BORRELIA-BURGDORFERI IN EASTERN VIRGINIA - COMPARISON BETWEEN A COASTAL AND INLAND LOCALITY

In Virginia, Borrelia burgdorferi was more prevalent in a site along t he Atlantic Ocean, near Maryland, than in an inland site near Williams burg and Yorktown. At the coastal site on Assateague Island, B. burgdo rferi was isolated from 4.2% of 475 animals sampled, including four sp ecies of small mammals. Serologic tests indicated that 25-37% of the s mall rodents assayed had been exposed to B. burgdorferi. Immunofluores cence antibody assays specific for B. burgdorferi showed spirochete in fection in Ixodes scapularis and Dermacentor variabilis but not in oth er species of ticks also examined from this site. At another coastal s ite (Parramore Island), no evidence of Peromyscus leucopus was found, no immature specimens of I. scapularis were collected, and no isolatio ns were made from numerous raccoons or small mammals sampled. Borrelia burgdoferi infection was found in one I. cookei nymph, but not in num erous specimens of I. scapularis or other tick species from this local ity. At the inland site between Williamsburg and Yorktown, B. burgdofe ri was isolated from two small mammal species and antibodies to B. bur gdorferi were found in only 7-10% of the small mammals sampled. Ixodes scapularis were less abundant at this locality than at the Assateague Island site. Borrelia burgdoferi spirochetes were found in I. scapcul aris and a single nymph of Amblyomma americanum, but not in any of num erous specimens of four other species. Infection with B. burgdorferi w as found in 20% of unfed adult I. scapularis from vegetation, but in o nly 0.2% of numerous adults from hunter-killed deer. Infection in imma ture ticks was much lower than at Assateague Island. Borrelia burgdorf eri may be more prevalent along the Atlantic coast than in inland area s. Isolations, seroprevalence, immature I. scapularis densities, and s pirochete infection rates in ticks were higher at the Assateague Islan d site than the Williamsburg/Yorktown site. Consequently, the risk of human exposure to Lyme disease may be higher in some parts of the coas tal area than elsewhere in Virginia. Overall, B. burgdorferi is less i ntense in Virginia than in the northeastern United States.