Vesicular stomatitis (VS) is an economically devastating disease of livestock, wildlife, and humans in the Americas. Despite strong circumstantial evidence for the role of arthropods in epizootics, no hematophagous vector has been found. Based on the spatiotemporal association of grasshopper outbreaks and VS epizootics, we investigated the potential role of these insects as vectors and reservoirs of the disease. Here we show the critical steps in the grasshopper-bovine transmission cycle, including: 1) 62% of grasshoppers (Melanoplus sanguinipes) fed vesicular stomatitis virus (VSV) from cell culture became infected, with titers reaching 40,000-times the inoculative dose, 2) 36% of grasshoppers cannibalizing VSV-infected grasshopper cadavers became infected, amplifying virus by 400-fold, 3) 1 of 3 cattle consuming VSV-laden grasshopper cadavers contracted typical VS and shed virus in saliva, and 4) 15% of grasshoppers became infected when fed saliva from this infected cow. The ecological conditions and biological processes necessary for these transmissions to occur are present throughout much of the Americas.
Species 1: Orthoptera Acrididae Melanoplus sanguinipes (lesser migratory grasshopper)
Keywords: epizootiology, disease
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