Abstract
The hard tick Ixodes uriae parasitises a wide range of seabird species in the circumpolar areas of bothNorthern and Southern hemispheres and has been shown to be infected with Borrelia burgdorferi sensulato, the bacterial agents of Lyme borreliosis. Although it is assumed that seabirds represent viable reservoirhosts, direct demonstrations of infection are limited to a single study from the Northern hemisphere.Here, the blood of 50 tick-infested adult king penguins (Aptenodytes patagonicus halli) breeding in theCrozet Archipelago (Southern Indian Ocean) was examined for B. burgdorferi sl exposure by serology andfor spirochetemia by in vitro DNA amplification. Four birds were found positive by serology, whereas B.burgdorferi sl DNA was detected in two other birds. Our data therefore provide the first direct proof ofBorrelia burgdorferi sl spirochetes in seabirds of the Southern hemisphere and indicate a possible reservoirrole for king penguins in the natural maintenance of this bacterium. Although the bacterial geneticdiversity present in these hosts and the infectious period for tick vectors remain to be elucidated, ourresults add to a growing body of knowledge on the contribution of seabirds to the complex epizootiologyof Lyme disease and the global dissemination of B. burgdorferi sl spirochetes.