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Eisen L, Saunders MEM, Kramer VL, Eisen RJ. History of the geographic distribution of the western blacklegged tick, Ixodes pacificus, in the United States. Ticks Tick Borne Dis 2024; 15:102325. [PMID: 38387162 PMCID: PMC10960675 DOI: 10.1016/j.ttbdis.2024.102325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 02/02/2024] [Accepted: 02/15/2024] [Indexed: 02/24/2024]
Abstract
Ixodes pacificus (the western blacklegged tick) occurs in the far western United States (US), where it commonly bites humans. This tick was not considered a species of medical concern until it was implicated in the 1980s as a vector of Lyme disease spirochetes. Later, it was discovered to also be the primary vector to humans in the far western US of agents causing anaplasmosis and hard tick relapsing fever. The core distribution of I. pacificus in the US includes California, western Oregon, and western Washington, with outlier populations reported in Utah and Arizona. In this review, we provide a history of the documented occurrence of I. pacificus in the US from the 1890s to present, and discuss associations of its geographic range with landscape, hosts, and climate. In contrast to Ixodes scapularis (the blacklegged tick) in the eastern US, there is no evidence for a dramatic change in the geographic distribution of I. pacificus over the last half-century. Field surveys in the 1930s and 1940s documented I. pacificus along the Pacific Coast from southern California to northern Washington, in the Sierra Nevada foothills, and in western Utah. County level collection records often included both immatures and adults of I. pacificus, recovered by drag sampling or from humans, domestic animals, and wildlife. The estimated geographic distribution presented for I. pacificus in 1945 by Bishopp and Trembley is similar to that presented in 2022 by the Centers for Disease Control and Prevention. There is no clear evidence of range expansion for I. pacificus, separate from tick records in new areas that could have resulted from newly initiated or intensified surveillance efforts. Moreover, there is no evidence from long-term studies that the density of questing I. pacificus ticks has increased over time in specific areas. It therefore is not surprising that the incidence of Lyme disease has remained stable in the Pacific Coast states from the early 1990s, when it became a notifiable condition, to present. We note that deforestation and deer depredation were less severe in the far western US during the 1800s and early 1900s compared to the eastern US. This likely contributed to I. pacificus maintaining stable, widespread populations across its geographic range in the far western US in the early 1900s, while I. scapularis during the same time period appears to have been restricted to a small number of geographically isolated refugia sites within its present range in the eastern US. The impact that a warming climate may have had on the geographic distribution and local abundance of I. pacificus in recent decades remains unclear.
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Affiliation(s)
- Lars Eisen
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, United States.
| | - Megan E M Saunders
- Vector-Borne Disease Section, California Department of Public Health, 1616 Capitol Ave, Sacramento, CA 95814, United States
| | - Vicki L Kramer
- Vector-Borne Disease Section, California Department of Public Health, 1616 Capitol Ave, Sacramento, CA 95814, United States
| | - Rebecca J Eisen
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, United States
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Newman EA, Eisen L, Eisen RJ, Fedorova N, Hasty JM, Vaughn C, Lane RS. Borrelia burgdorferi sensu lato spirochetes in wild birds in northwestern California: associations with ecological factors, bird behavior and tick infestation. PLoS One 2015; 10:e0118146. [PMID: 25714376 PMCID: PMC4340631 DOI: 10.1371/journal.pone.0118146] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 01/05/2015] [Indexed: 11/26/2022] Open
Abstract
Although Borrelia burgdorferi sensu lato (s.l.) are found in a great diversity of vertebrates, most studies in North America have focused on the role of mammals as spirochete reservoir hosts. We investigated the roles of birds as hosts for subadult Ixodes pacificus ticks and potential reservoirs of the Lyme disease spirochete B. burgdorferi sensu stricto (s.s.) in northwestern California. Overall, 623 birds representing 53 species yielded 284 I. pacificus larvae and nymphs. We used generalized linear models and zero-inflated negative binomial models to determine associations of bird behaviors, taxonomic relationships and infestation by I. pacificus with borrelial infection in the birds. Infection status in birds was best explained by taxonomic order, number of infesting nymphs, sampling year, and log-transformed average body weight. Presence and counts of larvae and nymphs could be predicted by ground- or bark-foraging behavior and contact with dense oak woodland. Molecular analysis yielded the first reported detection of Borrelia bissettii in birds. Moreover, our data suggest that the Golden-crowned Sparrow (Zonotrichia atricapilla), a non-resident species, could be an important reservoir for B. burgdorferi s.s. Of 12 individual birds (9 species) that carried B. burgdorferi s.l.-infected larvae, no birds carried the same genospecies of B. burgdorferi s.l. in their blood as were present in the infected larvae removed from them. Possible reasons for this discrepancy are discussed. Our study is the first to explicitly incorporate both taxonomic relationships and behaviors as predictor variables to identify putative avian reservoirs of B. burgdorferi s.l. Our findings underscore the importance of bird behavior to explain local tick infestation and Borrelia infection in these animals, and suggest the potential for bird-mediated geographic spread of vector ticks and spirochetes in the far-western United States.
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Affiliation(s)
- Erica A. Newman
- Energy and Resources Group, University of California, 310 Barrows Hall, Berkeley, CA 94720, United States of America
- Department of Environmental Science, Policy, and Management, University of California, 130 Mulford Hall, Berkeley, CA 94720, United States of America
| | - Lars Eisen
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado 80523, United States of America
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado 80522, United States of America
| | - Rebecca J. Eisen
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado 80522, United States of America
| | - Natalia Fedorova
- Department of Environmental Science, Policy, and Management, University of California, 130 Mulford Hall, Berkeley, CA 94720, United States of America
| | - Jeomhee M. Hasty
- Hawaii Department of Health, Sanitation Branch, Vector Control, Honolulu, Hawaii 96813, United States of America
| | - Charles Vaughn
- University of California Hopland Research & Extension Center, Hopland, CA 95449, United States of America
| | - Robert S. Lane
- Department of Environmental Science, Policy, and Management, University of California, 130 Mulford Hall, Berkeley, CA 94720, United States of America
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Dingler RJ, Wright SA, Donohue AM, Macedo PA, Foley JE. Surveillance for Ixodes pacificus and the tick-borne pathogens Anaplasma phagocytophilum and Borrelia burgdorferi in birds from California's Inner Coast Range. Ticks Tick Borne Dis 2014; 5:436-45. [PMID: 24690191 DOI: 10.1016/j.ttbdis.2014.02.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 02/02/2014] [Accepted: 02/06/2014] [Indexed: 11/25/2022]
Abstract
We investigated the involvement of birds in the ecology of the western black-legged tick, Ixodes pacificus, and its associated zoonotic bacteria, Borrelia burgdorferi and Anaplasma phagocytophilum, at two interior coast-range study sites in northern California. Anaplasma phagocytophilum, the agent of granulocytic anaplasmosis (GA), and B. burgdorferi s.s., the agent of Lyme disease (LD), are tick-borne pathogens that are well established in California. We screened blood and ticks from 349 individual birds in 48 species collected in 2011 and 2012 using pathogen-specific PCR. A total of 617 immature I. pacificus was collected with almost three times as many larvae than nymphs. There were 7.5 times more I. pacificus at the Napa County site compared to the Yolo County site. Two of 74 (3%) nymphal pools from an Oregon junco (Junco hyemalis) and a hermit thrush (Catharus guttatus) and 4 individual larvae (all from Oregon juncos) were PCR-positive for B. burgdorferi. Blood samples from a golden-crowned sparrow (Zonotrichia atricapilla) and a European starling (Sturnus vulgaris) were positive for A. phagocytophilum DNA at very low levels. Birds that forage on ground or bark and nest on the ground, as well as some migratory species, are at an increased risk for acquiring I. pacificus. Our findings show that birds contribute to the ecologies of LD and GA in California by serving as a blood-meal source, feeding and transporting immature I. pacificus, and sometimes as a source of Borrelia infection.
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Affiliation(s)
- Regina J Dingler
- Department of Medicine and Epidemiology, 1320 Tupper Hall, School of Veterinary Medicine, University of California, Davis, USA
| | - Stan A Wright
- Sacramento-Yolo Mosquito & Vector Control District, 8631 Bond Road, Elk Grove, CA 95624, USA
| | - Ann M Donohue
- Napa Mosquito Abatement District, 15 Melvin Road, American Canyon, CA 94503, USA
| | - Paula A Macedo
- Sacramento-Yolo Mosquito & Vector Control District, 8631 Bond Road, Elk Grove, CA 95624, USA
| | - Janet E Foley
- Department of Medicine and Epidemiology, 1320 Tupper Hall, School of Veterinary Medicine, University of California, Davis, USA.
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Margos G, Hojgaard A, Lane RS, Cornet M, Fingerle V, Rudenko N, Ogden N, Aanensen DM, Fish D, Piesman J. Multilocus sequence analysis of Borrelia bissettii strains from North America reveals a new Borrelia species, Borrelia kurtenbachii. Ticks Tick Borne Dis 2011; 1:151-8. [PMID: 21157575 DOI: 10.1016/j.ttbdis.2010.09.002] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using multilocus sequence analyses (MLSA), we investigated the phylogenetic relationship of spirochaete strains from North America previously assigned to the genospecies Borrelia bissettii. We amplified internal fragments of 8 housekeeping genes (clpA, clpX, nifS, pepX, pyrG, recG, rplB, and uvrA) located on the main linear chromosome by polymerase chain reaction. Phylogenetic analysis of concatenated sequences of the 8 loci showed that the B. bissettii clade consisted of 4 closely related clusters which included strains from California (including the type strain DN127-Cl9-2/p7) and Colorado that were isolated from Ixodes pacificus, I. spinipalpis, or infected reservoir hosts. Several strains isolated from I. scapularis clustered distantly from B. bissettii. Genetic distance analyses confirmed that these strains are more distant to B. bissettii than they are to B. carolinensis, a recently described Borrelia species, which suggests that they constitute a new Borrelia genospecies. We propose that it be named Borrelia kurtenbachii sp. nov. in honour of the late Klaus Kurtenbach. The data suggest that ecological differences between B. bissettii and the new Borrelia genospecies reflect different transmission cycles. In view of these findings, the distinct vertebrate host-tick vector associations and the distributions of B. bissettii and B. kurtenbachii require further investigation.
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Affiliation(s)
- Gabriele Margos
- University of Bath, Department of Biology and Biochemistry, Claverton Down, Bath BA2 7AY, UK.
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Slowik TJ, Lane RS. Feeding preferences of the immature stages of three western north American ixodid ticks (Acari) for avian, reptilian, or rodent hosts. JOURNAL OF MEDICAL ENTOMOLOGY 2009; 46:115-122. [PMID: 19198525 DOI: 10.1603/033.046.0115] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Larval and nymphal Ixodes pacificus Cooley and Kohls, I. (Ixodes) jellisoni Cooley and Kohls, and Dermacentor occidentalis Marx were tested for host preference when simultaneously presented with a deer mouse (Peromyscus maniculatus Wagner), California kangaroo rat (Dipodomys californicus Merriam), western fence lizard (Sceloporus occidentalis Baird and Girard), and California towhee (Pipilo crissalis Vigors) in an experimental apparatus. Differences were observed in the preferences among the three species and between life stages. More larvae of all species approached and contacted hosts than did nymphs. Subadult I. pacificus entered all host-containing chambers in the highest numbers and remained on lizards most often after contact. Subadult I. jellisoni entered and remained in the chambers containing kangaroo rats, while rejecting mice, lizards, and birds as hosts. Subadult D. occidentalis most frequently entered rodent-containing chambers and contacted these hosts. After overnight exposure to all nonavian hosts, only I. pacificus parasitized and fed successfully on all three animals. I. jellisoni fed only on kangaroo rats and D. occidentalis fed only on rodents. Molting success ranged from approximately 66 to 95% among tick species and stages. We concluded that, under laboratory conditions, I. pacificus larvae and nymphs prefer western fence lizards, but also will parasitize rodents. Dermacentor occidentalis immatures use deer mice and kangaroo rats similarly, whereas I. jellisoni subadults exclusively parasitize kangaroo rats. California towhees are considerably less attractive as hosts for these three ticks. These host preferences are consistent with what is known about the natural feeding habits of all three ticks.
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Affiliation(s)
- Ted J Slowik
- S&R Communications Group, 2511 Old Cornwallis Rd., Suite 200, Durham, NC 27713, USA.
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Comstedt P, Bergström S, Olsen B, Garpmo U, Marjavaara L, Mejlon H, Barbour AG, Bunikis J. Migratory passerine birds as reservoirs of Lyme borreliosis in Europe. Emerg Infect Dis 2006; 12:1087-95. [PMID: 16836825 PMCID: PMC3291064 DOI: 10.3201/eid1207.060127] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Birds host vector ticks and Borrelia species and vary in effectiveness as reservoirs. To define the role of birds as reservoirs and disseminators of Borrelia spirochetes, we characterized tick infestation and reservoir competence of migratory passerine birds in Sweden. A total of 1,120 immature Ixodes ricinus ticks were removed from 13,260 birds and assayed by quantitative polymerase chain reaction (PCR) for Borrelia, followed by DNA sequencing for species and genotype identification. Distributions of ticks on birds were aggregated, presumably because of varying encounters with ticks along migratory routes. Lyme borreliosis spirochetes were detected in 160 (14%) ticks. Borrelia garinii was the most common species in PCR-positive samples and included genotypes associated with human infections. Infestation prevalence with infected ticks was 5 times greater among ground-foraging birds than other bird species, but the 2 groups were equally competent in transmitting Borrelia. Migratory passerine birds host epidemiologically important vector ticks and Borrelia species and vary in effectiveness as reservoirs on the basis of their feeding behavior.
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Affiliation(s)
| | | | - Björn Olsen
- Umeå University, Umeå, Sweden
- Kalmar University, Kalmar, Sweden
| | - Ulf Garpmo
- Umeå University, Umeå, Sweden
- Kalmar Hospital, Kalmar, Sweden
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Wright SA, Lemenager DA, Tucker JR, Armijos MV, Yamamoto SA. An avian contribution to the presence of Ixodes pacificus (Acari: Ixodidae) and Borrelia burgdorferi on the Sutter Buttes of California. JOURNAL OF MEDICAL ENTOMOLOGY 2006; 43:368-74. [PMID: 16619623 DOI: 10.1603/0022-2585(2006)043[0368:aacttp]2.0.co;2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Birds from 45 species were sampled during three spring seasons from an isolated canyon on the Sutter Buttes in California for the presence of subadult stages of Ixodes pacificus Cooley & Kohls, and for infection with Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner. These birds were found to have an infestation prevalence of 45%, a density of 1.7 ticks per bird, and an intensity of 3.8 ticks per infested bird. There was a significant difference in the I. pacificus infestations between canopy and ground-dwelling birds. Birds also demonstrated an overall infection with B. burgdorferi of 6.4% with significant difference between bird species. Amplification and subsequent sequencing of the 23s-5s rRNA intergenic spacer region of the Borrelia genome from one bird, a hermit thrush, Catharus guttatus (Nuttall), showed that the infection in this bird was caused by B. burgdorferi sensu stricto; the first such finding in a bird from the far west. Our results suggest that birds play a role in the distribution and maintenance of I. pacificus, and possibly of B. burgdoferi, at the Sutter Buttes, CA.
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Affiliation(s)
- Stan A Wright
- Sacramento-Yolo Mosquito and Vector Control District, 8631 Bond Rd., Elk Grove, CA 95624, USA
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Eisen L, Eisen RJ, Lane RS. Geographical distribution patterns and habitat suitability models for presence of host-seeking ixodid ticks in dense woodlands of Mendocino County, California. JOURNAL OF MEDICAL ENTOMOLOGY 2006; 43:415-27. [PMID: 16619628 DOI: 10.1603/0022-2585(2006)043[0415:gdpahs]2.0.co;2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We used drag sampling to examine the geographical distribution patterns of ixodid ticks engaging in open (non-nidicolous) host-seeking behavior in dense woodland habitats of the climatically and ecologically diverse Mendocino County in north coastal California. The findings based on this sampling methodology reflect risk of human exposure to host-seeking ticks rather than the true distribution of the ticks. Drag sampling in 78 sites yielded 7,860 nymphal or adult Ixodes pacificus Cooley & Kohls, 220 Dermacentor occidentalis Marx, 150 Ixodes spinipalpis Hadwen & Nuttall, 15 Hemaphysalis leporispalustris (Packard), 12 Ixodes angustus Neumann, 12 Ixodes auritulus Neumann, and a single Dermacentor variabilis (Say). I. pacificus, which is the primary vector of the Lyme disease spirochete Borrelia burgdorferi to humans in California, occurred in all 78 sites examined. D. occidentalis, another tick species commonly biting humans in California, and H. leporispalustris typically were encountered in oak-associated woodlands in the central or eastern parts of the county. In contrast, three species of Ixodes ticks (I. angustus, I. auritulus, and I. spinipalpis) most commonly were found questing openly in woodlands with redwood present in the western part of the county. I. angustus and I. spinipalpis are occasional human biters and known experimental vectors of B. burgdorferi. Our study represents the first collection of large numbers of openly host-seeking I. spinipalpis ticks. Univariate tests of associations between presence of ticks (D. occidentalis, H. leporispalustris, I. angustus, I. auritulus, or I. spinipalpis) and environmental geographical information systems-remote sensing (GIS/ RS)-based data indicated that elevation, number of growing degree-days, and tasseled cap brightness, greenness, and wetness are especially useful predictors of presence of openly hostseeking ticks. Combinations of the above-mentioned GIS/RS-based data yielded significant logistic regression models for habitat suitability of host-seeking ticks for all five above-mentioned species. 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.
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Affiliation(s)
- L Eisen
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA
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Gryczyńska A, Zgódka A, Płoski R, Siemiatkowski M. Borrelia burgdorferisensu lato infection in passerine birds from the Mazurian Lake region (Northeastern Poland). Avian Pathol 2004; 33:69-75. [PMID: 14681070 DOI: 10.1080/03079450310001636309] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The aim of the present study was to evaluate a potential role of different passerine birds species in Mazurian Lake region (northeast Poland) in the spread of Borrelia burgdorferi sensu lato, the spirochaete that causes Lyme disease. A total number of 1254 birds (representing 42 species) were captured during the 3-year study period. Blood samples were collected from birds and analyzed with a nested polymerase chain reaction technique in order to detect fragments of the pathogen DNA. Positive results were obtained in 4.2% of all blood samples. Specifically, B. burgdorferi s.l. were detected in tree pipit (Anthus Erivialis; 21.1% of 19 birds), dunnock (Prunella modularis; 15.8% of 19 birds), chaffinch (Fringilla coelebs; 12.7% of 166 birds), song thrush (Turdus philometos; 9.3% of 54 birds), nuthatch (Sitta euopea; 7.7% of 26 birds), hawfinch (Coccothraustes coccothroustes; 6.7% of 15 birds), robin (Erithacus rebecula; 5.1% of 256 birds), blackbird (Turdus merula; 4.2% of 71 birds) and wren (Troglodytes troglodytes; 3.7% of 27 birds). Additionally, the incidence of the infection was analyzed in relation to the habitat in which the birds resided (mixed coniferous forest or alder swamp forest), months of the study (from April to October), age and sex, but the differences were not statistically significant.
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Affiliation(s)
- Alicja Gryczyńska
- Department of Ecology, Institute of Zoology, University of Warsaw, Banacha 2, 02-097 Warsaw, Porland.
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