSV in endemic versus non-endemic settings.
2. Develop intervention strategies to minimize the impact of VSV disease outbreaks.
2.A. Develop means to detect and characterize emergent VSV strains and use these data to generate models that predict future outbreaks.
2.B. Identify vector transmission control strategies based on our understanding of vector-host interactions.
Approach
1. A comprehensive analysis of Vesicular Stomatitis (VS) outbreaks occurring in the U.S. from 2004-2016 will be conducted to determine the relationship between the geographical location of premises reporting VS outbreaks and the spatial and temporal variability in a large suit of ecological variables. Multiple data streams involving disease occurrence and ecological conditions will be obtained from multiple sources and harmonized for integration and analysis. These data sources include; a) outbreak occurrence data inclusive of geo-location, host species, number of animals affected and onset date, b) ecological data analysis c) biotic and abiotic variables inclusive of animal density, hydrological features and streams, elevation and surface water properties, air temperature and precipitation, vegetation ENSO (El Nino Southern Oscilation) data, soil properties and long term trends in environmental variables. Additional data such as water quality monitoring and U.S. census data for human population distribution may be included. These data will be harmonized and univariate and multivariate statistical analysis will be conducted to determine the best set of explanatory variables for temporal and spatial patterns. These analyses will be used to identify ecological variables associated with VS disease occupancy and spread in the western U.S. and to develop predictive models for disease spread.
2. The characterization of VSV transmission in endemic vs non-endemic settings will be conducted in collaboration with Mexico’s SENASICA-EADC laboratory to conduct genomic sequencing and phylogeographic characterization of viral strains collected through VS surveillance activities in Mexico and to identify the ecological and environmental factors associated with the occurrence of VSV in Mexico. A collaboration with USDA-APHIS will established to determine the phylogeopraphic characteristics of VSV strains causing outbreaks in the U.S. This information will be used to create predictive models for VSV occurrence in Northern Mexico and the U.S.
3. To identify intervention strategies agains VSV outbreaks, we will first assess the success of specific lineages to spread over a large geographic range and determine the factors of viral virulence not found in strains remaining within endemic foci. This analysis will be conducted through comparison of the pathogeneis of lineage, identification of phyenotypic differences among strains and mutation of infectious genetic clone derived from virulent strain lineage observed in swine. The endemic and epidemic lineages will be compared to determine transmissibility by insect vectors.
Progress Report
Insect collections in likely Vesicular Stomatitis Virus (VSV) hotspots started in April and will proceed until September. This is monthly sampling for likely VSV disease vector species such as biting midges, black flies, and sand flies. Mosquito magnet traps are used for surveillance on four equine and four bovine farms. There are two consecutive days of 24 hour sampling to get an idea of the insect populations. April and May sampling were very low because of very wet, cool weather conditions.
Due to an ongoing VSV-Indiana outbreak, additional traps are being set at infected premises.
A baseline VSV-Culicoides midge time-course infection has been completed with a known archived isolate. These results will be used to compare results with recombinant VSV lineage isolates constructed by Foreign Animal Disease Research Unit (FADRU), ARS-Plum Island, NY.
Additional studies to inform the ecological epidemiology of Culicoides are ongoing, such as non-conventional transmission mechanisms (venereal), preferences and physiological costs of blood meal temperature, and the effect of multiple blood meals on virus titers.
For additional progress reports, please refer to project 8064-32000-059-00D
Accomplishments
