The Western Black-Legged Tick, Ixodes Pacificus: A Vector of Borrelia Burgdorferi

Willy Burgdorfer Department of Health and Human Services, Public Health Service, National Institutes of Health, National Institute of Allergy and Infectious Diseases, Epidemiology Branch, Rocky Mountain Laboratories, Hamilton, Montana 59840

Search for other papers by Willy Burgdorfer in
Current site
Google Scholar
PubMed
Close
,
Robert S. Lane Department of Entomological Sciences, University of California, Berkeley, California 94720

Search for other papers by Robert S. Lane in
Current site
Google Scholar
PubMed
Close
,
Alan G. Barbour Department of Health and Human Services, Public Health Service, National Institutes of Health, National Institute of Allergy and Infectious Diseases, Epidemiology Branch, Rocky Mountain Laboratories, Hamilton, Montana 59840

Search for other papers by Alan G. Barbour in
Current site
Google Scholar
PubMed
Close
,
Robert A. Gresbrink Field Services Section, Oregon State Health Division, Department of Human Resources, Portland, Oregon 97207

Search for other papers by Robert A. Gresbrink in
Current site
Google Scholar
PubMed
Close
, and
John R. Anderson Department of Entomological Sciences, University of California, Berkeley, California 94720

Search for other papers by John R. Anderson in
Current site
Google Scholar
PubMed
Close
Restricted access

To determine the significance of the western black-legged tick, Ixodes pacificus, as a vector of the Lyme disease spirochete, Borrelia burgdorferi, a tick/spirochete survey was conducted in northern California and southwestern Oregon from 1982 to 1984. Of 1,687 adult ticks collected off vegetation, 25 (1.48%) contained spirochetes. Of 715 ticks from Oregon, 14 (1.96%) were infected whereas 11 (1.13%) of 972 ticks from California harbored spirochetes

An isolate of 1 of the spirochetes reacted specifically when treated with monoclonal antibodies to B. burgdorferi. Polyacrylamide gel electrophoresis of a lysate of the isolate showed it to be nearly identical with 2 isolates of B. burgdorferi

Of the 25 infected I. pacificus, 17 had spirochetes in their midgut only; the remaining 8 ticks showed a generalized infection of all the tissues, with midgut, central ganglion and ovary or testes showing heavy spirochetal infections. Decreased immunofluorescent staining reactivity of spirochetes in tissues other than midgut in 6 of 8 I. pacificus with generalized infection may reflect adverse physiologic conditions for the development of spirochetes in the hemocele.

Author Notes

Save