Ecology of Hantaan Virus at Twin Bridges Training Area, Gyeonggi Province, Republic of Korea, 2005–2007

Abstract

The Twin Bridges Training Area (TBTA) in the Republic of Korea consists of dirt roads, barren training areas, and forested hillsides adjacent to linear and broad expanses of tall grasses, herbaceous, and scrub vegetation. Of the six species of small mammals, the striped field mouse, Apodemus agrarius, was the most frequently captured (96.1%). Apodemus agrarius capture rates varied from 17.7 to 33.2% during three trapping periods. Gravid females were observed during

Ecological surveillance of small mammals at Dagmar North Training Area, Gyeonggi Province, Republic of Korea, 2001-2005

“…Apodemus agrarius is the most frequently collected rodent in rural areas and inhabits a broad range of habitats, including unmanaged tall grass habitats of military lands that provide plentiful food and ground cover conducive to high population densities of (Youngman 1956, Jones and Barber 1957, Davis 1957, Tyson 1967). Similar to surveys at other military training sites, A. agrarius accounted for >90% of the small mammals (O'Guinn et al 2008, Sames et al 2009). These relatively large populations increase the risk of hantaviruses, especially as aerosolization of virus laden dusts are produced during convoys, military maneuvers, and firing (back‐blast) artillery.…”

“…Off‐road trails and ruts may provide favorable environmental conditions during periods of non‐use, but these same activities result in increased disruption, predation, dispersion, and competition (conflict and wounding) and transmission of pathogens. In addition, while invasive herbaceous vegetation (e.g., giant ragweed) may provide extensive ground cover during the growing season, it provides limited ground cover and protection while foraging against aerial predators during the winter and spring seasons (O'Guinn et al 2008, Sames et al 2009). Agricultural activities (e.g., cut grasses along earthen banks separating rice paddies), provided limited ground cover, which resulted in very low capture rates of A. agrarius .…”

“…Another result of the loss of winter ground cover is the presumed increase in mortality rates for displaced animals, which may result in the dispersion of ectoparasites (e.g., fleas and ticks) that seek alternate hosts when natural host populations are unavailable. These associated disturbances and environmental modifications, especially during periods of high reproductive capacity in the fall, increase the potential for dispersal of associated ectoparasites and disease causing pathogens (e.g., murine typhus, ehrlichiosis, anaplasmosis, Lyme disease, spotted fever group Rickettsia , and tick‐borne encephalitis) (Youngman 1956, Davis 1957, Tyson 1967, Hong and Lee 1984, Mills et al 1998, Lee et al 1992, 2002, Douglas et al 2001, Mackelprang et al 2001, Hinson et al 2004, O'Guinn et al 2008, Kim et al 2008, 2009, Chae et al 2008a, Sames et al 2009, Kim et al 2010a).…”

“…Zoonotic diseases harbored by small mammals (Yager 1954, Lee et al 1986, Corwin et al 1990, Pon et al 1990, Marshall and Rhodes 1996, Sames et al 2009, Song et al 2009a, O'Guinn et al 2010) and associated ectoparasites (Pruitt 1954, Cowdrey 1987, Chae et al 2003, 2008a, Kim et al 2005, 2006, 2010a, O'Guinn et al 2008, Payne et al 2010) pose serious public health threats to U.S. and Korean military populations while training in field environments in the Republic of Korea (ROK). Unmanaged and disturbed military lands, e.g., Dagmar North Training Area (DNTA), are characterized by relatively large small mammal populations where there is an abundance of tall grasses and invasive crawling (kudzu) and other herbaceous and scrub vegetation (O'Guinn et al 2008, Sames et al 2009). These training sites are host to a variety of military activities (e.g., establishment of cantonment and command and control centers and firing positions, personnel and wheeled and tracked vehicle maneuvers, air assault and helicopter resupply operations, and other routine activities) which expose soldiers to small mammals and their associated ectoparasites and the pathogens they harbor.…”

“…The consequences of these activities and other environmental factors (e.g., occasional flooding of low‐lying areas) result in the increased competition for food and harborage and displacement and dispersal of small mammals (Hong and Lee 1984). Furthermore, these activities and host interactions increase the potential for hantavirus infections through dispersal and competition (Lee et al 1978, Hinson et al 2004, Baek et al 2006, Sames et al 2009, Song et al 2009b), dispersal of intestinal parasites (Chai et al 2007), and dispersal of associated ectoparasites (Hong et al 1975, Lee et al 1983, Kim et al 2010b, 2010c) and zoonotic pathogens, e.g., leptospriosisis (Rim et al 1993, Cho et al 1999, O'Guinn et al 2010, Payne et al 2010), Orientia tsutsugamushi (Jackson et al 1957, Ley and Markelz 1961, Ree et al 1991, 1995, Song et al 1998, O'Guinn et al 2010, Payne et al 2010), Rickettsia, Ehrlichia, Anaplasma , and Bartonella spp. (Chae et al 2003, 2008a, Kim et al 2005, 2006, O'Guinn et al 2010, Payne et al 2010), Borrelia burgdorferi (Park et al 1992, 1993, Kee et al 1994) and viruses in the mammalian tick‐borne flavivirus group (Kim et al 2008, 2009, Ko et al 2010).…”