La Crosse Virus in Aedes japonicus japonicus Mosquitoes in the Appalachian Region, United States

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M. Camille Harris1

, Eric J. Dotseth, Bryan T. Jackson, Steven D. Zink, Paul E. Marek, Laura D. Kramer, Sally L. Paulson, and Dana M. Hawley

Author affiliations: Virginia Polytechnic Institute and State University , Blacksburg, Virginia, USA (M.C. Harris, B.T. Jackson, P.E. Marek, S.L. Paulson, D.M. Hawley); West Virginia Department of Health and Human Resources, Charleston, West Virginia, USA (E.J. Dotseth); New York State Department of Health, Slingerlands, New York, USA (S.D. Zink, L.D. Kramer)

Abstract

La Crosse virus (LACV), a leading cause of arboviral encephalitis in children in the United States, is emerging in Appalachia. For local arboviral surveillance, mosquitoes were tested. LACV RNA was detected and isolated from Aedes japonicus mosquitoes. These invasive mosquitoes may significantly affect LACV range expansion and dynamics.

La Crosse virus (LACV; family Bunyaviridae, genus Orthobunyavirus), in the California serogroup, is the major cause of arboviral encephalitis among children in the United States (1). Since its 1963 discovery in Wisconsin, LACV has been identified in 30 other US states (2). These include states within the Appalachian Mountain region (West Virginia, Virginia, Ohio, Tennessee, and North Carolina), which is an emerging focus of LACV (3).

The primary vectors of LACV, Aedes triseriatus mosquitoes, are present in southwestern Virginia and West Virginia, but 2 invasive congeners—Ae. albopictus and Ae. japonicus—have recently emerged (3). Both species have been shown to be competent experimental LACV vectors (4,5). Although LACV has been isolated from Ae. albopictus mosquitoes (6), previously it had only been detected in the Asian bush mosquito (Ae. japonicus japonicus) in Tennessee (7). Ae. japonicus mosquitoes are mammalophilic container breeders that co-occur with the primary LACV vector (Ae. triseriatus mosquitoes). Known to feed on humans (8), Ae. japonicus mosquitoes are found in woodlands (where this “rural encephalitis” virus is endemic) and urban areas (9).

Thumbnail of Locations of detection of La Crosse virus (LACV) RNA and virus isolation from Aedes japonicus mosquito pools. The red stars represent counties of the Ae. japonicus LACV isolates, and the blue stars represent counties of Ae. japonicus LACV RNA detection.

Figure 1. Locations of detection of La Crosse virus (LACV) RNA and virus isolation from Aedes japonicus mosquito pools. The red stars represent counties of the Ae. japonicus LACV isolates, and the blue...

To ascertain the public health risk that Ae. japonicus mosquito vectors represent for LACV transmission, we examined mosquitoes from West Virginia and Virginia for presence of this arbovirus. We report 2 independent isolations of LACV from adult Ae. japonicus mosquitoes in southwestern Virginia and 7 field detections of LACV RNA from adults (Virginia and West Virginia) and adults reared from eggs (Virginia). Our findings suggest a potential role of this invasive vector in the ecology of LACV in Appalachia (Figure 1).

Dr. Harris is a wildlife veterinarian and disease ecologist. Her primary research interest is understanding how anthropogenic environmental changes affect disease dynamics, especially zoonotic and vectorborne diseases.

Acknowledgments

We thank Amy Lambert for conducting RT-PCR and sequencing of the 2009 isolate from Montgomery County, Virginia; Dee Petit and Andrew Luna for technical assistance; and Nate Lambert, Allen Patton, Bonnie Fairbanks, Jennifer Miller, and Laila Kirkpatrick for field and laboratory assistance. In West Virginia, Christi Clark, Chris Boner, and Lindsay Kuncher provided laboratory assistance, and field surveillance was conducted by Kristin Alexander, Stephen Catlett, Hannah Cavender, Robert Deneer, Jennifer Beamer Hutson, Mickey King-Fowler, Dustin Mills, Daniel Payne, and Courtney Stamm. We thank the Wadsworth Center sequencing core for sequencing 1 isolate.

Mosquito surveillance in West Virginia was supported in part by a CDC Epidemiology and Laboratory Capacity for Infectious Diseases grant. Contributions of M.C.H. were supported in part by a National Institutes of Health Ruth L. Kirschstein National Research Service Award for Individual Predoctoral Fellows (no. 1F31AI080160-01A1).

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Figures

Table

Table. Detection of LACV RNA and virus isolations in Aedes japonicus mosquito pools from Virginia and West Virginia, USA

Suggested citation for this article: Harris MC, Dotseth EJ, Jackson BT, Zink SD, Marek PE, Kramer LD, et al. La Crosse virus in Aedes japonicus japonicusmosquitoes in the Appalachian Region, United States. Emerg Infect Dis. 2015 Apr [date cited]. http://dx.doi.org/10.3201/eid2104.140734

DOI: 10.3201/eid2104.140734

1Current affiliation: United States Geological Survey, Reston, Virginia, USA.