lyme the united states, lyme disease is the most common arthropod-borne infection. the majority of cases are reported from the northeast, the midwest, and california, which are areas with established foci of borrelia burgdorferi. advances in the understanding of the epidemiology of ixodes ticks, the established vector for transmission of lyme disease, provided strategies to reduce tick populations and the risk of acquiring disease. genotypic diversity of subspecies of b. burgdorferi has been assoc ...19957547110
the global distribution of lyme disease.erythema chronicum migrans (ecm), the skin lesion characteristic of lyme disease, was first described in sweden in 1909; subsequently, cases of ecm have been reported from at least 19 countries on three continents. in europe cases have occurred within the range of ixodes ricinus ticks, the recognized vector of ecm in europe, although one case outside this range has been ascribed to mosquito bites. in 1970 the first case of ecm acquired in the united states was reported, and in 1977, the full sym ...19853885366
clinical and serologic studies of canine borreliosis.during 1984 and 1985, blood samples were obtained from 271 dogs that were suspected of having borreliosis. the dogs lived in areas known to be infested with ticks and had been examined because of limb/joint disorders or for unknown illnesses marked by fever, anorexia, or fatigue. lameness had been the most frequently reported clinical manifestation. analyses of serum specimens, by an indirect fluorescent antibody (ifa) method or by an elisa, detected antibodies to borrelia burgdorferi, the etiol ...19873319989
lyme disease in california: interrelationship of ixodes pacificus (acari: ixodidae), the western fence lizard (sceloporus occidentalis), and borrelia burgdorferi.the relationship of immature western black-legged ticks, ixodes pacificus cooley and kohls, to the western fence lizard, sceloporus occidentalis baird and girard, and to the lyme disease spirochete, borrelia burgdorferi, was investigated in chaparral and woodland-grass habitats in northern california from 1984 to 1986. immature ticks were found on lizards in spring and summer, but the prevalence and abundance of ticks on this host were considerably greater in spring. the peak of larval abundance ...19892769705
lagomorphs as sentinels for surveillance of borreliosis in the far western united states.brush rabbits (sylvilagus bachmani) and black-tailed jackrabbits (lepus californicus) from california (usa) were assayed for antibodies to borrelia burgdorferi, the etiologic agent of lyme borreliosis. significant antibody titers were detected in 90% (range, 67 to 100%) of brush rabbits from four of six localities, and in 90% of jackrabbits from a single locality, in northern california. one of the populations of brush rabbits that did not yield seropositive individuals inhabited an oceanic isla ...19892716099
antigenic characteristics of borrelia burgdorferi isolates from ixodid ticks in california.twenty (1.4%) of 1,421 adult ixodes pacificus ticks and 2 (20%) of 10 adult ixodes neotomae ticks collected in five counties of northern california were found to contain spirochetes by direct immunofluorescence examination of their tissues with a polyvalent conjugate. borreliae isolated from the tissues of nine of these ticks (i. pacificus, 8; i. neotomae, 1) were identified as borrelia burgdorferi with specific monoclonal antibodies and characterized further by polyacrylamide gel electrophoresi ...19892685030
isolation of borrelia burgdorferi from the blood of a bushy-tailed wood rat in california.borrelia burgdorferi was isolated from the blood of a bushy-tailed wood rat (neotoma cinerea) from northeastern california, usa. this is the first isolation of live b. burgdorferi spirochetes from a wild animal in california. spirochetes were observed in stained tissues from the brain, liver, spleen, and kidneys.19938355352
first isolation of borrelia burgdorferi in southern california.the lyme disease spirochete, borrelia burgdorferi johnson, schmid, hyde, steigerwalt & brenner, was isolated from the blood of a dusky-footed wood rat, neotoma fuscipes baird, in the san bernardino mountains of southern california. antigenic, protein, and molecular analyses demonstrated that the isolate varied slightly from most isolates of b. burgdorferi from northern california and was clearly distinct from other species of borrelia that are endemic to the state. this is the first reported iso ...19921625299
lyme disease in california: a novel enzootic transmission cycle of borrelia burgdorferi.knowledge of zoonotic transmission cycles is essential for the development of effective strategies for disease prevention. the enzootiology of lyme disease in california differs fundamentally from that reported from the eastern united states. woodrats, not mice, serve as reservoir hosts, and ixodes neotomae, a nonhuman-biting tick, maintains the agent of lyme disease, borrelia burgdorferi, in enzootic cycles. the western black-legged tick, ixodes pacificus, is the primary vector to humans, but i ...19921604318
isolation of borrelia burgdorferi from ticks in southern california. 19921462548
cases of lyme disease in the united states: locations correlated with distribution of ixodes dammini.lyme disease, defined by erythema chronicum migrans and sometimes followed by neurologic, cardiac, or joint involvement, is known to have affected 512 patients in the united states. the disease seems to occur in three distinct foci: along the northeastern coast, in wisconsin, and in california and oregon, a distribution that correlates closely with that of ixodes dammini in the first two areas and with ixodes pacificus in the last. the implicated tick, saved by six patients in the northeast, was ...1979496106
genetic diversity among borrelia burgdorferi isolates from wood rats and kangaroo rats in california.twenty-nine borrelia burgdorferi isolates, obtained from dusky-footed wood rats (neotoma fuscipes) and california kangaroo rats (dipodomys californicus) in california, were analyzed genetically. chromosomal dna was examined by restriction endonuclease analysis (rea) and gene probe restriction fragment length polymorphism. pulsed-field gel electrophoresis was used to analyze the plasmid profiles of the isolates. rea, the method with the greatest discrimination, disclosed 24 distinct restriction p ...19937905880
lyme disease: additional evidence of widespread distribution. recognition of a tick-borne dermatitis-encephalitis-arthritis syndrome in an area of known ixodes tick distribution.lyme disease is a process of unknown etiology that has been linked to bites of ticks of the ixodes ricinus complex. central minnesota is an area of known ixodes dammini distribution. this case represents the first recognition of lyme disease from this area. this case presented as a fluctuating meningoencephalitis with superimposed cranial neuropathy. the characteristic skin lesion, erythema chronicum migrans, was recognized by history, and oligoarticular arthritis subsequently developed. physici ...19827072749
characterization of borrelia burgdorferi strains isolated from ixodes pacificus ticks in a survey of 1,714 adult ixodes pacificus ticks collected in northern california, 24 (1.4%) were found to be infected with spirochetes that reacted with an anti-borrelia burgdorferi polyvalent conjugate in direct immunofluorescence tests. eleven isolates of b. burgdorferi from these ticks were characterized by monoclonal antibody, polyacrylamide gel electrophoresis, and western blot (immunoblot) analyses. ten of the isolates had molecular and antigenic characteristics similar to those of other ...19873323225
interlaboratory and intralaboratory comparisons of indirect immunofluorescence assays for serodiagnosis of lyme disease.a conventional indirect immunofluorescence assay (ifa) and an anticomplement indirect immunofluorescence assay (acif) for detecting serum antibodies to borrelia burgdorferi in humans were evaluated during a prevalence survey in northern california. sera obtained from 119 current or former residents of an area in which lyme disease is endemic were split and tested by the ifa in two laboratories and the acif in a third. the seropositivity rate ranged from 15 to 20% with 88 to 93% agreement among l ...19902203813
wood rats and kangaroo rats: potential reservoirs of the lyme disease spirochete in california.the etiologic agent of lyme disease, borrelia burgdorferi johnson, schmid, hyde, steigerwalt & brenner, was isolated repeatedly from dusky-footed wood rats, neotoma fuscipes baird, and california kangaroo rats, dipodomys californicus merriam, in northern california. all animals were collected in a region endemic for lyme disease but for which the natural reservoir of b. burgdorferi was unknown. similar attempts to isolate spirochetes from lizards, other species of rodents, jack rabbits, and deer ...19911875357
the western black-legged tick, ixodes pacificus: a vector of borrelia 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 sp ...19853898886
the use of serologic tests for lyme disease in a prepaid health plan in determine the reason(s) why serologic tests for lyme disease are performed, who initiates the test requests, and how the test results are used in a clinical setting.19948080498
the western fence lizard sceloporus occidentalis: evidence of field exposure to borrelia burgdorferi in relation to infestation by ixodes pacificus (acari: ixodidae).the role of the western fence lizard sceloporus occidentalis in the enzootiology of the lyme disease spirochete borrelia burgdorferi was evaluated in the hopland and ukiah areas of mendocino county, california. in 1989, half of 74 lizards collected monthly from april to october at hopland were infested by the immature western black-legged tick ixodes pacificus at a mean intensity of 6.0 ticks per lizard. the prevalence of infestation of lizards by immature i. pacificus (36 of 73) at ukiah was si ...19921524146
dna and protein analyses of tick-derived isolates of borrelia burgdorferi from california.nine isolates of borrelia burgdorferi from ixodid ticks collected in northern california were characterized. restriction endonuclease analysis, pulsed-field gel electrophoresis, and western blot (immunoblot) analysis were used in this study. four isolates were very similar to each other. the others shared some similarities but were classified as having unique genotypes. a strain from an ixodes neotomae tick displayed the greatest genetic and antigenic diversity when compared to the isolates coll ...19902332468
survey of birds and lizards for ixodid ticks (acari) and spirochetal infection in northern california.a total of 138 birds (24 species) was captured in an oak woodland between december 1988 and june 1989 at the university of california, sierra foothill range field station, yuba county, calif. ticks were not found on 71 birds captured between december 1988 and march 1989. five subadult ixodes pacificus cooley & kohls were removed from 3 of 67 birds caught between april and june 1989. these three birds, an orange-crowned warbler (vermivora celata (say], a lazuli bunting (passerina amoena (say], an ...19902280384
genotypic and phenotypic characterization of borrelia burgdorferi isolated from ticks and small animals in illinois.we have characterized 33 isolates of borrelia burgdorferi from northern illinois (32 isolates) and wisconsin (1 isolate) representing the largest series of midwestern isolates investigated to date. the techniques used for molecular analysis of strains included (i) genospecies typing with species-specific pcr primers, (ii) plasmid profiling by pulsed-field gel electrophoresis of total genomic dna, (iii) large-restriction-fragment pattern (lrfp) analysis by pulsed-field gel electrophoresis of mlui ...19957494019
evidence implicating nymphal ixodes pacificus (acari: ixodidae) in the epidemiology of lyme disease in clarify the role of nymphal versus adult western black-legged ticks (ixodes pacificus) in the epidemiology of lyme disease, the seasonal distribution, abundance, and spirochetal infection rates in these stages, and the seasonal occurrence of ticks biting humans and of incident cases of lyme disease were determined in northern california. although their seasonal activity periods overlapped for about one-third of the year, nymphs and adults predominated in different seasons, the former from lat ...19957573703
ixodes (ixodes) jellisoni and i. (i.) neotomae (acari:ixodidae): descriptions of the immature stages from california.nymphal and larval stages of ixodes (ixodes) jellisoni cooley & kohls and i. (i.) neotomae cooley are described for the first time. these 2 tick species occur only in the western united states, predominantly in california. the primary host for i. jellisoni is the california kangaroo rat, dipodomys californicus (merriam); that for i. neotomae is the dusky-footed woodrat, neotoma fuscipes baird. the etiologic agent of lyme disease borrelia burgdorferi johnson, schmidt, hyde, steigerwalt & brenner ...19968667376
evaluation of permethrin-impregnated cotton balls as potential nesting material to control ectoparasites of woodrats in california.the dusky-footed woodrat, neotoma fuscipes baird is a natural reservoir of the lyme disease spirochete, borrelia burgdorferi johnson, schmid, hyde, steigerwalt & brenner, in california. to investigate the potential of host-targeted insecticide to control the tick vectors of b. burgdorferi, permethrin-impregnated or untreated cotton balls were distributed in metal cylinders as potential nesting material adjacent to 95 woodrat houses in chaparral-covered rangeland. laboratory experiments demonstra ...19968667381
comparison of infectivities of six tick-derived isolates of borrelia burgdorferi for rodents and ticks.the infectivity and dissemination to the skin of six isolates of borrelia burgdorferi were evaluated by inoculating them into groups of deer mice (peromyscus maniculatus), hamsters, and swiss webster mice. rodent infection was assayed by culture of ear punch biopsy specimens taken at 4, 8, and 12 weeks postinoculation (p.i.). spirochetes were detected in biopsy specimens from individuals of all three host species that had been inoculated with four isolates (ca3, ca4, ca7, and ca8). ear punch bio ...19968748276
natural and experimental borrelia burgdorferi infections in woodrats and deer mice from california.sequestration of spirochetes and concurrent histopathologic lesions were evaluated in tissues of borrelia burgdorferi-infected dusky-footed woodrats (neotoma fuscipes) and deer mice (peromyscus maniculatus). rodents were either wild-caught and naturally infected or were experimentally infected by tick bite, by intramuscular (i.m.) injection of cultured spirochetes, or by i.m. injection of tick suspensions. samples of host tissues, including skin, blood, ear, brain, eye, heart, lung, liver, splee ...19947933283
detection of the agents of human ehrlichioses in ixodid ticks from california.a study was conducted in northern california to estimate the prevalence and distribution in ixodid ticks of the rickettsial agents of human monocytic (hme) and human granulocytic (hge) ehrlichioses. more than 650 ixodid ticks were collected from 17 sites in six california counties over a 15-month period. ehrlichia chaffeensis, the causative agent of hme, was detected by a nested polymerase chain reaction (pcr) in ixodes pacificus (minimum infection rate [mir] = 13.3%) and dermacentor variabilis ...19999988324
evaluation of host preferences by helminths and ectoparasites among black-tailed jackrabbits in northern california.fifty-four black-tailed jackrabbits (lepus californicus) (five juvenile males, 22 adult males, five juvenile females, and 22 adult females) from humboldt county, california (usa) were evaluated for sex and age-specific differences in parasite prevalences and intensities, 26 february through 30 october 1996. nematodes found included biogastranema leporis in 42 hares (78% prevalence), rauschia triangularis in 26 hares (48%), trichostrongylus calcaratus in 14 hares (26%), and trichuris sylvilagi in ...200010941744
risk of human exposure to vector ticks (acari: ixodidae) in a heavily used recreational area in northern california.the risk of humans encountering vector ticks along hiking trails or in picnic grounds in a lyme disease-endemic area was evaluated in a multipurpose recreational area (tilden regional park) in the populous san francisco bay region of california. four hillside hiking trails (two high-use, two low-use) were sampled by dragging and walking through low vegetation biweekly for one year; four heavily used picnic areas were sampled concurrently by dragging. adults of three human-biting ticks were enume ...19968780455
serologic survey for selected infectious disease agents in swift and kit foxes from the western united states.a serologic survey of swift fox (vulpes velox) and kit fox (v. macrotis) from the western usa was conducted for 12 infectious diseases. samples from swift fox were collected between 1987 and 1992 from colorado (n = 44), kansas (n = 10), and wyoming (n = 9). samples from kit fox were collected in california (n = 86), new mexico (n = 18), utah (n = 9), and arizona (n = 6). overall antibody prevalence rates were 33 of 110 (30%) for canine parvovirus (cpv), 9 of 72 (13%) for canine distemper virus ( ...200011085448
risk factors for lyme disease in a small rural community in northern california.a 1-year prospective study of risk factors for seropositivity to and contraction of lyme disease among members of a small rural community (population, approximately 150) was conducted in northwestern california in 1988-1989. the initial rate of seropositivity for borrelia burgdorferi for 119 current or former residents ranged from 15 to 20% among three laboratories, with statistically significant interlaboratory agreement. questionnaires were completed by 93 current residents at entry and 80 res ...19921488962
spirochetes in mammals and ticks (acari: ixodidae) from a focus of lyme borreliosis in northern california, antibodies to borrelia burgdorferi were detected in 58 of 73 (79%), and spirochetemias in one of 26 (4%) black-tailed jackrabbits (lepus californicus californicus), by indirect and direct immunofluorescence, respectively. five species of ticks (dermacentor occidentalis, d. parumapertus, ixodes neotomae, i. pacificus, and haemaphysalis leporispalustris) were collected from rabbits. two of these species of ticks were found to contain spirochetes; two of 10 (20%) i. neotomae ...19883280837
potential role of native and exotic deer and their associated ticks (acari: ixodidae) in the ecology of lyme disease in california, usa.the relationship of native columbian black-tailed deer, two species of exotic deer (axis and fallow), and their ticks to the lyme disease spirochete, borrelia burgdorferi, was studied in coastal and inland areas of northern california, usa. spirochetemias were detected in 27% of black-tailed deer, 50% of axis deer, and 56% of fallow deer collected in late fall and winter. antibody prevalence was 38% in black-tailed deer, 24% in fallow deer, and 6% in axis deer. one to 3 tick species were collect ...19863554845
lyme borreliosis in california. acarological, clinical, and epidemiological studies.the relative abundance of, and spirochetal-infection rates in, adult ixodid ticks from eight lyme borreliosis clinical-case areas and two comparison areas were investigated in northern california from late fall to early spring, 1984-87. the western black-legged tick (ixodes pacificus) was the most abundant species at seven of nine sites yielding specimens as determined with a tick drag method. the pacific coast tick (dermacentor occidentalis) was the most abundant species at two sites, and lesse ...19883263826
role of small mammals in the ecology of borrelia burgdorferi in a peri-urban park in north coastal california.the role of small mammals other than woodrats in the enzootiology of the lyme disease spirochete, borrelia burgorferi, was assessed in the peri-urban park. mammals were collected monthly from september through to april. following tick removal, the animals were tested for b. burgdorferi by culture of ear-punch biopsies. larvae and nymphs that were intermediate in morphology between ixodes spinipalpis and ixodes neotomae occurred on several species of rodents (peromyscus truei, peromyscus californ ...19979291589
lyme disease in northwestern coastal determine the incidence of physician-diagnosed lyme disease in an endemic area of california, an active surveillance program was implemented in lake, mendocino, sonoma, and southern humboldt counties. more than 200 medical care providers were called monthly for their list of suspected cases of lyme disease. pertinent information was abstracted from the medical record of each patient. of 153 cases of possible early lyme disease ascertained from july 1991 to december 1992, 37% consisted of phys ...19948053175
temporal and spatial distribution of ixodes pacificus and dermacentor occidentalis (acari: ixodidae) and prevalence of borrelia burgdorferi in contra costa county, california.the seasonal activity and spatial distribution of adult and immature ixodes pacificus cooley & kohls and dermacentor occidentalis marx were determined along trails and on hillsides in two parks in contra costa county, ca. i. pacificus and d. occidentalis adults were most numerous in january and may, respectively. adult ticks were significantly more abundant along heavily vegetated trails than on open grassy hillsides, and on the uphill versus the downhill side of trails. five species of rodents ...19938510115
the western black-legged tick, ixodes pacificus, in the sutter buttes.the western black-legged tick, ixodes pacificus, was collected from huff canyon in the sutter buttes in north central california, sutter county. the sutter buttes are within the sacramento valley and outside the normal distribution of i. pacificus in california. adult i. pacificus were collected via flagging as they quested along deer trails; subadult life stages were collected from three species of lizard, elgaria multicarinata, sceloporus occidentalis, and s. graciosus. adult ticks were tested ...200314714665
variation in the density of questing ixodes pacificus (acari:ixodidae) nymphs infected with borrelia burgdorferi at different spatial scales in california.the density of, and prevalence of infection with borrelia burgdorferi in, ixodes pacificus nymphs as well as the density of infected nymphs were compared at 12 properties at a small rural community at high risk for lyme disease (chr) and at 12 areas at the university of california hopland research and extension center (hrec), mendocino county, california. the mean infection prevalence and density of infected nymphs were 1.7% (range, 0-4.2%) and 0.10 infected nymphs per 100 m2 (range, 0-0.23 per ...199910577716
compatibility of two species of ixodes ticks with murid hosts and its effect on transmission of lyme disease spirochaetes. 19968887343
lyme disease in california: interrelationship of ixodid ticks (acari), rodents, and borrelia burgdorferi.the association of immature ixodid ticks, several species of rodents, and the lyme disease spirochete, borrelia burgdorferi johnson, schmid, hyde, steigerwalt & brenner, was studied in two habitats in northern california in spring and summer 1985 and year-round in 1986. a total of 428 rodents were collected from ecotonal chaparral and a woodland-grass-rock outcrop; the former habitat yielded six species, the latter three species. the deer mouse, peromyscus maniculatus (wagner), and the piñon mou ...19911941942
distribution and molecular analysis of lyme disease spirochetes, borrelia burgdorferi, isolated from ticks throughout california.previous studies describing the occurrence and molecular characteristics of lyme disease spirochetes, borrelia burgdorferi, from california have been restricted primarily to isolates obtained from the north coastal region of this large and ecologically diverse state. our objective was to look for and examine b. burdorferi organisms isolated from ixodes pacificus ticks collected from numerous regions spanning most parts of california where this tick is found. thirty-one isolates of b. burgdorferi ...19938308101
nervous about ticks--assessing lyme disease risk in san diego county. 19921734618
failure to identify borrelia burgdorferi in southern california ticks by dna amplification. 19938515128
two geographically distinct isolates of borrelia burgdorferi from the united states share a common unique ancestor.the genetic diversity of borrelia burgdorferi isolates from several geographic regions was evaluated by nucleotide sequence analysis of the genes encoding 23s ribosomal rna and outer surface protein a. comparison of nucleotide sequences spanning 738 bp of the 23s ribosomal dna from two unusual isolates, dn127 (del norte county, california) and 25015 (millbrook, new york), to homologous sequences from other b. burgdorferi isolates from the united states and russia identified several nucleotide se ...19958525058
expanded diversity among californian borrelia isolates and description of borrelia bissettii sp. nov. (formerly borrelia group dn127).up to now, the only species in the complex borrelia burgdorferi sensu lato known to cause lyme borreliosis in the united states has been b. burgdorferi sensu stricto. however, some atypical strains closely related to the previously designated genomic group dn127 have been isolated in the united states, mostly in california. to explore the diversity of b. burgdorferi sensu lato group dn127, we analyzed the nucleotide sequences of the rrf-rrl intergenic spacer regions from 19 atypical strains (18 ...19989817861
population genetic structure of ixodes pacificus (acari:ixodidae) using allozymes.genetic analysis of the population structure of the western blacklegged tick, ixodes pacificus cooley & kohls, was conducted using allozymes. this vector tick transmits the lyme disease spirochete, borrelia burgdorferi johnson, schmid, hyde, steigerwalt & brenner, in the far-western united states. it ranges from british columbia to baja california and disjunct populations are present in oregon, nevada, utah, and arizona. host-seeking adult ticks were collected from vegetation across the range of ...19979220679
multivariate morphometric discrimination of nymphal and adult forms of the blacklegged tick (acari: ixodidae), a principal vector of the agent of lyme disease in eastern north america.a morphological study of postlarval stages of the blacklegged tick, ixodes scapularis say, was conducted to examine congruence between northern (formerly i. dammini spielman, clifford, piesman & corwin) and southern morphotypes. the character set totaled 17 for females, 25 for males, and 28 for nymphs. populations from 6 geographic areas, f1 progeny from reciprocal crosses between i. scapularis from massachusetts and georgia, and i. pacificus cooley & kohls from california were measured. charact ...19958551506
antibody prevalence of eight ruminant infectious diseases in california mule and black-tailed deer (odocoileus hemionus).we tested 276 sera from 18 free-ranging black-tailed and mule deer (odocoileus hemionus) herds in california (usa) collected from 1987 to 1991 in five biogeographical habitat types, for antibodies against eight infectious disease agents. overall antibody prevalence was 56% for anaplasma marginale, 31% for borrelia burgdorferi, 16% for bluetongue virus serotype 17, 15% for epizootic hemorrhagic disease virus, 7% for coxiella burnetii and toxoplasma gondii, respectively, and 0% for bovine leukosis ...19948151824
seroepidemiology of emerging tickborne infectious diseases in a northern california community.a seroprevalence and risk factor study of emerging tickborne infectious diseases (lyme disease, ehrlichiosis, and babesiosis) was conducted among 230 residents of a semirural community in sonoma county, california. over 50% of residents reported finding a tick on themselves in the preceding 12 months. samples from 51(23%) residents were seroreactive to antigens from one or more tickborne disease agents: 1.4% to borrelia burgdorferi, 0.4% to ehrlichia equi, 4.6% to ehrlichia chaffeensis, and 17.8 ...19979180183
vector competence of ixodes angustus (acari: ixodidae) for borrelia burgdorferi sensu stricto.the vector competence of ixodes angustus for borrelia burgdorferi sensu stricto (s.s.) was investigated in the laboratory. the larval progeny of female ticks from washington state were placed on swiss-webster mice that had been inoculated intravenously with 10(8) spirochetes each of a californian isolate of b. burgdorferi. spirochetes were detected in 6 (12%) of 50 nymphs derived from larvae that had fed on these animals. ten nymphs from the same cohort of experimentally infected ticks were plac ...200010823359
population genetics and phylogenetic analysis of colorado borrelia burgdorferi.borrelia burgdorferi is transmitted in an enzootic cycle in colorado between the tick ixodes spinipalpis and the woodrat neotoma mexicana. the genetic relationship of colorado isolates to other b. burgdorferi isolates is unknown nor have relationships among various colorado isolates been determined. portions of the flagellin (fla), 66-kd protein, and outer surface protein a (ospa) genes were amplified from 71 colorado isolates, screened for genetic variability using single strand conformation po ...199910348251
ecology of borrelia burgdorferi in ticks (acari: ixodidae), rodents, and birds in the sierra nevada foothills, placer county, california.this study examined the prevalence of borrelia burgdorferi johnson, schmid, hyde, steigerwalt & brenner in host-seeking adult and nymphal ixodes pacificus cooley & kohls and estimated the i. pacificus infestation and b. burgdorferi infection of rodent and avian hosts in the western sierra nevada foothills of northern california. additionally, we identified species likely to participate in an enzootic cycle for b. burgdorferi in this yellow pine transition habitat. evidence of infection with b. b ...200011126549
acarologic risk of exposure to emerging tick-borne bacterial pathogens in a semirural community in northern acarologic study was conducted in a semirural community in northern california to determine the relative abundance of, and the prevalence of infection with, three emerging bacterial pathogens in the western black-legged tick (ixodes pacificus). these included the agents causing lyme disease (borrelia burgdorferi), human granulocytic ehrlichiosis [ehrlichia phagocytophila (formerly ehrlichia equi)], and human monocytic ehrlichiosis (ehrlichia chaffeensis). the study area in sonoma county consi ...200112653148
reservoir competence of four chaparral-dwelling rodents for borrelia burgdorferi in california.aspects of the reservoir competence of four rodents for the lyme disease spirochete, borrelia burgdorferi, were evaluated in california. rodents were live-trapped and ear-punch biopsies were cultured during each season. a second set of biopsies was cultured from representative individuals after 2-3 weeks of captivity and the results of culturing biopsies taken on both dates were compared with the results of feeding ixodes pacificus larvae on hosts xenodiagnostically. the prevalence of infections ...19968651378
ecology of anaplasma phagocytophilum and borrelia burgdorferi in the western united states.we discuss the ecology of anaplasma phagocytophilum and borrelia burgdorferi in the western u.s. these agents, while emerging in the eastern u.s., remain stable or rare in the west. in the western u.s., tick vectors and mammalian hosts for b. burgdorferi and a. phagocytophilum are distinct from those in the eastern u.s. and considerably more variable. spatial complexity, local extinctions, and low levels of movement among foci may determine the distribution and prevalence of these agents. high-p ...200415266739
abundance of ticks (acari: ixodidae) infesting the western fence lizard, sceloporus occidentalis, in relation to environmental factors.we examined the impact of environmental characteristics, such as habitat type, topographic exposure and presence of leaf litter, on the abundance of ixodes pacificus ticks infesting the western fence lizard (sceloporus occidentalis) at the university of california hopland research and extension center (hrec), mendocino county, california. a total of 383 adult lizards were slip-noosed and examined for tick infestation in april and may 1998. at least 94% of the lizards were infested by ticks and a ...199910581712
association between polyarthritis and thrombocytopenia and increased prevalence of vectorborne pathogens in californian dogs. 200717277299
persistent infection in neotoma fuscipes (muridae: sigmodontinae) with ehrlichia phagocytophila sensu lato.dusky-footed wood rats (neotoma fuscipes baird) and two species of peromyscus mice (p. maniculatus wagner and p. truei shufeldt) were collected over a 16-month period from three sites in sonoma county, california. blood was collected from 93 wood rats and 177 mice and serum or plasma was tested for seroreactivity with ehrlichia phagocytophila sensu lato (also known as the human granulocytic ehrlichiosis agent). thirty-five (37.6%) wood rats and 15 (8.5%) mice were seropositive. positive neotoma ...200111693866
density and spatial distribution of ixodes pacificus (acari: ixodidae) in two recreational areas in north coastal california.the density and distribution of ixodes pacificus was assessed at 2 parks in north coastal california. the density of i. pacificus adults and nymphs varied significantly between years, trails, and sides of trails. adult ticks occurred on vegetation along sun-exposed trails in january through march, their density (0-1.93 per 20 m) correlated with brush density, trail width, and presence of an uphill slope. nymphs (0.06-5.10 per 20 m) occurred in leaf litter along shaded trails in may-july. adult i ...200011037789
molecular evidence of bartonella spp. in questing adult ixodes pacificus ticks in california.ticks are the vectors of many zoonotic diseases in the united states, including lyme disease, human monocytic and granulocytic ehrlichioses, and rocky mountain spotted fever. most known bartonella species are arthropod borne. therefore, it is important to determine if some bartonella species, which are emerging pathogens, could be carried or transmitted by ticks. in this study, adult ixodes pacificus ticks were collected by flagging vegetation in three sites in santa clara county, calif. pcr-res ...200111283031
birds and their ticks in northwestern california: minimal contribution to borrelia burgdorferi enzootiology.birds and their attendant ticks were surveyed for infection with the lyme disease spirochete borrelia burgdorferi, in chaparral and woodland-grass habitats in northwestern california from march to july, 1998 to 1999. in total, 234 birds were captured and recaptured (15%); nearly 2.5 times more birds were captured in chaparral than in woodland-grass. overall, 34 species representing 15 families were collected during this study; of these, 24 species were caught in chaparral, 19 in woodland-grass, ...200111534638
detection of borrelia burgdorferi, ehrlichia chaffeensis, and anaplasma phagocytophilum in ticks (acari: ixodidae) from a coastal region of california.a study was conducted in santa cruz county to estimate the prevalence and distribution of the agents of lyme disease, human granulocytic (hge), and human monocytic (hme) ehrlichiosis in 1,187 adult ixodid ticks collected from eight public-use recreation areas over a 2-yr period. borrelia burgdorferi, the causative agent of lyme disease, was detected by a polymerase chain reaction (pcr) in 44 of 776 (5.67%) ixodes pacificus ticks and in 3 of 58 (5.17%) dermacentor variabilis ticks. anaplasma phag ...200314680123
prevalence and abundance of ixodes pacificus immatures (acari: ixodidae) infesting western fence lizards (sceloporus occidentalis) in northern california: temporal trends and environmental correlates.the prevalence and abundance of immature ixodes pacificus ticks on western fence lizards (sceloporus occidentalis) were examined in relation to time of year, host attributes (i.e., age, gender, and presence or absence of blood parasites), and 5 environmental characteristics, including topographic exposure and ground cover substrate, over a 2-year period in northern california. lizards were infested with subadult ticks from early march until late july or early august, with peak median numbers of ...200111780813
habitat-related variation in infestation of lizards and rodents with ixodes ticks in dense woodlands in mendocino county, california.during the spring and early summer of 2002, we examined the relative importance of borrelia-refractory lizards (sceloporus occidentalis, elgaria spp.) versus potential borrelia burgdorferi sensu lato (s.l.)-reservoirs (rodents) as hosts for ixodes pacificus immatures in 14 woodland areas (six oak, five mixed oak/douglas fir, and three redwood/tanoak areas) distributed throughout mendocino county, california. lizards were estimated to serve as hosts for 93-98% of all larvae and > or =99.6% of all ...200415347025
detection and characterization of borrelia bissettii in rodents from the central california coast.this is the first report of borrelia burgdorferi sensu lato in rodents from san luis obispo county, with most isolates obtained from a previously unreported host, neotoma lepida thomas. b. burgdorferi sensu lato was identified in seven rodent species, including the california vole, microtus californicus peale; dusky-footed woodrat, neotoma fuscipes baird; desert woodrat, neotoma lepida thomas; brush mouse, peromyscus boylii baird; california mouse, peromyscus californicus gambel; deer mouse, per ...200415311469
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).the primary aims of this study were to quantify the density of ixodes pacificus cooley and kohls nymphs and adults of the same generational cohort collected within a single year in six oak or madrone leaf litter habitats and to compare the prevalence of infection with borrelia burgdorferi sensu lato (s.l.) in adults originating from nymphal cohorts with a low (<1%) versus high (>10%) infection prevalence. because adult densities were very low both in and adjacent to several sites, direct compari ...200415311473
anti-arthropod saliva antibodies among residents of a community at high risk for lyme disease in california.the role of the western black-legged tick (ixodes pacificus) versus that of other potential arthropod vectors in the epidemiology of lyme disease was evaluated by determining the prevalence of anti-arthropod saliva antibodies (aasa) among residents (n = 104) of a community at high-risk (chr). salivary gland extracts prepared from i. pacificus, the pacific coast tick (dermacentor occidentalis), the western cone-nose bug (triatoma protracta), and the western tree-hole mosquito (aedes sierrensis) w ...199910586924
human behaviors elevating exposure to ixodes pacificus (acari: ixodidae) nymphs and their associated bacterial zoonotic agents in a hardwood forest.epidemiological evidence suggests that the nymph of the western black-legged tick, ixodes pacificus cooley and kohls, is the primary vector of the lyme disease spirochete, borrelia burgdorferi johnson, schmid, hyde, steigerwalt, and brenner, to humans in northwestern california. in spring 2002, six different human behaviors were evaluated as potential risk factors for acquiring i. pacificus nymphs in a deciduous woodland in mendocino county, california. also, the prevalence of b. burgdorferi sen ...200415061284
canines as sentinels for lyme disease in san diego county, california.prevalence of lyme borreliosis in canine sentinels has been shown to correlate with infection in humans. one thousand canine sera (917 dogs, 83 coyotes) obtained from animal control authorities and area veterinarians were screened by elisa for antibodies to borrelia burgdorferi. results were validated by western blot and indirect fluorescent antibody (ifa) tests at referee laboratories. criterion for a positive western blot was presence of 5 of 10 of the most common antigen igg bands; for ifa, > ...200010730940
mitochondrial dna sequence variation in ixodes pacificus (acari: ixodidae).the western black-legged tick, ixodes pacificus, is a primary vector of the spirochaete, borrelia burgdorferi, that causes lyme disease. we used variation in a 355-bp dna portion of the mitochondrial cytochrome oxidase iii gene to assess the population structure of the tick across its range from british columbia to southern california and east to utah. ixodes pacificus showed considerable haplotype diversity despite low nucleotide diversity. maximum parsimony and isolation-by-distance analyses r ...199910583539
columbian black-tailed deer (odocoileus hemionus columbianus) as hosts for borrelia spp. in northern california.the prevalence of infection of columbian black-tailed deer (odocoileus hemionus columbianus) with borrelia spp. was evaluated in an area of northwestern california (usa) where lyme disease is endemic and the relapsing-fever group spirochete borrelia coriaceae is enzootic, and in a far-removed comparison area having a disparate climate and lower density of vector ticks. blood samples collected from both deer herds in 1987, 1988, and from 2000-02 were assayed for borrelial infection with microscop ...200515827217
remote sensing (normalized difference vegetation index) classification of risk versus minimal risk habitats for human exposure to ixodes pacificus (acari: ixodidae) nymphs in mendocino county, california, ixodes pacificus cooley & kohls nymphs have been implicated as the primary bridging vectors to humans of the spirochetal bacterium causing lyme disease (borrelia burgdorferi). because the nymphs typically do not ascend emergent vegetation, risk of human exposure is minimal in grasslands, chaparral, and woodland-grass. instead, woodlands with a ground cover dominated by leaf litter (hereinafter referred to as woodland-leaf) have emerged as a primary risk habitat for exposure to b. ...200515691012
the roles of birds, lizards, and rodents as hosts for the western black-legged tick ixodes pacificus.we compared the infestation by ixodid ticks of lizards, rodents, and birds collected simultaneously within areas representing common habitat types in mendocino county, ca. lizards were infested only by ixodes pacificus cooley and kohls, birds by i. pacificus and haemaphysalis leporispalustris (packard), and rodents by i. pacificus, i. spinipalpis hadwen and nuttall, i. woodi bishopp, dermacentor occidentalis marx, and d. variabilis (say). infestation by i. pacificus larvae and nymphs of lizards ...200415709249
acarologic risk of exposure to borrelia burgdorferi spirochaetes: long-term evaluations in north-western california, with implications for lyme borreliosis risk-assessment models.over a 5-year period (1997-2001) the population densities of ixodes pacificus cooley & kohls (acari: ixodidae) nymphs infected with spirochaetes of borrelia burgdorferi sensu lato (s.l.) were evaluated in areas of 2000 ha at two localities (chr, nine sites; hrec, seven sites) 25 km apart in mendocino county, north-western california. the 5-year median density of infected nymphs was significantly higher at chr than at hrec (0.51 vs. 0.09 per 100 m(2) and site-specific yearly densities exceeding o ...200415009444
western gray squirrel (rodentia: sciuridae): a primary reservoir host of borrelia burgdorferi in californian oak woodlands?in california, dense woodlands have been recognized as important biotopes where humans are exposed to the nymphal stage of the western blacklegged tick, ixodes pacificus cooley & kohls, the primary vector of the lyme disease spirochete borrelia burgdorferi sensu stricto (s.s.), in the far-western united states. to identify the principal reservoir host(s) of this spirochete, and of closely related spirochetes in the b. burgdorferi sensu lato (s.l.) complex, in dense woodlands in mendocino county, ...200515962792
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.ixodes pacificus nymphs are the primary vectors to humans of borrelia burgdorferi, the etiologic agent of lyme disease, in california. we used a supervised classification model, based on remote sensing (rs) data from multi-seasonal landsat tm 5 images, to identify the key habitat in mendocino county where humans are exposed to i. pacificus nymphs (woodlands carpeted with leaf litter). the model, based on the normalized difference vegetation index (ndvi), brightness, and wetness, separated the ny ...200616606998
spatial analysis of the exposure of dogs in rural north-coastal california to vectorborne pathogens.between 0 and 50 per cent of the dogs in eight rural villages in far northern california with a high risk of tickborne diseases were seropositive for anaplasma phagocytophilum and bartonella vinsonii subspecies berkhoffii, and between 0 and 10 per cent were seropositive for borrelia burgdorferi. the odds ratio for the co-exposure of individual dogs to b vinsonii berkhoffii and a phagocytophilum was 18.2. none of the diseases was associated with the sex of the dogs, whether they slept out of door ...200717993656
spatial patterns of lyme disease risk in california based on disease incidence data and modeling of vector-tick exposure.ixodes pacificus, particularly the nymphal life stage, is the primary vector to humans of the lyme disease agent borrelia burgdorferi in california. during 2004, we collected i. pacificus 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 degrees c base). using a geographic information systems approach, w ...200617038692
gis-facilitated spatial epidemiology of tick-borne diseases in coyotes (canis latrans) in northern and coastal california.ixodes pacificus is the main tick vector for transmission of anaplasma phagocytophilum and borrelia burgdorferi to large vertebrates in california. the present study was undertaken in i. pacificus-infested counties in california to examine spatial and temporal relationships among a. phagocytophilum and b. burgdorferi-exposed coyotes with vegetation type and climate. the overall a. phagocytophilum and b. burgdorferi seroprevalences were 39.5% (n=215) and 18.9% (n=148), respectively, with no assoc ...200515857659
horizontal and vertical movements of host-seeking ixodes pacificus (acari: ixodidae) nymphs in a hardwood forest.the nymph of the western black-legged tick (ixodes pacificus) is an important bridging vector of the lyme disease spirochete (borrelia burgdorferi) to humans in the far-western united states. the previously unknown dispersal capabilities of this life stage were studied in relation to logs, tree trunks, and adjacent leaf-litter areas in a mixed hardwood forest using mark-release-recapture methods. in two spatially and temporally well-spaced trials involving logs, the estimated mean distances that ...200920352083
transmission cycles of borrelia burgdorferi and b. bissettii in relation to habitat type in northwestern california.this study was undertaken to determine which rodent species serve as primary reservoirs for the lyme disease spirochete borrelia burgdorferi in commonly occurring woodland types in inland areas of northwestern california, and to examine whether chaparral or grassland serve as source habitats for dispersal of b. burgdorferi- or b. bissettii-infected rodents into adjacent woodlands. the western gray squirrel (sciurus griseus) was commonly infected with b. burgdorferi in oak woodlands, whereas exam ...200920514140
sylvatic maintenance of borrelia burgdorferi (spirochaetales) in northern california: untangling the web of transmission.lyme borreliosis is associated with several genospecies of borrelia burgdorferi sensu lato (s.l.) (spirochaetales), but human disease has been associated only with borrelia burgdorferi sensu stricto (s.s.) johnson, schmid, hyde, steigerwalt & brenner in the western united states. restriction fragment length polymorphism (rflp) analysis of rrf-rrl amplicons from 124 tick and mammalian isolates from various habitats yielded 13 rflp patterns. of these patterns, six were patterns previously associat ...200616892634
co-detection of bartonella henselae, borrelia burgdorferi, and anaplasma phagocytophilum in ixodes pacificus ticks from california, usa.presence of bartonella dna was explored in 168 questing adult ixodes pacificus ticks from santa cruz county, california. bartonella henselae type i dna was amplified from 11 ticks (6.55%); previously, two (1.19%) were found to be infected with borrelia burgdorferi and five (2.98%) with anaplasma phagocytophilum. detection of b. henselae was not dependent on co-infection. the present study offers additional evidence that ixodes spp. ticks may act as hosts and possibly vectors for b. henselae.200616584332
wild turkey (meleagris gallopavo) as a host of ixodid ticks, lice, and lyme disease spirochetes (borrelia burgdorferi sensu lato) in california state grande wild turkeys (meleagris gallopavo intermedia) were evaluated as potential hosts of ixodid ticks, lice, and lyme disease spirochetes (borrelia burgdorferi sensu lato [s.l.]) in three state parks in sonoma county, california, usa, during 2003 and 2004. in total, 113 birds were collected, 50 (44.2%) of which were found to be infested by 361 ixodid ticks representing three species: the western black-legged tick (ixodes pacificus, n=248), the rabbit tick (haemaphysalis leporispalustris, n= ...200617255442
detection of a borrelia miyamotoi sensu lato relapsing-fever group spirochete from ixodes pacificus in california.we investigated whether host-seeking nymphs and adults of the western blacklegged tick, ixodes pacificus cooley & kohls, the primary vector of lyme disease spirochetes in far-western north america, are infected naturally with relapsing-fever group spirochetes in mendocino county, california. relapsing-fever group borreliae were detected in four (1.7%) of 234 nymphal and two (0.7%) of 282 adult host-seeking i. pacificus ticks by polymerase chain reaction and sequence analysis of the 16s rrna and ...200616506458
delineation of a new species of the borrelia burgdorferi sensu lato complex, borrelia americana sp. nov.analysis of borrelia isolates collected from ticks, birds, and rodents from the southeastern united states revealed the presence of well-established populations of borrelia burgdorferi sensu stricto, borrelia bissettii, borrelia carolinensis, and borrelia sp. nov. multilocus sequence analysis of five genomic loci from seven samples representing borrelia sp. nov. isolated from nymphal ixodes minor collected in south carolina showed their close relatedness to california strains known as genomospec ...200919846628
evolution and distribution of the ospc gene, a transferable serotype determinant of borrelia burgdorferi.borrelia burgdorferi, an emerging bacterial pathogen, is maintained in nature by transmission from one vertebrate host to another by ticks. one of the few antigens against which mammals develop protective immunity is the highly polymorphic ospc protein, encoded by the ospc gene on the cp26 plasmid. intragenic recombination among ospc genes is known, but the extent to which recombination extended beyond the ospc locus itself is undefined. we accessed and supplemented collections of dna sequences ...201020877579
effects of an invasive forest pathogen on abundance of ticks and their vertebrate hosts in a california lyme disease focus.invasive species, including pathogens, can have important effects on local ecosystems, including indirect consequences on native species. this study focuses on the effects of an invasive plant pathogen on a vertebrate community and ixodes pacificus, the vector of the lyme disease pathogen (borrelia burgdorferi) in california. phytophthora ramorum, the causative agent of sudden oak death, is a non-native pathogen killing trees in california and oregon. we conducted a multi-year study using a grad ...201020941513
population structure of the lyme borreliosis spirochete borrelia burgdorferi in the western black-legged tick (ixodes pacificus) in northern california.factors potentially contributing to the lower incidence of lyme borreliosis (lb) in the far-western than in the northeastern united states include tick host-seeking behavior resulting in fewer human tick encounters, lower densities of borrelia burgdorferi-infected vector ticks in peridomestic environments, and genetic variation among b. burgdorferi spirochetes to which humans are exposed. we determined the population structure of b. burgdorferi in over 200 infected nymphs of the primary bridging ...200919783741
coinfection of western gray squirrel (sciurus griseus) and other sciurid rodents with borrelia burgdorferi sensu stricto and anaplasma phagocytophilum in california.overlapping geographic distributions of tick-borne disease agents utilizing the same tick vectors are common, and coinfection of humans, domestic animals, wildlife, and ticks with both borrelia burgdorferi and anaplasma phagocytophilum has been frequently reported. this study was undertaken in order to evaluate the prevalence of both b. burgdorferi sensu stricto (hereinafter referred to as b. burgdorferi) and a. phagocytophilum in several species of sciurid rodents from northern california, usa. ...201020090047
ectoparasite diversity and exposure to vector-borne disease agents in wild rodents in central coastal california.a survey of wild rodents was performed in the morro bay area of central coastal california to determine serological and polymerase chain reaction (pcr) prevalence of anaplasma phagocytophilum dumler, barbet, bekker, dasch, palmer, ray, rikihisa, and rurangirwa, borrelia burgdorferi johnson, schmidt, hyde, steigerwalt, and brenner, francisella tularensis mccoy, and yersinia pestis yersin; to describe the ectoparasitic fauna on important vector-borne disease hosts; and to determine whether pathoge ...200717427705
effect of prescribed fire for tick control in california chaparral.prescribed fire was investigated as a method for controlling ixodid and argasid ticks in chaparral habitats in northern california. two experimental and two adjacent control plots within a wildlife preserve were monitored for 1 yr postburn. ticks were collected by flagging vegetation, by co2-baited pitfall trap, and by live-trapping rodents. twice as many rodents were caught at control sites compared with burn sites and no dusky-footed woodrats, neotoma fuscipes baird, were found in the treatmen ...200919769046
host, habitat and climate preferences of ixodes angustus (acari: ixodidae) and infection with borrelia burgdorferi and anaplasma phagocytophilum in california, usa.the holarctic tick ixodes angustus is a competent vector for borrelia burgdorferi, the etiologic agent of lyme disease, and possibly anaplasma phagocytophilum, the etiologic agent of granulocytic anaplasmosis, as well. from 2005 to 2013, we collected host-feeding i. angustus individuals from live-trapped small mammals and by flagging vegetation from 12 study sites in northern and central california, and tested for b. burgdorferi sensu lato, a. phagocytophilum, and rickettsia spp. dna by real-tim ...201627416728
demographic characteristics and infectious diseases of a population of american black bears in humboldt county, california.american black bears (ursus americanus) are common, widely distributed, and broad-ranging omnivorous mammals in northern california forests. bears may be susceptible to pathogens infecting both domestic animals and humans. monitoring bear populations, particularly in changing ecosystems, is important to understanding ecological features that could affect bear population health and influence the likelihood that bears may cause adverse impacts on humans. in all, 321 bears were captured between may ...201525700042
pathogen infection and exposure, and ectoparasites of the federally endangered amargosa vole (microtus californicus scirpensis), california, usa.abstract we surveyed pathogens and ectoparasites among federally endangered amargosa voles (microtus californicus scirpensis) and sympatric rodents in tecopa hot springs, inyo county, california, december 2011-november 2012. we aimed to assess disease and detect possible spillover from or connectivity with other hosts within and outside the amargosa ecosystem. we assessed 71 individual voles and 38 individual sympatric rodents for current infection with seven vector-borne zoonotic pathogens and ...201425121407
two boundaries separate borrelia burgdorferi populations in north america.understanding the spread of infectious diseases is crucial for implementing effective control measures. for this, it is important to obtain information on the contemporary population structure of a disease agent and to infer the evolutionary processes that may have shaped it. here, we investigate on a continental scale the population structure of borrelia burgdorferi, the causative agent of lyme borreliosis (lb), a tick-borne disease, in north america. we test the hypothesis that the observed po ...201222729536
influence of abiotic and environmental factors on the density and infection prevalence of ixodes pacificus (acari:ixodidae) with borrelia burgdorferi.the abiotic and biotic factors that govern the spatial distribution of lyme disease vectors are poorly understood. this study addressed the influence of abiotic and biotic environmental variables on ixodes pacificus cooley & kohls (acari:ixodidae) nymphs, because it is the primary vector of borrelia burgdorferi johnson, schmidt, hyde, steigerwaldt & brenner in the far-western united states. three metrics of lyme disease risk were evaluated: the density of nymphs, the density of infected nymphs, ...201121337944
arthropod vectors and vector-borne bacterial pathogens in yosemite national park.ticks, fleas, and vector-borne pathogens were surveyed in diverse small mammals in yosemite national park, california, from 2005 to 2007. a total of 450 unique captures of small mammals was collected during a 3-yr period and yielded 16 species of fleas and 10 species of ticks, including known vectors of anaplasma phagocytophilum and borrelia burgdorferi and plague. serology was performed for a. phagocytophilum, spotted fever group rickettsia spp., b. burgdorferi, and yersinia pestis. a. phagocyt ...201121337955
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