LYME DISEASE IN WESTERN USA: ECOLOGY AND EPIDEMIOLOGY

Summary

Principal Investigator: Robert S Lane
Affiliation: University of California
Country: USA
Abstract: The broad objectives of this research are to clarify the role of the western gray squirrel (Sciurus griseus) as a keystone species for maintaining enzootic foci of the Lyme disease (LD) spirochete Borrelia burgdorferf sensu stricto (Bb ss) in the far-western USA; to investigate the host-seeking behavior of Ixodes pacificus (Ip) nymphs in relation to environmental parameters and to risk of human exposure to Bb ss; to ascertain what genospecies of Bb sensu lato (si) and other emerging bacterial zoonotic agents (e.g., Anaplasma phagocytophilum [Ap]) infect humans and their clinical correlates; and to complete the molecular and modeling components of an ongoing study to predict the risk of human exposure to Ip nymphs in dense woodlands of northwestern California. The reservoir competence of S. griseus for Bb ss and Ap will be evaluated by determining the infectivity of naturally infected squirrels for uninfected Ip larvae; the capacity of fed larvae to pass infection transstadially; the ability of infected nymphs to transmit infection to naive squirrels; the duration of infectivity in experimentally infected squirrels; and, in part, the geographic range of infected squirrels. The host-seeking activities of Ip nymphs in relation to biotic and abiotic factors will be investigated in woodlands where humans are at elevated risk of exposure to this life stage. These will include the diurnal questing cycle; the densities of host-seeking nymphs, and of Bb ss- or Ap-infected nymphs, on logs and tree trunks versus adjacent leaf litter; and the movements of marked ticks, and the frequency with which lizards encounter them after their release on logs versus leaf litter. The high diversity of Bb si in the Far West begs the question, which genospecies besides Bb ss can infect and cause human illness? Accordingly, serum specimens from hundreds of LD patients will be assayed molecularly for Bb si and co- infections with Ap or Bartonella spp. A stepwise multiple regression model for human exposure to Bb ss- infected Ip nymphs will be created after -5,500 Ip nymphs collected from 78 woodland sites have been tested by PCR. Development of this risk model, which culminates over 2 decades of intensive study, should contribute significantly to our knowledge of the landscape ecology and epidemiology of LD in this region.
Funding Period: 1985-09-01 - 2009-02-28
more information: NIH RePORT

Top Publications

  1. pmc Impacts of an introduced forest pathogen on the risk of Lyme disease in California
    Andrea Swei
    Department of Laboratory Medicine, University of California San Francisco, San Francisco, California, USA
    Vector Borne Zoonotic Dis 12:623-32. 2012
  2. pmc Differences in prevalence of Borrelia burgdorferi and Anaplasma spp. infection among host-seeking Dermacentor occidentalis, Ixodes pacificus, and Ornithodoros coriaceus ticks in northwestern California
    Robert S Lane
    Dept of Environmental Science, Policy and Management, University of California, Berkeley, California 94720, USA
    Ticks Tick Borne Dis 1:159-67. 2010
  3. pmc Distribution of the Lyme disease spirochete Borrelia burgdorferi in naturally and experimentally infected western gray squirrels (Sciurus griseus)
    Sarah Leonhard
    Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720, USA
    Vector Borne Zoonotic Dis 10:441-6. 2010
  4. pmc Horizontal and vertical movements of host-seeking Ixodes pacificus (Acari: Ixodidae) nymphs in a hardwood forest
    Robert S Lane
    Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA
    J Vector Ecol 34:252-66. 2009
  5. ncbi Community ecology and disease risk: lizards, squirrels, and the Lyme disease spirochete in California, USA
    Daniel J Salkeld
    Department of Environmental Science, Policy and Management, University of California, Berkeley, California 94720, USA
    Ecology 91:293-8. 2010
  6. pmc Transmission cycles of Borrelia burgdorferi and B. bissettii in relation to habitat type in northwestern California
    Lars Eisen
    Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523, USA
    J Vector Ecol 34:81-91. 2009
  7. pmc A spatially-explicit model of acarological risk of exposure to Borrelia burgdorferi-infected Ixodes pacificus nymphs in northwestern California based on woodland type, temperature, and water vapor
    Rebecca J Eisen
    Division of Vector Borne Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, USA
    Ticks Tick Borne Dis 1:35-43. 2010
  8. ncbi Coinfection of western gray squirrel (Sciurus griseus) and other sciurid rodents with Borrelia burgdorferi sensu stricto and Anaplasma phagocytophilum in California
    Nathan C Nieto
    Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California 95616, USA
    J Wildl Dis 46:291-6. 2010
  9. pmc Population structure of the lyme borreliosis spirochete Borrelia burgdorferi in the western black-legged tick (Ixodes pacificus) in Northern California
    Yvette A Girard
    University of California Berkeley, Department of Environmental Science, Policy and Management, 137 Mulford Hall 3114, Berkeley, CA 94720 3114, USA
    Appl Environ Microbiol 75:7243-52. 2009
  10. pmc Identifying the reservoir hosts of the Lyme disease spirochete Borrelia burgdorferi in California: the role of the western gray squirrel (Sciurus griseus)
    Daniel J Salkeld
    Department of Environmental Science, Policy and Management, and Office of Laboratory Animal Care, University of California, Berkeley, California 94720, USA
    Am J Trop Med Hyg 79:535-40. 2008

Scientific Experts

Detail Information

Publications21

  1. pmc Impacts of an introduced forest pathogen on the risk of Lyme disease in California
    Andrea Swei
    Department of Laboratory Medicine, University of California San Francisco, San Francisco, California, USA
    Vector Borne Zoonotic Dis 12:623-32. 2012
    ..This study underscores the important direct and indirect impacts of invasive plant pathogens on biodiversity, the transmission cycles of zoonotic diseases, and ultimately human health...
  2. pmc Differences in prevalence of Borrelia burgdorferi and Anaplasma spp. infection among host-seeking Dermacentor occidentalis, Ixodes pacificus, and Ornithodoros coriaceus ticks in northwestern California
    Robert S Lane
    Dept of Environmental Science, Policy and Management, University of California, Berkeley, California 94720, USA
    Ticks Tick Borne Dis 1:159-67. 2010
    ..phagocytophilum. This suggests that the distribution of this rickettsia is highly focal or variable from year-to-year within this particular woodland...
  3. pmc Distribution of the Lyme disease spirochete Borrelia burgdorferi in naturally and experimentally infected western gray squirrels (Sciurus griseus)
    Sarah Leonhard
    Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720, USA
    Vector Borne Zoonotic Dis 10:441-6. 2010
    ..Since spirochetes could be detected in squirrels 7-21 months postinfection, we conclude that S. griseus can infect Ixodes pacificus ticks with B. burgdorferi s.s. trans-seasonally...
  4. pmc Horizontal and vertical movements of host-seeking Ixodes pacificus (Acari: Ixodidae) nymphs in a hardwood forest
    Robert S Lane
    Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA
    J Vector Ecol 34:252-66. 2009
    ..burgdorferi-infected nymphs are as likely to move horizontally as vertically when offered a choice...
  5. ncbi Community ecology and disease risk: lizards, squirrels, and the Lyme disease spirochete in California, USA
    Daniel J Salkeld
    Department of Environmental Science, Policy and Management, University of California, Berkeley, California 94720, USA
    Ecology 91:293-8. 2010
    ..Species identity is therefore critical in understanding and determining the local disease ecology...
  6. pmc Transmission cycles of Borrelia burgdorferi and B. bissettii in relation to habitat type in northwestern California
    Lars Eisen
    Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523, USA
    J Vector Ecol 34:81-91. 2009
    ..burgdorferi in certain woodlands offers intriguing opportunities for preventing Lyme disease by targeting these animals by means of either host-targeted acaricides or oral vaccination against B. burgdorferi...
  7. pmc A spatially-explicit model of acarological risk of exposure to Borrelia burgdorferi-infected Ixodes pacificus nymphs in northwestern California based on woodland type, temperature, and water vapor
    Rebecca J Eisen
    Division of Vector Borne Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, USA
    Ticks Tick Borne Dis 1:35-43. 2010
    ....
  8. ncbi Coinfection of western gray squirrel (Sciurus griseus) and other sciurid rodents with Borrelia burgdorferi sensu stricto and Anaplasma phagocytophilum in California
    Nathan C Nieto
    Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California 95616, USA
    J Wildl Dis 46:291-6. 2010
    ....
  9. pmc Population structure of the lyme borreliosis spirochete Borrelia burgdorferi in the western black-legged tick (Ixodes pacificus) in Northern California
    Yvette A Girard
    University of California Berkeley, Department of Environmental Science, Policy and Management, 137 Mulford Hall 3114, Berkeley, CA 94720 3114, USA
    Appl Environ Microbiol 75:7243-52. 2009
    ..The differences in B. burgdorferi population structure in California ticks compared to the Northeast emphasize the need for a greater understanding of the genetic diversity of spirochetes infecting California LB patients...
  10. pmc Identifying the reservoir hosts of the Lyme disease spirochete Borrelia burgdorferi in California: the role of the western gray squirrel (Sciurus griseus)
    Daniel J Salkeld
    Department of Environmental Science, Policy and Management, and Office of Laboratory Animal Care, University of California, Berkeley, California 94720, USA
    Am J Trop Med Hyg 79:535-40. 2008
    ..burgdorferi trans-seasonally. Non-native eastern gray squirrels (Sciurus carolinensis) and fox squirrels (Sciurus niger) were infrequently infected with B. burgdorferi...
  11. ncbi Host-seeking behavior of Ixodes pacificus (Acari: Ixodidae) nymphs in relation to environmental parameters in dense-woodland and woodland-grass habitats
    Robert S Lane
    Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA
    J Vector Ecol 32:342-57. 2007
    ..Individuals having prolonged contact with logs or trunks in spring would be well advised to employ personal protective measures to minimize exposure to I. pacificus nymphs and their attendant bacterial zoonotic agents...
  12. ncbi Ability of transstadially infected Ixodes pacificus (Acari: Ixodidae) to transmit West Nile virus to song sparrows or western fence lizards
    W K Reisen
    Center for Vectorborne Diseases and Department of Pathology, Immunology, and Microbiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
    J Med Entomol 44:320-7. 2007
    ..2 to 5.6 log10 PFU/ml. Our data and data from previous studies collectively indicated that ixodid ticks were not able to experimentally transmit WNV and therefore most likely would not be important vectors in WNV transmission cycles...
  13. ncbi Western gray squirrel (Rodentia: Sciuridae): a primary reservoir host of Borrelia burgdorferi in Californian oak woodlands?
    Robert S Lane
    Division of Insect Biology, Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA
    J Med Entomol 42:388-96. 2005
    ..burgdorferi s.s. in certain types of woodlands. The findings with respect to A. phagocytophilum, although of less certain significance, suggest that S. griseus could serve as a secondary host of this rickettsia...
  14. pmc Phylogenetic analysis of the spirochetes Borrelia parkeri and Borrelia turicatae and the potential for tick-borne relapsing fever in Florida
    Tom G Schwan
    Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South 4th St, Hamilton, MT 59840, USA
    J Clin Microbiol 43:3851-9. 2005
    ..turicatae but only linear plasmids in B. parkeri, which should be of interest to investigators concerned with plasmid diversity and evolution within this group of spirochetes...
  15. ncbi Predicting density of Ixodes pacificus nymphs in dense woodlands in Mendocino County, California, based on geographic information systems and remote sensing versus field-derived data
    Rebecca J Eisen
    Division of Vector Borne Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado 80522, USA
    Am J Trop Med Hyg 74:632-40. 2006
    ..5 nymphs per 100 m(2); 1.7% of the county) tended to cluster in the central interior and most heavily populated region of Mendocino County, but were rare in the proximity of coastal population centers...
  16. ncbi Geographical distribution patterns and habitat suitability models for presence of host-seeking ixodid ticks in dense woodlands of Mendocino County, California
    L Eisen
    Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA
    J Med Entomol 43:415-27. 2006
    ..The model equations were used to create spatial surfaces of predicted presence of suitable habitat for openly host-seeking ticks in Mendocino County dense woodlands...
  17. ncbi Sylvatic maintenance of Borrelia burgdorferi (Spirochaetales) in Northern California: untangling the web of transmission
    R N Brown
    Department of Wildlife, Humboldt State University, Arcata, CA 95521, USA
    J Med Entomol 43:743-51. 2006
    ..burgdorferi s.s. in Californian oak woodlands, suggest that our earlier hypothesis implicating an enzootic cycle involving woodrats and I. spinipalpis is insufficient to account for observed patterns of infection in nature...
  18. ncbi Refractoriness of the western fence lizard (Sceloporus occidentalis) to the Lyme disease group spirochete Borrelia bissettii
    R S Lane
    Division of Insect Biology, Department of Environmental Science, Policy and Management, University of California, Berkeley, California 94720, USA
    J Parasitol 92:691-6. 2006
    ..burgdorferi sensu lato spirochetes present in tissues of attached and feeding I. pacificus nymphs, thereby potentially reducing the probability of transmission of these bacteria to humans or other animals by the resultant adult ticks...
  19. ncbi Spatial patterns of Lyme disease risk in California based on disease incidence data and modeling of vector-tick exposure
    Rebecca J Eisen
    Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA
    Am J Trop Med Hyg 75:669-76. 2006
    ....
  20. ncbi Wild turkey (Meleagris gallopavo) as a host of ixodid ticks, lice, and Lyme disease spirochetes (Borrelia burgdorferi sensu lato) in California state parks
    Robert S Lane
    Department of Environmental Science, Policy and Management, 137 Mulford Hall, University of California, Berkeley, California 94720, USA
    J Wildl Dis 42:759-71. 2006
    ..Taken together, these findings indicate that wild turkeys are important avian hosts of I. pacificus nymphs, but they appear to be inconsequential hosts of B. burgdorferi s.l...
  21. ncbi Columbian black-tailed deer (Odocoileus hemionus columbianus) as hosts for Borrelia spp. in northern California
    Robert S Lane
    Division of Insect Biology, University of California, Berkeley, California 94720, USA
    J Wildl Dis 41:115-25. 2005
    ..g., immunoblotting, PCR/sequencing analysis)...