Volume 75, Issue 4
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645


, particularly the nymphal life stage, is the primary vector to humans of the Lyme disease agent in California. During 2004, we collected nymphs from 78 woodland sites in ecologically diverse Mendocino County, which has a moderately high incidence of Lyme disease. Within this county, nymphal density was elevated in forested areas with a growing degree day range of 2,600–3,000 (10°C base). Using a geographic information systems approach, we identified all areas in California sharing these environmental characteristics and thus projected to pose high acarologic risk of exposure to host-seeking nymphal ticks. Such areas were most commonly detected in the northwestern part of the state and along the Sierra Nevada foothills in the northeast, but the analysis also identified isolated areas with high acarologic risk in southern California. This mirrors the spatial distribution of endemic Lyme disease during 1993–2005; most cases occurred in counties to the northwest (58%) or northeast (26%), whereas fewer cases were reported from southern California (16%). Southern zip-codes from which Lyme disease cases had been reported were commonly located in close proximity to areas with high projected acarologic risk. Overall, Lyme disease incidence in zip code areas containing habitat with high projected acarologic risk was 10-fold higher than in zip code areas lacking such habitat and 27 times higher than for zip code areas without this habitat type within 50 km. A comparison of spatial Lyme disease incidence patterns based on county versus zip code units showed that calculating and displaying disease incidence at the zip code scale is a useful method to detect small, isolated areas with elevated disease risk that otherwise may go undetected.


Article metrics loading...

The graphs shown below represent data from March 2017
Loading full text...

Full text loading...



  1. Clover JR, Lane RS, 1995. Evidence implicating nymphal Ixodes pacificus (Acari: Ixodidae) in the epidemiology of Lyme disease in California. Am J Trop Med Hyg 53 : 237–240. [Google Scholar]
  2. Lane RS, Lavoie PE, 1988. Lyme borreliosis in California. Acarological, clinical and epidemiological studies. Ann N Y Acad Sci 539 : 192–203. [Google Scholar]
  3. Eisen RJ, Mun J, Eisen L, Lane RS, 2004. Life stage-related differences in density of questing ticks and infection with Borrelia burgdorferi sensu lato within a single cohort of Ixodes pacificus (Acari: Ixodidae). J Med Entomol 41 : 768–773. [Google Scholar]
  4. Lane RS, Foley JE, Eisen L, Lennette ET, Peot MA, 2001. Acarologic risk of exposure to emerging tick-borne bacterial pathogens in a semirural community in northern California. Vector Borne Zoonotic Dis 1 : 197–210. [Google Scholar]
  5. Ley C, Olshen EM, Reingold AL, 1995. Case-control study of risk factors for incident Lyme disease in California. Am J Epidemiol 142 : S39–S47. [Google Scholar]
  6. Monsen SE, Hazeltine WE, Henderson TL, Bronson LR, Tucker JR, Smith CR, 1990. Lyme borreliosis surveillance in Butte County, California. Bull Soc Vector Ecol 15 : 63–72. [Google Scholar]
  7. Ley C, Davila IH, Mayer NM, Murray RA, Rutherford GW, Reingold AL, 1994. Lyme disease in northwestern coastal California. West J Med 160 : 534–539. [Google Scholar]
  8. Lane RS, 1990. Seasonal activity of two human-biting ticks. Calif Agric 44 : 23–25. [Google Scholar]
  9. Lane RS, 1996. Risk of human exposure to vector ticks (Acari: Ixodidae) in a heavily used recreational area in northern California. Am J Trop Med Hyg 55 : 165–173. [Google Scholar]
  10. Kramer VL, Beesley C, 1993. Temporal and spatial distribution of Ixodes pacificus and Dermacentor occidentalis (Acari: Ixodidae) and prevalence of Borrelia burgdorferi in Contra Costa County, California. J Med Entomol 30 : 549–554. [Google Scholar]
  11. Eisen L, Eisen RJ, Lane RS, 2002. Seasonal activity patterns of Ixodes pacificus nymphs in relation to climatic conditions. Med Vet Entomol 16 : 235–244. [Google Scholar]
  12. Eisen RJ, Eisen L, Castro MB, Lane RS, 2003. Environmentally related variability in risk of exposure to Lyme disease spirochetes in northern California: Effect of climatic conditions and habitat type. Environ Entomol 32 : 1010–1018. [Google Scholar]
  13. Eisen L, Eisen RJ, Chang CC, Mun J, Lane RS, 2004. Acarologic risk of exposure to Borrelia burgdorferi spirochaetes: Long-term evaluations in north-western California, with implications for Lyme borreliosis risk-assessment models. Med Vet Entomol 18 : 38–49. [Google Scholar]
  14. Eisen RJ, Eisen L, Lane RS, 2006. 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. Am J Trop Med Hyg 74 : 632–640. [Google Scholar]
  15. Lane RS, Steinlein DB, Mun J, 2004. Human behaviors elevating exposure to Ixodes pacificus (Acari: Ixodidae) nymphs and their associated bacterial zoonotic agents in a hardwood forest. J Med Entomol 41 : 239–248. [Google Scholar]
  16. Tälleklint-Eisen L, Lane RS, 2000. Spatial and temporal variation in the density of Ixodes pacificus (Acari: Ixodidae) nymphs. Environ Entomol 29 : 272–280. [Google Scholar]
  17. Fritz CL, Vugia DJ, 2001. Clinical issues in Lyme borreliosis: a California perspective. Infect Dis Rev 3 : 111–122. [Google Scholar]
  18. Sall J, Creighton L, Lehman A, 2005. JMP Start Statistics. Third Edition. Belmont, CA: Brooks/Cole.
  19. Brownstein JS, Holford TR, Fish D, 2003. A climate-based model predicts the spatial distribution of the Lyme disease vector Ixodes scapularis in the United States. Environ Health Perspect 111 : 1152–1157. [Google Scholar]
  20. Bunnell JE, Price SD, Das A, Shields TM, Glass GE, 2003. Geographic information systems and spatial analysis of adult Ixodes scapularis (Acari: Ixodidae) in the Middle Atlantic region of the U.S.A. J Med Entomol 40 : 570–576. [Google Scholar]
  21. Estrada-Peña A, 1998. Geostatistics and remote sensing as predictive tools of tick distribution: A cokriging system to estimate Ixodes scapularis (Acari: Ixodidae) habitat suitability in the United States and Canada from advanced very high resolution radiometer satellite imagery. J Med Entomol 35 : 989–995. [Google Scholar]
  22. Guerra M, Walker E, Jones C, Paskewitz S, Cortinas MR, Stancil A, Beck L, Bobo M, Kitron U, 2002. Predicting the risk of Lyme disease: Habitat suitability for Ixodes scapularis in the north central United States. Emerg Infect Dis 8 : 289–297. [Google Scholar]
  23. Kitron U, Bouseman JK, Jones CJ, 1991. Use of the ARC/INFO GIS to study the distribution of Lyme disease ticks in an Illinois county. Prev Vet Med 11 : 243–248. [Google Scholar]
  24. Dister SW, Fish D, Bros SM, Frank DH, Wood BL, 1997. Landscape characterization of peridomestic risk for Lyme disease using satellite imagery. Am J Trop Med Hyg 57 : 687–692. [Google Scholar]
  25. Glass GE, Schwartz BS, Morgan JM III, Johnson DT, Noy PM, Israel E, 1995. Environmental risk factors for Lyme disease identified with geographic information systems. Am J Public Health 85 : 944–948. [Google Scholar]
  26. Guerra MA, Walker ED, Kitron U, 2001. Canine surveillance system for Lyme borreliosis in Wisconsin and northern Illinois: geographic distribution and risk factor analysis. Am J Trop Med Hyg 65 : 546–552. [Google Scholar]
  27. Kitron U, Kazmierczak JJ, 1997. Spatial analysis of the distribution of Lyme disease in Wisconsin. Am J Epidemiol 145 : 558–566. [Google Scholar]
  28. Meyers HB, Moore DF, Gellert G, Euler GL, Prendergast TJ, Badri M, Webb JP, Fogarty CL, 1992. Isolation of Borrelia burgdorferi from ticks in southern California. West J Med 157 : 455–456. [Google Scholar]
  29. Schwan TG, Schrumpf ME, Karstens RH, Clover JR, Wong J, Daugherty M, Struthers M, Rosa PA, 1993. Distribution and molecular analysis of Lyme disease spirochetes, Borrelia burgdorferi, isolated from ticks throughout California. J Clin Microbiol 31 : 3096–3108. [Google Scholar]
  30. Postic D, Marti-Ras N, Lane RS, Hendon M, Baranton G, 1998. Expanded diversity among Californian Borrelia isolates and description of Borrelia bissettii sp. nov. (formerly Borrelia group DN127). J Clin Microbiol 36 : 3497–3504. [Google Scholar]
  31. Vredevoe LK, Stevens JR, Schneider BS, 2004. Detection and characterization of Borrelia bissettii in rodents from the central California coast. J Med Entomol 41 : 736–745. [Google Scholar]
  32. Lane RS, Mun J, Eisen RJ, Eisen L, 2005. Western gray squirrel (Rodentia: Sciuridae): A primary reservoir host of Borrelia burgdorferi in Californian oak woodlands? J Med Entomol 42 : 388–396. [Google Scholar]

Data & Media loading...

  • Received : 24 Mar 2006
  • Accepted : 20 May 2006

Most Cited This Month

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error