Abstract
Vesicular stomatitis (VS) is a reportable viral disease which affects horses, cattle, and pigs in the Americas. Outbreaks of vesicular stomatitis virus New Jersey serotype (VSV-NJ) in the United States typically occur on a 5–10-year cycle, usually affecting western and southwestern states. In 2019–2020, an outbreak of VSV Indiana serotype (VSV-IN) extended eastward into the states of Kansas and Missouri for the first time in several decades, leading to 101 confirmed premises in Kansas and 37 confirmed premises in Missouri. In order to investigate which vector species contributed to the outbreak in Kansas, we conducted insect surveillance at two farms that experienced confirmed VSV-positive cases, one each in Riley County and Franklin County. Centers for Disease Control and Prevention miniature light traps were used to collect biting flies on the premises. Two genera of known VSV vectors, Culicoides biting midges and Simulium black flies, were identified to species, pooled by species, sex, reproductive status, and collection site, and tested for the presence of VSV-IN RNA by RT-qPCR. In total, eight positive pools were detected from Culicoides sonorensis (1), Culicoides stellifer (3), Culicoides variipennis (1), and Simulium meridionale (3). The C. sonorensis- and C. variipennis-positive pools were from nulliparous individuals, possibly indicating transovarial or venereal transmission as the source of virus. This is the first report of VSV-IN in field caught C. stellifer and the first report of either serotype in S. meridionale near outbreak premises. These results improve our understanding of the role midges and black flies play in VSV epidemiology in the United States and broadens the scope of vector species for targeted surveillance and control.
Highlights
Vesicular stomatitis virus (VSV; family Rhabdoviridae, genus Vesiculovirus) is the causative agent of vesicular stomatitis (VS) disease in horses, cattle, and pigs in the Americas
maximum likelihood estimate (MLE) could not be calculated for S. meridionale since the few pools tested did not allow the generation of robust estimates. This is the first report with data documenting putative vector species for VSV transmission during an active outbreak in eastern Kansas
While C. sonorensis has been confirmed as a competent vector [11,12], our finding of positive nulliparous C. sonorensis is novel
Summary
Vesicular stomatitis virus (VSV; family Rhabdoviridae, genus Vesiculovirus) is the causative agent of vesicular stomatitis (VS) disease in horses, cattle, and pigs in the Americas. VSV is a reportable disease that results in quarantines and animal movement restrictions on premises with positive animals [1,2] Due to these restrictions and effects of the virus itself, outbreaks of VSV on dairy and beef operations have resulted in significant economic impacts. These include estimated average financial losses of USD 15,565/beef cattle ranch in Colorado [3], approximately USD 50,000 in losses to a single dairy farm in Idaho [4], from USD 200 to USD 250/dairy cow affected with oral lesions in California [5] and Colorado [6], and up to USD 570/dairy cow for those with teat lesions [6]
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