Publications

TitleAbstractYear(sorted ascending)
Filter
PMID
Filter
climate change and infectious diseases in north america: the road ahead.global climate change is inevitable--the combustion of fossil fuels has resulted in a buildup of greenhouse gases within the atmosphere, causing unprecedented changes to the earth's climate. the fourth assessment report of the intergovernmental panel on climate change suggests that north america will experience marked changes in weather patterns in coming decades, including warmer temperatures and increased rainfall, summertime droughts and extreme weather events (e.g., tornadoes and hurricanes) ...018332386
arthropod-borne disease in canada: a clinician's perspective from the 'cold zone'.arthropod-borne diseases do not occur commonly in canada. nevertheless, canadians run the risk of contracting certain infections within the country during arthropod season, as well as when travelling abroad. therefore, it is important that clinicians are aware of the possible occurrence of arthropod-borne diseases, and consider them in their differential diagnoses. the present review is divided into two sections: arthropod-borne diseases or disease agents documented in canada, and imported arthr ...020177520
multiplex sybr® green-real time pcr (qpcr) assay for the detection and differentiation of bartonella henselae and bartonella clarridgeiae in cats.a novel sybr® green-real time polymerase chain reaction (qpcr) was developed to detect two bartonella species, b. henselae and b. clarridgeiae, directly from blood samples. the test was used in blood samples obtained from cats living in animal shelters in southern brazil. results were compared with those obtained by conventional pcr targeting bartonella spp. among the 47 samples analyzed, eight were positive using the conventional pcr and 12 were positive using qpcr. importantly, the new qpcr de ...024626408
anaplasmosis in a dog on vancouver island. 026130842
inclusion bodies in tick-borne diseases diagnosed in patients from northern wisconsin. 019574488
update on tick-borne rickettsioses around the world: a geographic approach.tick-borne rickettsioses are caused by obligate intracellular bacteria belonging to the spotted fever group of the genus rickettsia. these zoonoses are among the oldest known vector-borne diseases. however, in the past 25 years, the scope and importance of the recognized tick-associated rickettsial pathogens have increased dramatically, making this complex of diseases an ideal paradigm for the understanding of emerging and reemerging infections. several species of tick-borne rickettsiae that wer ...024092850
ixodes pacificus cooley and kohls, 1943: its life-histor and occurrence. 19685693986
isolation of a spotted fever group rickettsia from the pacific coast tick, ixodes pacificus, in oregon.a rickettsia of the spotted fever group was isolated on three occasions from ixodes pacificus in western oregon. these isolations, and additional evidence furnished by complement fixation tests on guinea pigs inoculated with other oregon ticks of this species, indicate that the association of this rickettsia with the pacific coast tick may be widespread. this is the first isolation of a spotted fever group rickettsia from i. pacificus. because the oregon isolates are mildly virulent for guinea p ...1976937637
the distribution in oregon of ixodes pacificus, dermacentor andersoni, and dermacentor occidentalis with a note on dermacentor variabilis (acarina: ixodidae). 1977845890
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
tick paralysis in a western harvest mouse.an engorging female ixodes pacificus was observed on a western harvest mouse (reithrodontomys megalotis) in humboldt county, california. the mouse demonstrated a flaccid paraplegia, but it appeared to recover fully after the tick was removed.19807431519
serotypes of tick-borne spotted fever group rickettsiae from western california.a rickettsial survey of ixodid ticks known to bite man was conducted in 1979 in four coastal counties of california to obtain isolates from tick species that might be involved in the transmission of spotted fever-like illnesses, and to examine serologic characteristics of the rickettsiae relative to defined members of the spotted fever group (sfg). one hundred and seventy (19.4%) of 877 ticks comprising three species were shown by hemolymph test to harbor rickettsia-like organisms. a total of 85 ...19816789691
helical mycoplasmas (spiroplasmas) from ixodes ticks.a new spiroplasma isolated from ixodes pacificus collected in oregon was serologically and morphologically distinct from known spiroplasmas. the new spiroplasma could also be isolated in tick cell cultures. discovery of a new fastidious mycoplasma in ticks offers opportunities to explore the possible role of these agents in human and animal diseases.19817233197
characterization and taxonomic status of tick spiroplasmas: a review.three serologically distinct groups of spiroplasmas have been recovered from ticks. spiroplasma mirum strains (from rabbit ticks, haemaphysalis leporispalustris) and y32 group (vi) spiroplasmas (from ixodes pacificus) are the only spiroplasmas to have a clear association with these arthropods. group (vi) spiroplasmas are distinguished by an unusual nonhelical morphology and their capacity to hemadsorb guinea pig erythrocytes. s. mirum strains are unique in their ability to induce cataracts or le ...19836382825
discovery of the lyme disease spirochete and its relation to tick vectors.the various hypotheses concerning the etiologic agent of erythema chronicum migrans of europe and of lyme disease in the united states are reviewed, and an account of events that led to the discovery of the causative spirochetal agent in ixodes dammini is presented. spirochetes morphologically and antigenically similar, if not identical to, the organism detected in i. dammini were also found for the first time in ixodes pacificus and ixodes ricinus, the vectors hitherto incriminated, respectivel ...19846516454
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
the western black-legged tick, ixodes pacificus: a vector of borrelia burgdorferi.to determine the significance of the western black-legged tick, ixodes pacificus, as a vector of the lyme disease spirochete, borrelia burgdorferi, a tick/spirochete survey was conducted in northern california and southwestern oregon from 1982 to 1984. of 1,687 adult ticks collected off vegetation, 25 (1.48%) contained spirochetes. of 715 ticks from oregon, 14 (1.96%) were infected whereas 11 (1.13%) of 972 ticks from california harbored spirochetes. an isolate of 1 of the spirochetes reacted sp ...19853898886
surveillance of lyme disease in the united states, 1982.lyme disease is a tick-borne illness that has been reported from three regions in the united states--the northeast, midwest, and west--which correspond to the distribution of the recognized vectors of the disease, ixodes dammini and ixodes pacificus. in 1982, a surveillance system designed to define the morbidity and geographic distribution for lyme disease by using a clinical case definition received information on 491 definite cases and 38 probable cases. of the definite cases, 489 were acquir ...19853998509
ixodes pacificus (acari: ixodidae): population dynamics and distribution on columbian black-tailed deer (odocoileus hemionus columbianus). 19854045944
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
transovarial and transstadial passage of borrelia burgdorferi in the western black-legged tick, ixodes pacificus (acari: ixodidae).transovarial and transstadial passage of borrelia burgdorferi was demonstrated for the first time in the western black-legged tick, ixodes pacificus. one of three field-collected females with spirochetes in ovarial tissues produced 100% infected progeny that maintained the spirochetes transstadially and in 4 of 5 cases passed them via eggs to as many as 97% of f2 filial ticks. the progeny infected ovarially and by subsequent transstadial passage had generalized tissue infections that exhibited r ...19873605502
characterization of borrelia burgdorferi strains isolated from ixodes pacificus ticks in california.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
questing behavior of ixodes pacificus (acari: ixodidae) in relation to meteorological and seasonal factors. 19883193432
complete heart block in a dog seropositive for borrelia burgdorferi. similarity to human lyme carditis.lyme disease has been recognized in humans since 1975 when it was associated with an outbreak of oligoarthritis in children in lyme, connecticut. erythema chronicum migrans (ecm) is a clinical marker for the human disease, which usually appears within 3 to 32 days after an infected tick bite. lyme disease is caused by spirochete, borrelia burgdorferi, which is vectored by the hard ticks ixodes dammini or ixodes pacificus in the united states. in humans, lyme disease has been found to cause a var ...19883225808
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
epizootiology of borrelia in ixodes tick vectors and reservoir hosts.four north american and two european species of ixodes ticks harbor borreliae. three of the north american species--ixodes dammini, ixodes scapularis, and ixodes pacificus--and two old world species--ixodes ricinus and ixodes persulcatus--feed on a wide range of hosts, including humans; the north american ixodes dentatus has a predilection for cottontail rabbits and rarely parasitizes humans. in lyme disease foci in north america where i. dammini is common, borrelia burgdorferi or similar types ...19892682957
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
treatment of clothing with a permethrin spray for personal protection against the western black-legged tick, ixodes pacificus (acari: ixodidae).the synthetic pyrethroid, permethrin, when applied to clothing with a pressurized spray at an application rate estimated previously to be 4 micrograms a.i./cm2, was found to be 100% effective for personal protection against all three parasitic stages of the western black-legged tick, ixodes pacificus cooley and kohls. this tick has been implicated as the primary vector of the lyme disease spirochete (borrelia burgdorferi) to humans in the far-western united states. periods of exposure to permeth ...19892743839
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
characterization of a tick isolate of borrelia burgdorferi that possesses a major low-molecular-weight surface protein.an unusual strain of borrelia burgdorferi (dn 127 cl 9-2) that was isolated from an ixodes pacificus tick did not react with monoclonal antibodies (mabs) to ospa and ospb surface proteins, which are found in most u.s. strains. the strain exhibited an abundant protein with an apparent molecular weight of 25,000 (25k protein). a mab, 86 dn-1, that was prepared to the 25k protein was used in studies on the effect of proteases on the intact spirochetes, immune electron microscopy, and western blot ( ...19902199499
susceptibility of the western fence lizard (sceloporus occidentalis) to the lyme borreliosis spirochete (borrelia burgdorferi).attempts to infect juvenile and adult western fence lizards (sceloporus occidentalis) with the lyme borreliosis spirochete (borrelia burgdorferi) were largely unsuccessful. spirochetes could not be isolated from the blood and various tissues of 14 lizards 21-32 days after they had been inoculated ip (n = 8) or sc (n = 6) with 10(6) or 10(8) b. burgdorferi representing 3 tick isolates, although 1 lizard apparently developed a transitory spirochetemia lasting 2 days. similarly, spirochetes could n ...19902301709
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
host-seeking behavior of adult ixodes pacificus (acari: ixodidae) as determined by flagging vegetation.diurnal host-seeking by adults of the western black-legged tick, ixodes pacificus cooley & kohls in relation to vegetative habitat type and meterological factors was investigated at a coastal and an inland site in northern california. host-seeking behavior and relative tick abundance were determined with a tick drag method from late fall to midwinter 1987-1988. at the inland site, tick abundance usually was significantly greater in chaparral-grassland ecotones than in adjoining dense chaparral o ...19902332872
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
lyme disease: a clinical review.lyme disease is caused by the spirochete borrelia burgdorferi, which is transmitted primarily by ixodes dammini ticks in the northeast and upper midwest, by ixodes pacificus in western states, and by ixodes ricinus in europe. lyme disease can affect the skin, nervous system, heart, eyes, and joints, and is diagnosed in patients with these characteristic clinical features: exposure to an endemic area and usually a positive serologic test for b. burgdorferi six or more weeks after infection. full ...19911944020
duration of attachment by mites and ticks on the iguanid lizards sceloporus graciosus and uta stansburiana.duration of attachment was determined for the mites neotrombicula californica and geckobiella texana and the tick ixodes pacificus on the iguanid lizards sceloporus graciosus and uta stansburiana from southern california. neotrombicula californica infestations lasted approximately 1 wk. attachment of ixodes pacificus larvae and nymphs lasted approximately 8 days on s. graciosus and 16 days on u. stansburiana. geckobiella texana remained attached to s. graciosus for 5 days and to u. stansburiana ...19911758043
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
lyme borreliosis: ten years after discovery of the etiologic agent, borrelia burgdorferi.since the recovery of its causative agent, borrelia burgdorferi, in 1981, lyme borreliosis has become the most prevalent tick-borne disease in the united states as well as in europe. its steadily increasing clinical spectrum now includes erythema migrans, acrodermatitis chronica atrophicans, lymphadenosis beniga cutis, arthritis, myocarditis, progressive meningoencephalitis, myositis, and various ocular and skin disorders. the true incidence of lyme borreliosis in the world is unknown. in the un ...19911917043
tick information sheet. the western black-legged tick. ixodes pacificus. 19912014628
integumental lesions caused by ectoparasites in a wild population of the side-blotched lizard (uta stansburiana).histopathological effects of ectoparasites on integument were examined for a wild population of the side-blotched lizard uta stansburiana. these included the trombiculid neotrombicula californica, the pterygosomatid mite geckobiella texana; the macronyssid mite ophionyssus natricis (macronyssidae) and the ixodid tick ixodes pacificus. a diffuse inflammatory response occurred at the site of chigger and tick attachment which consisted of histiocyte, heterophil, fibroblast and lymphocyte infiltrati ...19912023329
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
field studies on lyme disease in north america.the primary tick vector of borrelia burgdorferi in eastern and central north america is ixodes dammini; in western north america, ixodes pacificus. searching for the appropriate vector is the first step in determining whether a region is endemic and enzootic for the spirochete b burgdorferi, the etiological agent of lyme disease, followed by examination of the ticks (questing or already attached to hosts) and wildlife for the spirochete. questing ticks can be collected through a variety of metho ...199122529709
consensus conference on lyme disease. 199122529708
occurrence of ixodes pacificus (parasitiformes: ixodidae) in arizona.adults and immatures of ixodes pacificus cooley & kohls were collected by flagging vegetation and from lizards during a 3-mo period in the hualapai mountain park, mohave county, az, in 1991. collections were made at altitudes > or = 2,134 m. two of 48 gut-salivary gland extracts of adult ticks were positive by ifa using a monoclonal antibody (h5332) specific to borrelia burgdorferi. these are the first records of i. pacificus and of spirochetes tentatively identified as b. burgdorferi in arizona ...19921460624
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
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
mark and recapture of adult ixodes pacificus (acari: ixodidae) to determine the effect of repeated removal sampling on tick abundance.the effect of biweekly flagging on adult ixodes pacificus cooley & kohls abundance was determined by using mark-recapture techniques. ticks were recaptured up to three times during the 12-wk study, and increasingly higher proportions of marked ticks were recaptured as the study progressed. by week 6 of the study, 46% of the collected ticks had been marked, and on the final sampling date, all ticks had been captured previously. removal sampling would have substantially reduced estimates of the ab ...19938271251
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
an ospa antigen-capture enzyme-linked immunosorbent assay for detecting north american isolates of borrelia burgdorferi in larval and nymphal ixodes dammini.an antigen-capture enzyme-linked immunosorbent assay (elisa) was developed for detecting north american isolates of borrelia burgdorferi in larval, nymphal, and adult ticks. the assay uses an anti-ospa monoclonal antibody (h5332) for antigen capture and biotin-labelled polyclonal sera with streptavidinhorseradish peroxidase for signal generation. the assay recognized 15 of 15 north american b. burgdorferi isolates and did not cross-react with spirochete antigens of borrelia hermsii, borrelia tur ...19938432812
conspecificity of the ticks ixodes scapularis and i. dammini (acari: ixodidae).reciprocal crosses between ixodes dammini spielman, clifford, piesman & corwin from massachusetts and ixodes scapularis say from georgia produced offspring through the f3 generation when the experiment was discontinued. reciprocal i. dammini x ixodes pacificus cooley & kohls (california) and i. scapularis x i. pacificus crosses produced f1 progeny; however, all progeny were sterile. assortative mating experiments between i. dammini and i. scapularis indicated that males and females of both speci ...19938433346
efficiency of transovarial transmission of the lyme disease spirochete, borrelia burgdorferi, in the western blacklegged tick, ixodes pacificus (acari: ixodidae).the efficiency of transovarial transmission of borrelia burgdorferi johnson, schmid, hyde, steigerwalt & brenner was evaluated in ixodes pacificus cooley & kohls collected from two areas of northern california where lyme disease is endemic. in total, 132 (8.8%) of 1,499 replete females examined by direct immunofluorescence were demonstrated to be infected with b. burgdorferi. larvae or eggs from 119 of these females were examined for the presence of spirochetes by direct immunofluorescence, plac ...19938433348
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
species of borrelia distinguished by restriction site polymorphisms in 16s rrna genes.three phyletic groups of borrelia associated with lyme disease, b. burgdorferi, b. garinii and group vs461 can be distinguished from each other and other species of borrelia by bfai restriction site polymorphisms in pcr amplified 16s rrna genes. one strain isolated from an ixodes pacificus tick in california that was previously unclassifiable was distinguishable from b. burgdorferi by an mn/i restriction site polymorphism.19937691681
vector competence of ixodes pacificus and dermacentor occidentalis (acari: ixodidae) for various isolates of lyme disease spirochetes.the vector competence of the western black-legged tick, ixodes pacificus cooley & kohls, and the pacific coast tick, dermacentor occidentalis marx, for the lyme disease spirochete (borrelia burgdorferi johnson, schmid, hyde, steigerwalt & brenner) was compared. rabbits, hamsters, and the deer mouse, peromyscus maniculatus (wagner), were injected with cultured spirochetes or infected tick-suspensions, or were fed upon by spirochete-infected ticks. five of seven isolates used as inocula were reiso ...19948057316
transmission of borrelia burgdorferi by ixodes pacificus nymphs and reservoir competence of deer mice (peromyscus maniculatus) infected by tick-bite.the transmission of borrelia burgdorferi to deer mice (peromyscus maniculatus) by ixodes pacificus nymphs was investigated experimentally. deer mice were exposed to infected nymphs for 24, 48, or 72 hr, or until ticks had fed to repletion (> or = 96 hr). infection status of hosts was assessed 4 wk later by culture of ear-punch biopsies in bsk ii medium and by indirect immunofluorescence. eight mice exposed to ticks for 24 hr did not become infected. in contrast, infection was acquired by 1 of 9 ...19957707191
spiroplasma ixodetis sp. nov., a new species from ixodes pacificus ticks collected in oregon.eight strains of mollicutes were isolated from pooled suspensions prepared from western black-legged ticks (ixodes pacificus) collected in oregon. morphologic examination by electron and dark-field microscopic techniques showed that each strain consisted of a mixture of motile, tightly coiled helical cells, small coccoid cells with diameters ranging from 300 to 500 nm, and pleomorphic, straight or branched filamentous forms. all cellular forms were surrounded by a single cytoplasmic membrane, an ...19957857803
hemocytic rickettsia-like organisms in ticks: serologic reactivity with antisera to ehrlichiae and detection of dna of agent of human granulocytic ehrlichiosis by pcr.ixodid ticks were collected from connecticut, massachusetts, missouri, pennsylvania, rhode island, and british columbia (canada) during 1991 to 1994 to determine the prevalence of infection with hemocytic (blood cell), rickettsia-like organisms. hemolymph obtained from these ticks was analyzed by direct and indirect fluorescent antibody (fa) staining methods with dog, horse, or human sera containing antibodies to ehrlichia canis, ehrlichia equi, or rickettsia rickettsii. of the 693 nymphal and a ...19958567911
evidence implicating nymphal ixodes pacificus (acari: ixodidae) in the epidemiology of lyme disease in california.to 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
diel activity of nymphal dermacentor occidentalis and ixodes pacificus (acari: ixodidae) in relation to meteorological factors and host activity periods.relation of diel activity and questing behavior of nymphal dermacentor occidentalis marx and ixodes pacificus cooley & kohls to meteorological factors was investigated in a shaded versus a sun-exposed outdoor arena. oak-woodland soil covered partially with leaf litter and small rocks, and 24 vertically oriented grass stems 2.5, 5.0, 10.0, and 20.0 cm tall were provided as substrate and potential questing sites. tick activity and weather conditions were monitored bihourly during 15 diel (24-h) ex ...19957616519
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
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
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
ixodes pacificus (acari: ixodidae) as a vector of ehrlichia equi (rickettsiales: ehrlichieae).ehrlichia equi, a rickettsia described from horses in california 30 yr ago, causes equine granulocytic ehrlichiosis throughout the americas and possibly europe. here, we report experimental transmission of e. equi from infected to susceptible horses through bites of western blacklegged ticks, ixodes pacificus (cooley & kohls). in preliminary field studies, only i. pacificus consistently infested horses and vegetation at 3 locations with contemporary cases of equine ehrlichosis, and in particular ...19968906897
nested polymerase chain reaction for detection of ehrlichia equi genomic dna in horses and ticks (ixodes pacificus).a nested polymerase chain reaction for detecting ehrlichia equi in horses and ticks (ixodes pacificus) was developed. a major second-round pcr product of 928 bp could be readily visualized in ethidium bromide-stained agarose minigels. an internal probe was used to verify the identity of the amplified product by non-radioactive (digoxigenin-based) southern blotting; additional confirmation was provided by dna sequence analysis. a dilution study testing the sensitivity of the pcr indicated that dn ...19968966998
lyme borreliosis in the southern united states: a review.lyme borreliosis (lyme disease) is the most often reported arthropod transmitted disease in humans in the u.s.a. although it has been reported from 43 states, cases are especially abundant in the mid-atlantic and northeastern regions. borrelia burgdorferi, the etiologic agent, is transmitted primarily by the western blacklegged tick (ixodes pacificus) in far western north america, and by the blacklegged tick (ixodes scapularis) in eastern north america. although lyme disease cases have been repo ...19968973401
field and laboratory studies on the timing of oviposition and hatching of the western black-legged tick, ixodes pacificus (acari: ixodidae).the timing of oviposition and hatching of ixodes pacificus was investigated in the field and at constant temperatures in the laboratory. replete females held at temperatures between 9 and 29 degrees c began depositing eggs a mean of 9-70 days after drop off. egg masses held between 12 and 25 degrees c commenced hatching 25-178 days after the onset of oviposition. eggs held at 9 or 29 degrees c did not hatch. the lower temperature thresholds for development (ltd) for oviposition and hatching were ...19969004494
nested polymerase chain reaction for detection of ehrlichia risticii genomic dna in infected horses.a nested polymerase chain reaction was developed for amplifying a 529-bp segment of the 16s ribosomal rna gene of ehrlichia risticii from equine buffy coat cells. confirmation of identity of the amplified bands was accomplished by southern hybridization and dna sequencing. the study indicated a detection limit of > 10 copies of the target gene, and specificity for e. risticii as based on a panel of test rickettsiae. ticks (ixodes pacificus) collected in an area of northern california enzootic fo ...19979106958
an ehrlichia strain from a llama (lama glama) and llama-associated ticks (ixodes pacificus).an ehrlichia was identified in the blood of a diseased llama (lama glama). sequencing of its 16s rrna gene showed the ehrlichia to be closely related to members of the ehrlichia phagocytophila genogroup. the agent was also found in a pool of ticks (ixodes pacificus) collected at the llama site.19979157118
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
ehrlichia phagocytophila genogroup rickettsiae in ixodid ticks from california collected in 1995 and 1996.a total of 1,246 ixodid ticks collected in 1995 and 1996 from seven california counties were examined for the presence of ehrlichia phagocytophila genogroup rickettsiae by using a nested pcr technique. of 1,112 adult ixodes pacificus cooley and kohls ticks tested, nine pools, each containing five ticks, were positive (minimum percentage of ticks harboring detectable ehrlichiae, 0.8%). positive ticks were limited to four of the seven counties (sonoma, el dorado, santa cruz, and orange). in santa ...19979230373
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
two gynandromorphs of ixodes (ixodes) pacificus (acari: ixodidae) from california, usa. 19979332981
taxonomic status of ixodes neotomae and i. spinipalpis (acari: ixodidae) based on mitochondrial dna evidence.ixodes spinipalpis hadwen & nuttall and i. neotomae cooley are enzootic vectors of borrelia burgdorferi johnson, schmid, hyde, steigerwalt & brenner in western north america. the taxa overlap in host preference, habitat, and morphology. mitochondrial dna was compared between the taxa to test for reproductive isolation. a 300-bp region of the mitochondrial 16s ribosomal dna gene was amplified in 28 specimens of i. neotomae and 149 specimens of i. spinipalpis. these products were screened for sequ ...19979439125
borreliacidal factor in the blood of the western fence lizard (sceloporus occidentalis).in some populations of the western black-legged tick, ixodes pacificus, the prevalence of infection with lyme disease spirochetes (borrelia burgdorferi) in nymphal ticks exceeds those in adult ticks by 3-4-fold. experiments were conducted to determine if the reduced spirochetal prevalence in adult ticks is due to the presence of anti-borrelial antibodies or to another borreliacidal factor in the blood of the western fence lizard, sceloporus occidentalis, a primary host of subadult i. pacificus, ...19989488334
analysis of the organization of multicopy linear- and circular-plasmid-carried open reading frames in borrelia burgdorferi sensu lato isolates.plasmid cp8.3 of borrelia afzelii ip21 carries several open reading frames (orfs) and a 184-bp inverted repeat (ir) element. it has been speculated that this plasmid may encode factors involved in virulence or infectivity. in this report, we have characterized the distribution, molecular variability, and organization of orfs 1, 2, and 4 and the ir elements among isolates of the borrelia burgdorferi sensu lato complex. orfs 1 and 2 are contained within a segment of cp8.3 that is bordered by the i ...19989488408
serologic evidence of infection with ehrlichia spp. in wild rodents (muridae: sigmodontinae) in the united states.rodent (muridae: sigmodontinae) blood and sera collected from 14 states were tested for seroreactivity to a cultured isolate of the human granulocytic ehrlichiosis (hge) agent by using an indirect immunofluorescence assay. of the 1,240 samples tested, 136 (11%) were found to be reactive at titers of > or = 32. rodents with hge agent-specific antibodies were found in new york (23% of 491 samples; geometric mean endpoint titer [gmt] = 441), connecticut (11% of 100 samples; gmt = 481), california ( ...19989508298
inhibition of the production of anti-ospa borreliacidal antibody with t cells from hamsters vaccinated against borrelia burgdorferi.the serious morbidity associated with lyme borreliosis has focused considerable effort on the development of a comprehensive vaccine for protection against infection with borrelia burgdorferi. induction of borreliacidal antibody by vaccination or infection has been shown to correlate with protection of humans and animals against infection with the lyme spirochete. in this report, we showed that high levels of borreliacidal antibody (titer of 1,280) were produced in vitro when t and b cells from ...19989529074
nested pcr assay for detection of granulocytic ehrlichiae.a sensitive and specific nested pcr assay was developed for the detection of granulocytic ehrlichiae. the assay amplifies the 16s rrna gene and was used to examine acute-phase edta-blood and serum samples obtained from seven humans with clinical presentations compatible with human granulocytic ehrlichiosis. five of the seven suspected cases were positive by the pcr assay using dna extracted from whole blood as the template, compared with a serologic assay that identified only one positive sample ...19989542943
optimal sampling and spatial distribution of ixodes pacificus, dermacentor occidentalis and dermacentor variabilis ticks (acari: ixodidae).a common method for sampling tick populations is flagging, which is a method of dragging a white cloth over a plant substrate for a fixed distance along a transect. flagging over rough physical surfaces or using long subtransect lengths could lead to the underestimation of tick densities. using estimates of the drop-off rates of adult ixodes pacificus in flag sampling, optimal sampling schemes (the length and number of subtransects) were examined using the relationships between the tick drop-off ...19989588010
production and characterization of ehrlichia risticii, the agent of potomac horse fever, from snails (pleuroceridae: juga spp.) in aquarium culture and genetic comparison to equine strains.we report on the production and characterization of ehrlichia risticii, the agent of potomac horse fever (phf), from snails (pleuroceridae: juga spp.) maintained in aquarium culture and compare it genetically to equine strains. snails were collected from stream waters on a pasture in siskiyou county, calif., where phf is enzootic and were maintained for several weeks in freshwater aquaria in the laboratory. upon exposure to temperatures above 22 degrees c the snails released trematode cercariae ...19989620368
identification of a granulocytic ehrlichia strain isolated from a horse in switzerland and comparison with other rickettsiae of the ehrlichia phagocytophila genogroup.this case report describes a 12-year-old arabian mare with granulocytic ehrlichiosis. clinical signs included fever, apathy, anorexia, icterus, limb edema, and reluctance to move. examination of buffy coat smears revealed ehrlichia organisms in neutrophils and eosinophils. a band of 1,428 bp was amplified from dna of leukocytes via nested pcr and was identified as part of the ehrlichia 16s rrna gene. it differed from the gene sequences of ehrlichia phagocytophila and e. equi at two and three pos ...19989650957
experimental transmission of ehrlichia equi to horses through naturally infected ticks (ixodes pacificus) from northern california.we report the experimental transmission of ehrlichia equi from naturally infected ixodes pacificus ticks to horses. three weeks after exposure to ticks, two of three horses developed clinical signs compatible with e. equi infection, while one horse remained asymptomatic. 16s rrna gene pcr of blood leukocyte lysates was positive for all horses at various time points; two horses seroconverted. the 16s rrna gene sequences amplified from tick-exposed horses showed more than 99% homology to correspon ...19989650983
therapeutic effect of doxycycline in experimental subclinical canine monocytic ehrlichiosis: evaluation of a 6-week course.the efficacy of doxycycline treatment (10 mg/kg of body weight every 24 h for 42 days) in eliminating ehrlichia canis from four subclinically infected dogs was evaluated. one dog remained pcr positive, suggesting that 6 weeks of doxycycline treatment may not be sufficient to clear e. canis parasites from all subclinically infected dogs. serology (indirect immunofluorescent antibody assay) was shown to be unreliable in assessing recovery from the carrier state, as anti-e. canis antibodies persist ...19989650986
detection of ehrlichia risticii, the agent of potomac horse fever, in freshwater stream snails (pleuroceridae: juga spp.) from northern california.ehrlichia dna was identified by nested pcr in operculate snails (pleuroceridae: juga spp.) collected from stream water in a northern california pasture in which potomac horse fever (phf) is enzootic. sequencing of pcr-amplified dna from a suite of genes (the 16s rrna, groesl heat shock operon, 51-kda major antigen genes) indicated that the source organism closely resembled ehrlichia risticii, the causative agent of phf. the minimum percentage of juga spp. harboring the organism in the population ...19989687446
failure of ixodes ticks to inherit borrelia afzelii infection.to define conditions promoting inherited infection by lyme disease spirochetes in ixodes ticks, we variously infected ticks with borrelia afzelii and examined their progenies by dark-field microscopy, immunofluorescence, pcr, and serial passage. no episode of inherited infection was evident, regardless of instar or gender infected or frequency of exposure. we suggest that these spirochetes rarely, if ever, are inherited by vector ticks.19989687480
distribution of ixodes pacificus and ixodes scapularis re concurrent babesiosis and lyme disease. 19989704540
sequential evaluation of dogs naturally infected with ehrlichia canis, ehrlichia chaffeensis, ehrlichia equi, ehrlichia ewingii, or bartonella vinsonii.historically, disease manifestations in dogs seroreactive to ehrlichia canis antigens by indirect immunofluorescent antibody testing have been attributed to infection with either e. canis or ehrlichia ewingii. a 1996 study by dawson and colleagues provided pcr evidence that healthy dogs from southeastern virginia could be naturally infected with ehrlichia chaffeensis. this observation stimulated us to determine which ehrlichia spp. infected sick dogs that were referred to our hospital from the s ...19989705408
detection of ehrlichia phagocytophila dna in ixodes ricinus ticks from areas in switzerland where tick-borne fever is endemic.a total of 1,523 adult ixodes ricinus ticks were collected from regions where bovine ehrlichiosis is endemic and were examined for ehrlichia phagocytophila via pcr. of the ticks from cattle with ehrlichiosis, the ticks from healthy cattle, and the free-living ticks, 26.5% (18 of 68), 4.4% (35 of 802), and 0.8% (5 of 653), respectively, were positive.19989705425
human exposure to a granulocytic ehrlichia and other tick-borne agents in connecticut.indirect fluorescent-antibody (ifa) staining methods with ehrlichia equi (mrk or bds strains) and western blot analyses containing a human granulocytic ehrlichiosis (hge) agent (nch-1 strain) were used to confirm probable human cases of infection in connecticut during 1995 and 1996. also included were other tests for ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis (hme), babesia microti, and borrelia burgdorferi. thirty-three (8.8%) of 375 patients who had fever accompanied by m ...19989738027
genetic divergence and evolutionary instability in ospe-related members of the upstream homology box gene family in borrelia burgdorferi sensu lato complex isolates.a series of related genes that are flanked at their 5' ends by a conserved upstream sequence element called the upstream homology box (uhb) have been identified in borrelia burgdorferi. these genes have been referred to as the uhb or erp gene family. we previously demonstrated that among a limited number of b. burgdorferi isolates, the uhb gene family is variable in composition and organization. prior to this report the uhb gene family in other species of the b. burgdorferi sensu lato complex ha ...19989746562
reported distribution of ixodes scapularis and ixodes pacificus (acari: ixodidae) in the united states.lyme disease, caused by infection with borrelia burgdorferi, is the most frequently reported arthropod-borne disease in the united states. to develop a national map of the distribution of the vectors of b. burgdorferi to humans (ixodes scapularis say and ixodes pacificus cooley & kohls ticks), we sent questionnaires to acarologists, health officials, and lyme disease researchers; surveyed the 1966-1996 medline data base; and reviewed 1907-1995 national tick collection data. tick collection metho ...19989775584
molecular analysis of sequence heterogeneity among genes encoding decorin binding proteins a and b of borrelia burgdorferi sensu lato.immunization of mice with borrelia burgdorferi decorin binding protein a (dbpa), one of two gene products of the dbpba locus, has been shown recently to confer protection against challenge. hyperimmune dbpa antiserum killed a large number of b. burgdorferi sensu lato isolates of diverse phylogeny and origin, suggesting conservation of the protective epitope(s). in order to evaluate the heterogeneity of dbpa and dbpb and to facilitate defining the conserved epitope(s) of these antigens, the seque ...19989784533
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
infestation of the southern alligator lizard (squamata: anguidae) by ixodes pacificus (acari: ixodidae) and its susceptibility to borrelia burgdorferi.to investigate the reservoir potential of the southern alligator lizard, elgaria multicarinata (blainville), for the lyme disease spirochete, borrelia burgdorferi johnson, schmid, hyde, steigerwalt & brenner, 14 lizards were collected from 1 county on each side of the northern central valley of california. seven animals were collected from a placer county site (drivers flat) and a yolo county site (cache creek) where b. burgdorferi had been isolated previously from ixodes pacificus cooley & kohl ...19989835700
molecular biology and pathogenicity of mycoplasmas.the recent sequencing of the entire genomes of mycoplasma genitalium and m. pneumoniae has attracted considerable attention to the molecular biology of mycoplasmas, the smallest self-replicating organisms. it appears that we are now much closer to the goal of defining, in molecular terms, the entire machinery of a self-replicating cell. comparative genomics based on comparison of the genomic makeup of mycoplasmal genomes with those of other bacteria, has opened new ways of looking at the evoluti ...19989841667
first isolation and cultivation of borrelia burgdorferi sensu lato from missouri.five borrelia burgdorferi sensu lato isolates from missouri are described. this represents the first report and characterization of such isolates from that state. the isolates were obtained from either ixodes dentatus or amblyomma americanum ticks that had been feeding on cottontail rabbits (sylvilagus floridanus) from a farm in bollinger county, mo., where a human case of lyme disease had been reported. all isolates were screened immunologically by indirect immunofluorescence by using monoclona ...19989431909
amplification of ehrlichial dna from dogs 34 months after infection with ehrlichia canis.in order to determine whether dogs in the subclinical phase of canine monocytic ehrlichiosis (cme) are carriers of ehrlichia canis and to determine the significance of persistent indirect immunofluorescent anti-e. canis antibody titers during this phase, pcr was performed with blood, bone marrow, and splenic aspirates collected 34 months postinoculation from six clinically healthy beagle dogs experimentally infected with e. canis. at least one of the three samples (spleen, bone marrow, and blood ...19989431923
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
quantitative real-time pcr for detection of members of the ehrlichia phagocytophila genogroup in host animals and ixodes ricinus ticks.a taqman pcr was established for identification and quantitation of members of the ehrlichia phagocytophila group in experimentally infected cows and in ixodes ricinus ticks. the taqman pcr identified a 106-bp section of the 16s rrna gene by use of a specific fluorogenic probe and two primers. this technique was specific for members of the e. phagocytophila group, which include e. phagocytophila, ehrlichia equi, and the agent of human granulocytic ehrlichiosis. the taqman system identified 10 co ...199910203480
Displaying items 1 - 100 of 512