TRANSHEMISPHERIC EXCHANGE OF LYME-DISEASE SPIROCHETES BY SEABIRDS

Lyme disease is a zoonosis transmitted by ticks and caused by the spir ochete Borrelia burgdorferi sensu late. Epidemiological and ecological investigations to date have focused on the terrestrial forms of Lyme disease. Here we show a significant role for seabirds in a global tran smission cycle by demonstrating the presence of Lyme disease Borrelia spirochetes in Ixodes uriae ticks from several seabird colonies in bot h the Southern and Northern Hemispheres, Borrelia DNA was isolated fro m I. uriae ticks and from cultured spirochetes. Sequence analysis of a conserved region of the flagellin (fla) gene revealed that the DNA ob tained was from B. garinii regardless of the geographical origin of th e sample, Identical fla gene fragments in ticks obtained from differen t hemispheres indicate a transhemispheric exchange of Lyme disease spi rochetes, A marine ecological niche and a marine epidemiological route for Lyme disease borreliae are proposed.