伊豆諸島鳥島のクロアシアホウドリのコロニーにみるCarios (Ornithodoros) capensisの生息状況およびその疫学調査

抄録

Ticks often carry infectious pathogens, and ticks infected with pathogens can be transmitted to seabirds. In May 1999, a project team member contracted a fever after being bitten by a tick during a field survey of albatrosses on Tori-shima. The researcher was bitten while in the main part of the Black-footed Albatross D. nigripes colony. Serodiagnosis indicated that the patient had been affected with borreliosis. The tick species involved was collected on Tori-shima and identified (based on its morphology) as the soft tick Carios (Ornithodoros) capensis.
A survey was carried out on Tori-shima in March and May 2000 in order to isolate the spirochete from the soft tick C. (O.) capensis, the host albatross D. nigripes and the Roof Rat Rattus rattus. We were unable to isolate Borrelia from either C. (O.) capensis, from blood or from the skin of the underside of the feet of D. nigripes, or from the ears or bladder of R. rattus. Nevertheless, ticks can be a negative factor affecting seabird reproduction. We report on the ecological status of C. (O.) capensis on Tori-shima, describe the relationship between this tick species and the various host animals on the island, and propose that surveys for ticks in seabird breeding colonies are very importance.