distribution of suspected tick vectors and reported cases of rocky mountain spotted fever in california.evidence is presented for an area of human risk to rocky mountain spotted fever (rmsf) in california extending beyond the range of its classic tick vector, dermacentor andersoni. geographic, seasonal, and host distributions of dermacentor variabilis and dermacentor occidentalis suggest these species as potential vectors of rmsf in california outside the range of dermacentor andersoni.1976961695
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
parasitic and phoretic arthropods of the elephant-eared and the santa cruz kangaroo rats.the parasitic and phoretic arthropods of the elephant-eared kangaroo rat (dipodomys elephantinus) and santa cruz kangaroo rat (d. venustus) are reported; most of these represent new host records. thirteen of 14 (93%) of d. elephantinus and 11 of 12 (92%) of d. venustus had 11 and nine arthropod species, respectively. larval and nymphal stages of the tick dermacentor occidentalis were the most prevalent parasite (77%) on d. elephantinus whereas the mesostigmatid mite androlaelaps fahrenholzi was ...19912067062
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
spirochetes in mammals and ticks (acari: ixodidae) from a focus of lyme borreliosis in northern california, antibodies to borrelia burgdorferi were detected in 58 of 73 (79%), and spirochetemias in one of 26 (4%) black-tailed jackrabbits (lepus californicus californicus), by indirect and direct immunofluorescence, respectively. five species of ticks (dermacentor occidentalis, d. parumapertus, ixodes neotomae, i. pacificus, and haemaphysalis leporispalustris) were collected from rabbits. two of these species of ticks were found to contain spirochetes; two of 10 (20%) i. neotomae ...19883280837
diurnal host seeking of adult pacific coast ticks, dermacentor occidentalis (acari: ixodidae), in relation to vegetational type, meteorological factors, and rickettsial infection rates in california, usa. 19853930742
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
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
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
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
ixodid ticks (acari, ixodidae) found in san diego county, san diego county, california, 11 species of ixodid ticks were collected from vegetation and/or from small and large mammals, and/or found parasitizing humans. adults of the pacific coast tick, dermacentor occidentalis, were the most abundant tick collected from vegetation, with peak numbers occurring during march and april. adults of the western black-legged tick, ixodes pacificus, were the second most abundant, with peaks occurring during february and march. eight species of ticks were found ...199910436879
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
anti-arthropod saliva antibodies among residents of a community at high risk for lyme disease in california.the role of the western black-legged tick (ixodes pacificus) versus that of other potential arthropod vectors in the epidemiology of lyme disease was evaluated by determining the prevalence of anti-arthropod saliva antibodies (aasa) among residents (n = 104) of a community at high-risk (chr). salivary gland extracts prepared from i. pacificus, the pacific coast tick (dermacentor occidentalis), the western cone-nose bug (triatoma protracta), and the western tree-hole mosquito (aedes sierrensis) w ...199910586924
description and epidemiology of theileria youngi n. sp. from a northern californian dusky-footed woodrat (neotoma fuscipes) epidemiologic study designed to identify the small mammal reservoir for the zoonotic wa1-type babesial parasite resulted in the discovery of a small, intraerythrocytic piroplasm in smeared blood from dusky-footed woodrats (neotoma fuscipes) in northern california. the woodrat parasites were isolated and compared to other piroplasm parasites based on their morphology, antigenicity, and genetic characteristics. these studies indicated that the woodrat parasites were not the wa1-type babesial ag ...200111318567
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
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
the roles of birds, lizards, and rodents as hosts for the western black-legged tick ixodes pacificus.we compared the infestation by ixodid ticks of lizards, rodents, and birds collected simultaneously within areas representing common habitat types in mendocino county, ca. lizards were infested only by ixodes pacificus cooley and kohls, birds by i. pacificus and haemaphysalis leporispalustris (packard), and rodents by i. pacificus, i. spinipalpis hadwen and nuttall, i. woodi bishopp, dermacentor occidentalis marx, and d. variabilis (say). infestation by i. pacificus larvae and nymphs of lizards ...200415709249
columbian black-tailed deer (odocoileus hemionus columbianus) as hosts for borrelia spp. in northern california.the prevalence of infection of columbian black-tailed deer (odocoileus hemionus columbianus) with borrelia spp. was evaluated in an area of northwestern california (usa) where lyme disease is endemic and the relapsing-fever group spirochete borrelia coriaceae is enzootic, and in a far-removed comparison area having a disparate climate and lower density of vector ticks. blood samples collected from both deer herds in 1987, 1988, and from 2000-02 were assayed for borrelial infection with microscop ...200515827217
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
geographical distribution patterns and habitat suitability models for presence of host-seeking ixodid ticks in dense woodlands of mendocino county, california.we used drag sampling to examine the geographical distribution patterns of ixodid ticks engaging in open (non-nidicolous) host-seeking behavior in dense woodland habitats of the climatically and ecologically diverse mendocino county in north coastal california. the findings based on this sampling methodology reflect risk of human exposure to host-seeking ticks rather than the true distribution of the ticks. drag sampling in 78 sites yielded 7,860 nymphal or adult ixodes pacificus cooley & kohls, ...200616619628
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
detection and identification of spotted fever group rickettsiae in dermacentor species from southern california.dermacentor occidentalis marx and dermacentor variabilis (say) commonly bite humans in california. these dermacentor species may play a role in transmitting spotted fever group (sfg) rickettsiae to humans in many parts of the state where dermacentor andersoni stiles, a known vector for the etiologic agent of rocky mountain spotted fever, rickettsia rickettsii, is absent. however, the specific rickettsial agents present in these ticks and their current prevalence are poorly understood. in total, ...200818533446
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
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
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
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
rickettsia 364d: a newly recognized cause of eschar-associated illness in california.four spotted fever group rickettsiae (sfgr) are known to infect humans in the united states. a member of the sfgr designated 364d and detected in dermacentor occidentalis ticks has not previously been identified as a human pathogen.201020073993
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