TY - JOUR
T1 - Movement of st. Louis encephalitis virus in the western united states, 2014-2018
AU - Swetnam, Daniele M.
AU - Stuart, Jackson B.
AU - Young, Katherine
AU - Maharaj, Payal D.
AU - Fang, Ying
AU - Garcia, Sandra
AU - Barker, Christopher M.
AU - Smith, Kirk
AU - Godsey, Marvin S.
AU - Savage, Harry M.
AU - Barton, Vonnita
AU - Bolling, Bethany G.
AU - Duggal, Nisha
AU - Brault, Aaron C.
AU - Coffey, Lark L.
N1 - Funding Information:
We acknowledge funding support from the Pacific Southwest Regional Center of Excellence for Vector-Borne Diseases funded by the US Centers for Disease Control and Prevention (Cooperative Agreement 1U01CK000516). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. This work was made possible by the contributions of SLEV-positive mosquito pools from Kirk Smith (AZ) at Maricopa County Environmental Services Department, Vivek Raman at the Southern Nevada Health District, Andree Hunkapiller, Noah Lawler and Donna Mulrooney from the Oregon Veterinary Diagnostic Laboratory (OVDL), Vonnita Barton at Idaho Bureau of Laboratories, and Bethany Bolling (TX) at Texas Department of State Health Services. We also acknowledge the following mosquito abatement agencies who contributed SLEV-positive mosquito pools from California that were included in this study: Coachella Valley Mosquito and Vector Control District, Kern Mosquito and Vector Control District, Butte County Mosquito and Vector Control District, Delano Mosquito Abatement District, Fresno Mosquito and Vector Control District, Imperial County Vector Control Program that is part of the Imperial County Public Health Department, Madera County Mosquito and Vector Control District, Merced County Mosquito Abatement District, Sutter-Yuba Mosquito and Vector Control District, and Tulare Mosquito Abatement District. Sandra Garcia (UC Davis) provided technical assistance with initial mosquito pool testing as part of the California surveillance program, and Janae Stovall and Karen Boroughs (CDC) provided sequencing technical assistance. Sequences were also provided by Steve Aspen, Payal D. Maharaj, Harry Savage and Aaron Brault at the CDC and Nisha Duggal at the Virginia Polytechnic Institute and State Uni-versity. We acknowledge Ana Ramirez for editing the manuscript.
Publisher Copyright:
© 2020, Public Library of Science. All rights reserved.
PY - 2020/6
Y1 - 2020/6
N2 - St. Louis encephalitis virus (SLEV) is a flavivirus that circulates in an enzootic cycle between birds and mosquitoes and can also infect humans to cause febrile disease and sometimes encephalitis. Although SLEV is endemic to the United States, no activity was detected in California during the years 2004 through 2014, despite continuous surveillance in mosquitoes and sentinel chickens. In 2015, SLEV-positive mosquito pools were detected in Maricopa County, Arizona, concurrent with an outbreak of human SLEV disease. SLEV-positive mosquito pools were also detected in southeastern California and Nevada in summer 2015. From 2016 to 2018, SLEV was detected in mosquito pools throughout southern and central California, Ore-gon, Idaho, and Texas. To understand genetic relatedness and geographic dispersal of SLEV in the western United States since 2015, we sequenced four historical genomes (3 from California and 1 from Louisiana) and 26 contemporary SLEV genomes from mosquito pools from locations across the western US. Bayesian phylogeographic approaches were then applied to map the recent spread of SLEV. Three routes of SLEV dispersal in the western United States were identified: Arizona to southern California, Arizona to Central California, and Arizona to all locations east of the Sierra Nevada mountains. Given the topography of the Western United States, these routes may have been limited by mountain ranges that influence the movement of avian reservoirs and mosquito vectors, which probably represents the primary mechanism of SLEV dispersal. Our analysis detected repeated SLEV introductions from Arizona into southern California and limited evidence of year-to-year persistence of genomes of the same ances-try. By contrast, genetic tracing suggests that all SLEV activity since 2015 in central California is the result of a single persistent SLEV introduction. The identification of natural barriers that influence SLEV dispersal enhances our understanding of arbovirus ecology in the western United States and may also support regional public health agencies in implementing more tar-geted vector mitigation efforts to protect their communities more effectively.
AB - St. Louis encephalitis virus (SLEV) is a flavivirus that circulates in an enzootic cycle between birds and mosquitoes and can also infect humans to cause febrile disease and sometimes encephalitis. Although SLEV is endemic to the United States, no activity was detected in California during the years 2004 through 2014, despite continuous surveillance in mosquitoes and sentinel chickens. In 2015, SLEV-positive mosquito pools were detected in Maricopa County, Arizona, concurrent with an outbreak of human SLEV disease. SLEV-positive mosquito pools were also detected in southeastern California and Nevada in summer 2015. From 2016 to 2018, SLEV was detected in mosquito pools throughout southern and central California, Ore-gon, Idaho, and Texas. To understand genetic relatedness and geographic dispersal of SLEV in the western United States since 2015, we sequenced four historical genomes (3 from California and 1 from Louisiana) and 26 contemporary SLEV genomes from mosquito pools from locations across the western US. Bayesian phylogeographic approaches were then applied to map the recent spread of SLEV. Three routes of SLEV dispersal in the western United States were identified: Arizona to southern California, Arizona to Central California, and Arizona to all locations east of the Sierra Nevada mountains. Given the topography of the Western United States, these routes may have been limited by mountain ranges that influence the movement of avian reservoirs and mosquito vectors, which probably represents the primary mechanism of SLEV dispersal. Our analysis detected repeated SLEV introductions from Arizona into southern California and limited evidence of year-to-year persistence of genomes of the same ances-try. By contrast, genetic tracing suggests that all SLEV activity since 2015 in central California is the result of a single persistent SLEV introduction. The identification of natural barriers that influence SLEV dispersal enhances our understanding of arbovirus ecology in the western United States and may also support regional public health agencies in implementing more tar-geted vector mitigation efforts to protect their communities more effectively.
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U2 - 10.1371/journal.pntd.0008343
DO - 10.1371/journal.pntd.0008343
M3 - Article
C2 - 32520944
AN - SCOPUS:85087362515
SN - 1935-2727
VL - 14
SP - 1
EP - 22
JO - PLoS neglected tropical diseases
JF - PLoS neglected tropical diseases
IS - 6
M1 - e0008343
ER -