Serological Surveillance of Scrub Typhus, Murine Typhus, and Leptospirosis in Small Mammals Captured at Twin Bridges Training Area, Gyeonggi Province, Republic of Korea, 2005–2007

Soldiers from the Republic of Korea and the United States conduct armistice military operations at Twin Bridges Training Area (TBTA) located near the demilitarized zone (DMZ) and are exposed to zoonotic disease pathogens that small mammals and their potentially disease-carrying ectoparasites transmit. TBTA is a 36 km2 rural training site with small villages and various forms of agriculture along its boundary. At TBTA, rodents, insectivores, and their ectoparasites are commonly found in association with unmanaged habitats of various densities of tall grasses, herbaceous plants, shrubs, briars, and crawling vegetation. Rodents and insectivores were collected during the winter (November-December 2005 and December 2006) and early spring (March 2007), and serologically tested for the presence of scrub typhus, murine typhus, and leptospirosis antibodies. Of the six species of small mammals collected, Apodemus agrarius, the common striped field mouse and known reservoir of scrub typhus, was the most frequently collected (96.1%), followed by Crocidura lasiura (2.5%), Micromys minutus (0.5%), Myodes regulus (0.5%), Mus musculus (0.3%), and Rattus rattus (0.1%). A. agrarius (56.1%), M. musculus (66.7%), M. minutus (25%), and R. rattus (100%) were positive for scrub typhus antibodies. Only A. agrarius (14.7%) and C. lasiura (4.5%) were positive for murine typhus antibodies, whereas only A. agrarius (1.5%) was seropositive for leptospirosis. Seroprevalence rates of scrub typhus and murine typhus based on weight and sex of A. agrarius are presented.