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acquisition of different isolates of anaplasma phagocytophilum by ixodes scapularis from a model animal.the prevalence of etiologic agents in ticks reflects the intensity of their transmission in natural cycles and is an important measure of their potential to cause human disease. the distribution of anaplasma phagocytophilum within the range of its primary vectors is patchy. even nearby sites differ dramatically in the prevalence of anaplasma in questing ticks. we hypothesized that this irregular distribution may be due in part to variations in acquisition rates of different isolates of a. phagoc ...200415018773
comparison of the nucleotide sequences of 16s rrna, 444 ep-ank, and groesl heat shock operon genes in naturally occurring ehrlichia equi and human granulocytic ehrlichiosis agent isolates from northern california.we examined 11 naturally occurring isolates of ehrlichia equi in horses and two human granulocytic ehrlichiosis agent isolates in california for sequence diversity in three genes. ehrlichia equi isolates were from sierra (n = 6), mendocino (n = 3), sonoma (n = 1), and marin (n = 1) counties, and human granulocytic ehrlichiosis (hge) agent isolates were obtained from humboldt county. pcr with specific primers for 16s rrna, 444 ep-ank and groesl heat shock operon genes successfully produced amplic ...200010747108
seroepidemiologic survey of antibodies to ehrlichia equi in horses of northern california.the prevalence of antibodies to ehrlichia equi in horses from the foothill regions of northern california and from the sacramento valley (non-foothill area) was determined, using an indirect fluorescent antibody test. horses from foothill regions had a higher prevalence of seropositivity (10.4%) and higher titer (1:10 to 1:80) than did those from non-foothill regions (3.1%; titer less than or equal to 1:10). fifty percent of healthy horses on a foothill farm enzootic for e equi had titer to e eq ...19902195000
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
spatial distribution of seropositivity to the causative agent of granulocytic ehrlichiosis in dogs in california.to assess spatial and temporal patterns of seroprevalence among dogs in california to the causative agent of granulocytic ehrlichiosis (ge).200111592326
antibiotic susceptibilities of anaplasma (ehrlichia) phagocytophilum strains from various geographic areas in the united states.we tested the antibiotic susceptibilities of eight strains of anaplasma phagocytophilum (the agent of human granulocytic ehrlichiosis) collected in various geographic areas of the united states, including minnesota, wisconsin, california, and new york. the results are homogeneous and show that doxycycline, rifampin, and levofloxacin are the most active antibiotics against these strains in vitro.200312499227
ehrlichia spp. in cervids from california.blood samples from six mule deer (odocoileus hemionus hemionus), 15 black-tailed deer (o. hemionus columbianus), and 29 elk (cervus elaphus nannodes) were assayed for human monocytic and human granulocytic ehrlichiosis (hge) by polymerase chain reaction (pcr), dna sequencing, and serology to determine whether or not cervids are involved in the maintenance of these potential human pathogens in california (usa). the deer were sampled in august to october 1992-95. the 29 tule elk from point reyes n ...19989813842
acarologic risk of exposure to emerging tick-borne bacterial pathogens in a semirural community in northern california.an 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
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
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
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
association of ixodes pacificus (acari: ixodidae) with the spatial and temporal distribution of equine granulocytic ehrlichiosis in california.this study was conducted to determine if the biology of certain ticks associated with horses regulates the spatial and temporal distribution of equine granulocytic ehrlichiosis (ege) in california north of monterey county. we compared the spatial and temporal distribution of ege cases with the seasons of activity and life histories of ticks that infest horses. spatially, cases collected from equine veterinarians clustered around each other in a manner different from the way in which control citi ...199910534948
human granulocytic ehrlichiosis in northern california: two case descriptions with genetic analysis of the ehrlichiae.we report two cases of human granulocytic ehrlichiosis (hge) that occurred in northern california in summer 1998. patients had fever, malaise, and myalgia, reported tick bites, had moderate thrombocytopenia, and had normal or slightly elevated liver enzyme activities. ehrlichial inclusions were observed in the blood of one patient, and hge-agent dna was amplified by pcr from both patients. genetically, the strains resembled horse isolates from northern california. the close spatial and temporal ...199910476747
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
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
evidence of multiple zoonotic agents in a wild rodent community in the eastern sierra nevada.this study aimed to describe the occurrence of yersinia pestis, rickettsia rickettsii, anaplasma phagocytophilum, and ectoparasites in a wild rodent community in the eastern sierra nevada. from may to september 2006, rodents were live-trapped, examined for ectoparasites, and blood was collected. all rodents were serologically tested for antibodies to y. pestis, r. rickettsii, and a. phagocytophilum; in addition, blood samples and ectoparasites were tested by pcr to detect the presence of these z ...200818689664
investigation of bartonella infection in ixodid ticks from california.a total of 1253 ixodid ticks (254 tick pools) collected between the end of 1995 and the spring of 1997 from six california counties (el dorado, los angeles, orange, santa cruz, shasta and sonoma) were examined for the presence of bartonella dna by pcr of the citrate synthase gene. of 1,119 adult ixodes pacificus ticks tested, 26 (11.6%) of 224 pools, each containing five ticks, were positive (minimum percentage of ticks harboring detectable bartonella dna, 2.3%). bartonella pcr-positive ticks we ...200212135237
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
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
infection in two dogs with an agent resembling ehrlichia equi. 19827061334
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
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
granulocytic ehrlichiosis and tick infestation in mountain lions in california.forty-seven mountain lions (puma concolor) collected year-round in 1996 to 1998 from the sierra nevada foothills, the northern coast ranges, and in monterey county (california, usa) were examined for infestation with ixodes pacificus and dermacentor variabilis ticks. ticks were found predominantly in winter and spring. the seroprevalence of granulocytic ehrlichiae (ge) antibodies (ehrlichia equi or the agent of human granulocytic ehrlichiosis) was 17% and the pcr-prevalence of dna characteristic ...199910574529
equine ehrlichiosis in northern california: 49 cases (1968-1981).case records of horses with equine ehrlichiosis (ehrlichia equi) at the university of california veterinary medical teaching hospital and ackerman creek large animal clinic were analyzed for evaluation of clinical signs, time of onset, hematologic values, response to treatment, and recovery. equine ehrlichiosis was found to be seasonal in horses in the foothills of northern california, with higher incidence than reported previously. the horses developed fever, anorexia, depression, limb edema, i ...19873558086
dusky-footed wood rats (neotoma fuscipes) as reservoirs of granulocytic ehrlichiae (rickettsiales: ehrlichieae) in northern california.dusky-footed wood rats (neotoma fuscipes) and peromyscus sp. mice (p. maniculatus and p. truei) were collected from one site in placer county, one site in santa cruz county, and two sites in sonoma county in northern california. serum or plasma samples from 260 rodents were tested for antibodies to the agent of human granulocytic ehrlichiosis. of these, samples from 25 wood rats (34% of those tested) and 10 (8%) peromyscus sp. mice were found to be seropositive, but only those from one site. pcr ...199910488199
evidence of tick-borne organisms in mule deer (odocoileus hemionus) from the western united states.free-ranging mule deer (md; odocoileus hemionus) from arizona and california were tested for evidence of infection with several tick-borne pathogens, including species of ehrlichia, anaplasma, babesia, and borrelia. of 125 mule deer tested from arizona, 29 (23%) and 11 (9%) had antibodies reactive to e. chaffeensis and a. phagocytophilum by indirect immunofluorescent antibody testing, respectively; none of the six md tested from california were seropositive. using a commercial competitive elisa ...200516417431
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
association between polyarthritis and thrombocytopenia and increased prevalence of vectorborne pathogens in californian dogs. 200717277299
a prospective study of canine infective endocarditis in northern california (1999-2001): emergence of bartonella as a prevalent etiologic agent.a prospective study was performed (june 1999 to may 2001) to determine the incidence of infective endocarditis (ie) due to bartonella in dogs in northern california and to compare these patients with other dogs with ie. ie was diagnosed antemortem based on clinical signs and echocardiography in 18 dogs. the etiologic agent was bartonella sp. in 5 dogs (28%) and was diagnosed by high seroreactivity to bartonella (titer > 1:512; range, 1:1,024-1:4,096); and confirmed postmortem by positive polymer ...200414765733
ehrlichia equi infection of horses from minnesota and wisconsin: detection of seroconversion and acute disease investigation.equine granulocytic ehrlichiosis (ege) is caused by infection with ehrlichia equi. ege has been reported primarily in northern california, where e equi is transmitted by the tick ixodes pacificus. reports of ege and the emergence of human granulocytic ehrlichia in minnesota prompted a seroprevalence study of e equi in horses of minnesota and wisconsin. tick (ixodes scapularis) endemic areas of minnesota and wisconsin were compared to nonendemic regions of minnesota. indirect fluorescent antibody ...200010830537
effects of anaplasma phagocytophilum infection on the molting success of ixodes scapularis (acari: ixodidae) larvae.we assessed the effects of sympatric (occupying the same or overlapping geographic areas) and allopatric (occurring in separate geographic areas) isolates of anaplasma phagocytophilum on the survival of ixodes scapularis say larvae that were derived from ticks collected in bridgeport, ct. seven isolates of a. phagocytophilum, originating from different geographic regions of the united states, were tested: four isolates from the northeast (bridgeport, dawson, gaillard, and ny-8), two from the mid ...200415185953
environmental factors associated with bartonella vinsonii subsp. berkhoffii seropositivity in free-ranging coyotes from northern california.bartonella vinsonii subsp. berkhoffii is a newly recognized pathogen of domestic dogs and humans. coyotes (canis latrans) are considered an important reservoir of this bacterium in the western united states, but its vectors are still unknown. our objective was to identify environmental factors associated with bartonella antibody prevalence in 239 coyotes from northern california, using an enzyme-linked immunosorbent assay. in addition, associations were evaluated between b. v. berkhoffii and two ...200516011426
serologic and molecular evidence of ehrlichia spp. in coyotes in california.in order to determine the role of coyotes in the epidemiology of granulocytic and monocytic ehrlichial agents in california (usa), we tested 149 serum samples for antibodies against ehrlichia equi, e. risticii, and e. canis, using an indirect immunofluorescent antibody test. polymerase chain reaction (pcr) assay was used to survey for the presence of members of the e. phagocytophila genogroup, e. risticii and e. canis in blood samples of 95 coyotes. sixty-eight (46%) samples were seropositive fo ...200010941735
survey of ixodes pacificus ticks in california reveals a diversity of microorganisms and a novel and widespread anaplasmataceae species.ixodes pacificus ticks can harbor a wide range of human and animal pathogens. to survey the prevalence of tick-borne known and putative pathogens, we tested 982 individual adult and nymphal i. pacificus ticks collected throughout california between 2007 and 2009 using a broad-range pcr and electrospray ionization mass spectrometry (pcr/esi-ms) assay designed to detect a wide range of tick-borne microorganisms. overall, 1.4% of the ticks were found to be infected with borrelia burgdorferi, 2.0% w ...201526375033
polymorphism and transcription at the p44-1/p44-18 genomic locus in anaplasma phagocytophilum strains from diverse geographic regions.a polymorphic multigene family (p44) of anaplasma phagocytophilum encodes the immunodominant 44-kda major outer membrane proteins. with p44-specific pcr and gene-specific probes, p44-1 was found in all human isolates from new york state but not in isolates from minnesota, whereas p44-18 and two other p44 species were found in isolates from both regions. we therefore sequenced the genomic locus corresponding to the p44-1/p44-18 tandem locus of a. phagocytophilum hz in 14 other geographically dive ...200415385454
reactivity of human sera to different strains of granulocytic ehrlichiae in immunodiagnostic assays.sera from 35 patients diagnosed with human granulocytic ehrlichiosis in connecticut were tested by indirect ifa staining methods with 5 strains of ehrlichia equi or the human granulocytic ehrlichiosis agent to assess the suitability of different strains in laboratory analyses. antigens included horse-derived infected neutrophils (mrk and bds strains) and human isolates cultured in human promyelocytic leukemia cells (nch-1, rch, and webster). of 35 sera, 23 (65.7%) reacted to all 5 strains. serop ...19989815246
clinical, epidemiologic, and environmental surveillance for ehrlichiosis and anaplasmosis in an endemic area of northern california.two forms of tick-borne leukocytotropic rickettsioses have been recognized in california since the mid-1990s: human monocytic ehrlichiosis (hme) caused by ehrlichia chaffeensis and human granulocytic anaplasmosis (hga) caused by anaplasma phagocytophilum. between 1997 and 1999, two cases of hme and four cases of hga were diagnosed in residents of southern humboldt county, california. environmental followup at case-patients' residences revealed dense populations of ixodes pacificus ticks, particu ...200516007950
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
the ecology of tick-transmitted infections in the redwood chipmunk (tamias ochrogenys).the redwood chipmunk contributes to the maintenance of tick-borne diseases in northern california. the range of redwood chipmunks overlaps that of western black-legged ticks and tick-borne disease, including granulocytic anaplasmosis and lyme borreliosis. chipmunks have high anaplasma phagocytophilum pcr- and seroprevalence, are infested with a diversity of ixodes spp. ticks, and are reservoir competent for borrelia burgdorferi. we hypothesized that chipmunks could maintain tick-borne disease on ...201121643481
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
spatial distribution of seroprevalence for anaplasma phagocytophilum, borrelia burgdorferi, ehrlichia canis, and dirofilaria immitis in dogs in washington, oregon, and california.background: in the us little spatially defined information regarding exposure to most vector-borne pathogens in dogs is available for the states of california (ca), oregon (or), and washington (wa). objectives: the purpose of the present study was to evaluate the spatial distribution of seroprevalence for 4 vector-borne pathogens, anaplasma phagocytophilum, borrelia burgdorferi, ehrlichia canis, and dirofilaria immitis, across the 3 western coastal states of the contiguous united states that ext ...201121827514
molecular characterization reveals distinct genospecies of anaplasma phagocytophilum from diverse north american hosts.anaplasma phagocytophilum is an emerging tick-borne pathogen that infects humans, domestic animals and wildlife throughout the holarctic. in the far-western united states, multiple rodent species have been implicated as natural reservoirs for a. phagocytophilum. however, the presence of multiple a. phagocytophilum strains has made it difficult to determine which reservoir hosts pose the greatest risk to humans and domestic animals. here we characterized three genetic markers (23s-5s rrna interge ...201121921109
zoonotic infections among employees from great smoky mountains and rocky mountain national parks, 2008-2009.u.s. national park service employees may have prolonged exposure to wildlife and arthropods, placing them at increased risk of infection with endemic zoonoses. to evaluate possible zoonotic risks present at both great smoky mountains (grsm) and rocky mountain (romo) national parks, we assessed park employees for baseline seroprevalence to specific zoonotic pathogens, followed by evaluation of incident infections over a 1-year study period. park personnel showed evidence of prior infection with a ...201222835153
zoonotic vector-borne bacterial pathogens in california mountain lions (puma concolor), 1987-2010.sera collected from 442 mountain lions in 48 california counties between the years of 1987 and 2010 were tested using immunofluorescence assays and agglutination tests for the presence of antibodies reactive to yersinia pestis, francisella tularensis, bartonella henselae, borrelia burgdorferi, and anaplasma phagocytophilum antigens. data were analyzed for spatial and temporal trends in seropositivity. seroprevalences for b. burgdorferi (19.9%) and b. henselae (37.1%) were relatively high, with t ...201222925024
temporal patterns of tick-borne granulocytic anaplasmosis in california.granulocytic anaplasmosis (ga) is a tick-borne emerging infectious disease caused by the bacterium anaplasma phagocytophilum. from fall 2005 to spring 2007, a. phagocytophilum infection prevalence in small mammals and tick abundance were monitored at 4 study sites in coastal california. the abundance of different life stages of questing ixodes pacificus ticks fluctuated seasonally with the number of adults peaking december to february, nymphs peaking may to july, and larvae peaking april to june ...201121771541
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
survey for zoonotic rickettsial pathogens in northern flying squirrels, glaucomys sabrinus, in california.epidemic typhus, caused by rickettsia prowazekii, is maintained in a southern flying squirrel (glaucomys volans) sylvatic cycle in the southeastern united states. the northern flying squirrel (glaucomys sabrinus) has not been previously associated with r. prowazekii transmission. a second rickettsial pathogen, anaplasma phagocytophilum, infects dusky-footed woodrats (neotoma fuscipes) and tree squirrels in northern california. because northern flying squirrels or their ectoparasites have not bee ...200717984264
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
reptile infection with anaplasma phagocytophilum, the causative agent of granulocytic anaplasmosis.granulocytic anaplasmosis (ga) is a potentially fatal tick-borne rickettsial disease that occurs sporadically in the far western united states. we evaluated the prevalence of anaplasma phagocytophilum in multiple species of lizards and snakes from enzootic sites in northern california, described the infestation prevalence of its tick vector ixodes pacificus on reptiles, and conducted an experimental challenge of western fence lizards (sceloporus occidentalis) and pacific gopher snakes (pituophis ...200919281295
differences in prevalence of borrelia burgdorferi and anaplasma spp. infection among host-seeking dermacentor occidentalis, ixodes pacificus, and ornithodoros coriaceus ticks in northwestern california.previous studies revealed that the pacific coast tick (dermacentor occidentalis) is infected occasionally with the agents of lyme disease (borrelia burgdorferi) or human granulocytic anaplasmosis (anaplasma phagocytophilum) and that it is an inefficient experimental vector of b. burgdorferi. the relationship of the pajahuello tick (ornithodoros coriaceus) to each of these bacterial zoonotic agents has not been reported. the primary bridging vector of both bacterial zoonotic agents to humans is t ...201021359090
ecology of anaplasma phagocytophilum infection in gray foxes (urocyon cinereoargenteus) in northwestern california.although granulocytic anaplasmosis, caused by infection of anaplasma phagocytophilum, is an emerging human and domestic animal disease, the ecology and natural history of the parasite is not well understood. gray foxes (urocyon cinereoargenteus) are relatively common, occasionally peri-urban mesocarnivores whose geographic distribution overlaps the reported distribution of granulocytic anaplasmosis in humans and domestic animals in north america. we evaluated the potential of foxes as hosts and ...200919395744
anaplasma phagocytophilum infection in small mammal hosts of ixodes ticks, western united states.a total of 2,121 small mammals in california were assessed for anaplasma phagocytophilum from 2006 through 2008. odds ratios were >1 for 4 sciurids species and dusky-footed woodrats. high seroprevalence was observed in northern sites. ten tick species were identified. heavily infested rodent species included meadow voles, woodrats, deer mice, and redwood chipmunks.200818598645
emergence of tick-borne granulocytic anaplasmosis associated with habitat type and forest change in northern california.an important ecosystem service of intact forests is protection from some emerging infectious diseases. tick-transmitted disease granulocytic anaplasmosis increasingly occupies second-growth forest. we hypothesized that areas of second growth would have increases in tick and rodent abundance, facilitating emergence of anaplasmosis. we predicted anaplasma phagocytophilum presence as a function of biocomplexity and forest structure, including vegetation, ticks, and rodents in four sites in californ ...200919996448
epidemiology and genetic diversity of anaplasma phagocytophilum in the san francisco bay area, california.in california, the agent of human granulocytic anaplasmosis (hga), anaplasma phagocytophilum, is transmitted by western black-legged ticks (ixodes pacificus). cases of hga are infrequent in california but do occur annually. we investigated nymphal and adult western black-legged tick populations in 20 recreational areas in california's san francisco bay area (marin, napa, san mateo, santa clara, santa cruz, and sonoma counties). overall, prevalence of a. phagocytophilum in adult ticks was 0.8% (1 ...201627139447
fine-scale genetic structure of woodrat populations (genus: neotoma) and the spatial distribution of their tick-borne pathogens.dusky-footed woodrats are territorial cricetid rodents that individually occupy large stick houses from which they foray to gather food, find mates, and engage in other activities. these rodents are often bitten by ixodes spp. ticks and are reservoirs of some strains of tick-borne bacterial pathogens such as anaplasma phagocytophilum and borrelia burgdorferi. limited dispersal by hosts and vectors could create fine-scale population structure where related hosts and pathogen exposure are co-distr ...201626530982
a real-time pcr assay for differentiating pathogenic anaplasma phagocytophilum from an apathogenic, woodrat-adapted genospecies from north america.anaplasma phagocytophilum is a tick-transmitted bacterial pathogen of humans and animals comprising strains that cause clinical disease in people, dogs and horses (the pathogenic a. phagocytophilum "genospecies") and more distantly related strains. a rodent-adapted genospecies named du1, found primarily in woodrats, is unable to infect horses. we developed a real-time pcr (rt-pcr) assay, which targets an 85 base pair region of the ank gene and is specific for the pathogenic genospecies of a. pha ...201526188998
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
nidicolous ticks of small mammals in anaplasma phagocytophilum-enzootic sites in northern california.ixodes spp. tick-borne zoonotic diseases are present across the holarctic in humans, domestic animals, and wildlife. small mammals are reservoirs for the rickettsial pathogen anaplasma phagocytophilum and tick vectors may include catholic-feeding bridge vectors as well as host-specialist or nidicolous ticks. far western north american communities in which a. phagocytophilum is maintained are complex ecologically, with multiple reservoir host and tick species, multiple strains of the bacterial pa ...201121686062
surveillance for ixodes pacificus and the tick-borne pathogens anaplasma phagocytophilum and borrelia burgdorferi in birds from california's inner coast range.we investigated the involvement of birds in the ecology of the western black-legged tick, ixodes pacificus, and its associated zoonotic bacteria, borrelia burgdorferi and anaplasma phagocytophilum, at two interior coast-range study sites in northern california. anaplasma phagocytophilum, the agent of granulocytic anaplasmosis (ga), and b. burgdorferi s.s., the agent of lyme disease (ld), are tick-borne pathogens that are well established in california. we screened blood and ticks from 349 indivi ...201424690191
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
prevalence of vector-borne bacterial pathogens in riparian brush rabbits (sylvilagus bachmani riparius) and their ticks.from june to october 2010, 48 endangered riparian brush rabbits (sylvilagus bachmani riparius) were trapped at a captive propagation site in central california with the intention of release into re-established habitats. during prerelease examinations, ticks and blood samples were collected for surveillance for rickettsia spp., anaplasma phagocytophilum, borrelia burgdorferi, and bartonella spp. ticks were identified, and dna was extracted for pcr analysis. serology was performed to detect exposu ...201424506421
detection of anaplasma phagocytophilum in ixodid ticks from equine-inhabited sites in the southeastern united states.abstract anaplasma phagocytophilum is a vector-borne, obligate intracellular bacterium that invades the neutrophils and eosinophils of infected individuals, causing granulocytic anaplasmosis. equine cases have previously been reported in the united states from california, florida, and connecticut, but limited surveillance studies in the southeast have been conducted. the objective of this study was to determine a. phagocytophilum prevalence in ixodes scapularis ticks at southeastern u.s. horse ...201222214269
evaluation of anaplasma phagocytophilum infection in experimentally inoculated sheep and determination of anaplasma spp seroprevalence in 8 free-ranging sheep flocks in california and oregon.to evaluate disease progression in sheep experimentally inoculated with anaplasma phagocytophilum and determine the anaplasma spp seroprevalence in sheep in free-ranging flocks in the sierra nevada foothills and oregon coast range.201222738055
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
pathogen and rodenticide exposure in american badgers (taxidea taxus) in california.urban and agricultural land use may increase the risk of disease transmission among wildlife, domestic animals, and humans as we share ever-shrinking and fragmented habitat. american badgers (taxidae taxus), a species of special concern in california, usa, live in proximity to urban development and often share habitat with livestock and small peridomestic mammals. as such, they may be susceptible to pathogens commonly transmitted at this interface and to anticoagulant rodenticides used to contro ...201222493124
evaluation of squirrels (rodentia: sciuridae) as ecologically significant hosts for anaplasma phagocytophilum in california.granulocytic anaplasmosis (ga), caused by anaplasma phagocytophilum, is a potentially fatal, emerging rickettsial disease of humans, domestic animals, and wildlife. the purpose of this study was to determine whether sciurids from multiple areas of northern california were infested with ticks or exposed to or infected with a. phagocytophilum using polymerase chain reaction (pcr) and indirect-fluorescent antibody (ifa) serology. sciurids of nine different tree- and ground-dwelling species were ass ...200818714881
vector biodiversity did not associate with tick-borne pathogen prevalence in small mammal communities in northern and central california.vector and host abundance affect infection transmission rates, prevalence, and persistence in communities. biological diversity in hosts and vectors may provide "rescue" hosts which buffer against pathogen extinction and "dilution" hosts which reduce the force of infection in communities. anaplasma phagocytophilum is a tick-transmitted zoonotic pathogen that circulates in small mammal and tick communities characterized by varying levels of biological diversity. we examined the prevalence of a. p ...201424582513
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
reservoir competence of the redwood chipmunk (tamias ochrogenys) for anaplasma phagocytophilum.granulocytic anaplasmosis (ga) is an emerging tick-transmitted disease that persists in rodent- ixodes ricinus-complex tick cycles across the holarctic. although the putative reservoir for anaplasmosis in the western united states is the dusky-footed woodrat (neotoma fuscipes), this rodent was not shown reservoir-competent because of failure of infection from woodrats to other animals via ticks. redwood chipmunks are common in habitats where anaplasma phagocytophilum is common, have high pcr- an ...200919327022
gray foxes (urocyon cinereoargenteus) as a potential reservoir of a bartonella clarridgeiae-like bacterium and domestic dogs as part of a sentinel system for surveillance of zoonotic arthropod-borne pathogens in northern california.two species of bartonella, a novel bartonella clarridgeiae-like bacterium and b. vinsonii subsp. berkhoffii, were isolated from rural dogs and gray foxes in northern california. a novel b. clarridgeiae-like species was isolated from 3 (1.7%) of 182 dogs and 22 (42%) of 53 gray foxes, while b. vinsonii subsp. berkhoffii was isolated from 1 dog (0.5%) and 5 gray foxes (9.4%). pcr and dna sequence analyses of the citrate synthase (glta) gene and the 16s-23s intergenic spacer region suggested that s ...200717553970
differential exposure to anaplasma phagocytophilum in rodent species in northern california.anaplasma phagocytophilum is a zoonotic tick-borne rickettsial pathogen that causes granulocytic anaplasmosis (ga) in humans, horses, and dogs. in california, dusky-footed woodrats (neotoma fuscipes) are a putative reservoir host, and ixodes pacificus is a vector for transmission from rodents to humans, dogs, and horses. cases are clustered in coastal and sierra nevada foothill regions, but not necessarily in proximity to infected woodrats. this study was designed to compare exposures and active ...200818047398
unique strains of anaplasma phagocytophilum segregate among diverse questing and non-questing ixodes tick species in the western united states.the emerging tick-borne pathogen anaplasma phagocytophilum infects humans, domestic animals, and wildlife throughout the holarctic. in the western us, the ecology of a. phagocytophilum is particularly complex, with multiple pathogen strains, tick vectors, and reservoir hosts. a recent phylogenetic analysis of a. phagocytophilum strains isolated from various small mammal hosts in california documented distinct clustering of woodrat strains separate from sciurid (chipmunk and squirrel) strains. he ...201323994335
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