BORRELIA-BURGDORFERI IN IXODES-DAMMINI (ACARI, IXODIDAE) FEEDING ON BIRDS IN LYME, CONNECTICUT, USA

Passerine birds were captured in Japanese mist nets in Lyme, Connecticut, during 1990 and 1991 to collect larva an nymphal Ixodes dammini and to identify potential bird reservoirs for Borrelia burgdorferi, the etiologic agent for Lyme borreliosis. Of the 3291 birds captured and recaptured (32 %), 503 in 35 species were parasitized by I. dammini. Ninety-eight of the recaptured birds had ticks attached. Borrelia burgdorferi was detected by indirect immunofluorescence staining in 72 (4.7 %) of 1518 larvae and in 114 (23.3 %) of 490 nymphs tested. Prevalence of infected larvae was comparatively greater for specimens removed from veeries (21.4 %, n = 140 tested), Carolina wrens (15.5 %, n = 84), hooded warblers (8.9 %, n = 79), and house wrens (8.6 %, n = 58). Based on the presence of infected larval ticks on birds, members of these 4 host species have the greatest potential for being reservoirs of B. burgdorferi. Relatively lower percentages of infected larvae (0. 3 - 6.7 %) were recorded for 8 other bird species. June through mid-August is a suitable time to isolate B. burgdorferi from natural populations of birds or ticks feeding on avian hosts.