Publications

TitleAbstractYear
Filter
PMID
Filter
bovine anaplasmosis transmission studies conducted under controlled natural exposure in a dermacentor andersoni = (venustus) indigenous area of eastern oregon.in anaplasma marginale transmission studies conducted on the high semi-arid range of eastern oregon during the 1974 and 1975 vector season, a marginale-susceptible calves (principals) were maintained on 2 raised tick-proof platforms. anaplasmosis-susceptible control calves of approximately the same age and latent-infected cows grazed the area surrounding the platforms. one latent-infected steer spent the entire 1975 vector season on a platform with the principals. the 28 principals did not devel ...1977557939
evaluation of free-roaming mule deer as carriers of anaplasmosis in an area of idaho where bovine anaplasmosis is enzootic.samples of blood from 87 rocky mountain mule deer (odocoileus hemionus hemionus) were inoculated into 3 susceptible splenectomized calves to determine the anaplasmosis carrier status of the deer. the deer were trapped along the idaho-utah state boundary, near stone, id. acute anaplasmosis was induced in 2 of the 3 inoculated calves, and blood from the 3 calves caused anaplasmosis when inoculated into adult non-splenectomized cattle. serum rapid card agglutination testing revealed 13 (14.9%) posi ...1977833034
failure of anaplasma marginale theiler to survive natural winter conditions on a dermacentor andersoni = (venustus) infested range. 19761078097
absence of anaplasma marginale infection in american bison raised in an anaplasmosis endemic area.blood was collected at slaughter from 132 adult american bison (bison bison) raised in an anaplasmosis endemic area where the vector dermacentor andersoni (equals venustus) is indigenous. hematologic studies revealed no indication of clinical anaplasmosis. card agglutination and complement-fixation tests on all bison serums were negative. eleven anaplasmosis-susceptible calves each inoculated with 204 ml of blood pooled from 12 bison did not develop anaplasmosis. results of this study indicate a ...19751152178
persistence of anaplasma marginale (rickettsiales: anaplasmataceae) in male dermacentor andersoni (acari: ixodidae) transferred successively from infected to susceptible calves.the persistence of anaplasma marginale theiler in male dermacentor andersoni stiles ticks exposed to the organism as adults was studied as the ticks were successively transferred to five susceptible calves. all calves fed upon by these ticks rapidly developed clinical anaplasmosis; incubation periods of infection ranged from 19 to 26 d and did not change significantly with successive feedings. development of a. marginale in tick midgut and salivary glands was followed daily during tick feeding ( ...19921495076
development of anaplasma marginale in male dermacentor andersoni transferred from parasitemic to susceptible cattle.the development and transmission of anaplasma marginale was studied in dermacentor andersoni males. laboratory-reared male d andersoni were allowed to feed for 7 days on a calf with ascending a marginale parasitemia. the ticks were then held in a humidity chamber for 7 days before being placed on 2 susceptible calves. anaplasmosis developed in the calves after incubation periods of 24 and 26 days. gut and salivary glands were collected from ticks on each day of the 23-day experiment and examined ...19921586018
intermediate site of development of anaplasma marginale in feeding adult dermacentor andersoni ticks that were infected as nymphs.the development of anaplasma marginale in midgut epithelial cells was studied in feeding, transmitting adult dermacentor andersoni ticks. laboratory-reared ticks experimentally infected as nymphs were allowed to feed from 1 to 9 days on susceptible calves. gut tissues from ticks were collected on each day they fed (total, 9 days) and were processed for light and transmission electron microscopy. colonies of a marginale were abundant during the first 6 days of feeding, after which numbers decreas ...19902301812
development and infectivity of anaplasma marginale in dermacentor andersoni nymphs.the development of anaplasma marginale was studied in dermacentor andersoni nymphs after they had fed on a calf with ascending anaplasma infection. gut tissues were collected on day 4 of tick feeding, from newly replete (fed) nymphs and on postfeeding days (pfd) 5, 10, 15, 20, and were processed for light and electron microscopy to determine density of a marginale colonies. homogenates of gut tissues were prepared from nymphs collected on the same days and inoculated into susceptible, splenectom ...19902386330
presence of common antigens, including major surface protein epitopes, between the cattle (intraerythrocytic) and tick stages of anaplasma marginale.epitopes of major surface proteins of the intraerythrocytic cattle stage of anaplasma marginale were demonstrated in the midgut stage of the organism within the infective tick host dermacentor andersoni. these proteins were common to all a. marginale isolates tested and at all stages of parasitemia. sera from cattle immunized with the tick midgut stage of a. marginale immunoprecipitated multiple-erythrocyte-stage proteins, as demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophore ...19852415457
preliminary studies of the development of anaplasma marginale in salivary glands of adult, feeding dermacentor andersoni ticks.on each day of feeding on susceptible calves, salivary glands obtained from groups of adult ticks that transmitted anaplasma marginale were examined for a marginale colonies by use of light microscopy and transmission electron microscopy. on day 8 of feeding, salivary glands were examined, using fluorescein-labeled antibody and methyl green-pyronine stain. use of fluorescein-labeled antibody consistently revealed small numbers of fluorescent foci in salivary gland acinar cells obtained from tick ...19882458688
hybridization of dna probes to a. marginale isolates from different sources and detection in dermacentor andersoni ticks.dna from the washington, south-idaho, virginia and florida isolates of anaplasma marginale was hybridized to probes specific for anaplasma centrale and a. marginale. the a. centrale probes ac-2 and ac-4 hybridized to identical bands on all of these isolates. the hybridization patterns suggests that the virginia, florida and the south african isolates are similar. a number of bands were obtained with the washington isolate which differed from those obtained with the other isolates. probe ac-2 cou ...19883217095
attempted transmission to cattle of anaplasma marginale from overwintered dermacentor andersoni ticks.since the 1983 summer outbreak of anaplasmosis in southern saskatchewan, the role of the tick, dermacentor andersoni as an overwintering reservoir for anaplasma marginale has been questioned. the purpose of this study was to determine if spring-collected ticks carried virulent a. marginale. sixteen splenectomized calves were assigned randomly to two groups of 14 principals and two controls. adult d. andersoni, collected in april from areas having high transmission rates of a. marginale, were con ...19873651893
longevity of colonies of anaplasma marginale in midgut epithelial cells of dermacentor andersoni.colonies of anaplasma marginale in midgut epithelial cells of experimentally infected dermacentor andersoni were studied in adult ticks 1, 3, and 6 months old. longevity of the parasite in ticks was assessed by evaluating its infectivity for splenectomized calves; calves were exposed by feeding ticks and by inoculation of tick gut homogenates. longevity was also evaluated by determining size, type, and density of colonies in male and female ticks. the effect of incubation (2.5 days at 37 c) on c ...19863752671
percutaneous infection of nymphal dermacentor andersoni with anaplasma marginale.newly replete nymphal dermacentor andersoni (principals) were percutaneously exposed to anaplasma marginale by injection of either intact or lysed infected bovine erythrocytes. control nymphs were fed on calves with anaplasmosis. the subsequently molted adults were examined for infection by light microscopy, and companion ticks were tested for infectivity by allowing them to feed on susceptible calves. when they fed as adults, both control ticks and percutaneously inoculated principals transmitt ...19863752672
transmission of anaplasma marginale theiler by males of dermacentor andersoni stiles fed on an idaho field-infected, chronic carrier cow.the role of ticks and carrier cattle in epizootics of bovine anaplasmosis was further clarified by demonstrating unequivocally, for the first time, that male ticks fed on a chronic carrier cow naturally infected with anaplasma marginale can transmit this parasite intrastadially and biologically when subsequently fed on susceptible cattle. these data indicate that field epizootics of acute anaplasmosis may be initiated by males of tick vector species that feed on carrier cattle and subsequently t ...19863777655
infectivity of three anaplasma marginale isolates for dermacentor andersoni.three isolates of anaplasma marginale--virginia (vam), illinois (iam), and florida (fam)--were compared for infectivity for dermacentor andersoni. the isolates were selected, in part, because of a tail-like appendage that has been demonstrated in the vam and iam, but not in the fam. ticks were exposed to the isolates as nymphs either naturally by feeding on a calf with anaplasmosis or artificially by percutaneous inoculation with infected bovine erythrocytes. they were examined for infectivity a ...19873826850
epidemiologic aspects of bovine anaplasmosis in semiarid range conditions of south central idaho.the prevalance of anaplasma marginale-infected cows, as determined by use of the modified rapid card agglutination (mrca) test, was measured during a 4-year period (1980-1983). the prevalence of a marginale-infected cows, defined as positive reactors on the mrca test, remained constant (31%-37%). the apparent incidence of a marginale transmission to susceptible cows was approximately 7% from 1980 to 1981, 8% from 1981 to 1982, and no transmission from 1982 to 1983. the occasional mrca-positive c ...19863963555
transmission of anaplasma marginale by adult dermacentor andersoni during feeding on calves.laboratory-reared dermacentor andersoni ticks experimentally infected as nymphs with anaplasma marginale were allowed to feed as adults from 1 to 9 days on susceptible, splenectomized calves to determine when, during feeding, the hematozoan was transmitted from ticks to cattle. in experiment 1, ticks were allowed to feed on calves for 1, 2, 3, 4, 5, or 6 days and anaplasmosis did not result. the same calves were used for experiment 2, and ticks were allowed to feed for 1, 3, 6, 7, 8, or 9 days a ...19854026042
recognition of anaplasma marginale theiler in dermacentor andersoni stiles (=d. venustus marx) by the fluorescent antibody method. i. smears of nymphal organs. 19704189907
transstadial (nymph-to-adult) infection of anaplasma marginale in dermacentor andersoni stiles. 19715160254
anaplasmosis. xix. a preliminary study of anaplasma marginale in dermacentor andersoni (stiles) by fluorescent antibody technique. 19665335865
staining characteristics of colonies of anaplasma marginale theiler in dermacentor andersoni stiles.colonies of anaplasma marginale theiler were studied in midgut epithelial cells of adult dermacentor andersoni stiles that were infected as nymphs. the colonies were demonstrated in plastic sections (1 micrometer) and frozen sections (6 micrometer) with mallory's stain. colonies were also demonstrated in frozen sections, using direct fluorescent antibody technique. colonies were not observed in plastic or frozen sections stained by the giménez method. in all preparations, the colonies were usual ...19816175257
immunocytochemical labeling of anaplasma marginale theiler in dermacentor andersoni stiles with peroxidase- antiperoxidase technique.colonies of anaplasma marginale in midgut epithelial cells of adult ticks that had been infected as nymphs were specifically labeled, using the unlabeled antibody peroxidase-antiperoxidase method of immunocytochemistry. visual comparison of infected and control tissue sections with the electron microscope demonstrated deposition of ring-like peroxidase-antiperoxidase complexes over organisms within the colonies. the intensity of labeling differed among organisms within a single colony, possibly ...19826285774
demonstration of anaplasma marginale in hemolymph of dermacentor andersoni by animal inoculation and by fluorescent-antibody technique.hemolymph was collected from adult dermacentor andersoni stiles that had been infected with anaplasma marginale theiler as nymphs. before hemolymph was collected, the adult ticks were either incubated and unfed at 37 c for 2.5 days or fed for 6 days on sheep. hemolymph collected from groups of 100 ticks was inoculated into susceptible splenectomized calves. smears of hemolymph from the same groups of ticks were prepared for examination by fluorescent antibody technique. hemolymph from incubated ...19836346968
demonstration of the inclusion appendage of anaplasma marginale in nymphal dermacentor andersoni.dermacentor andersoni nymphs were placed in stockinettes and allowed to feed on a splenectomized calf with experimentally induced anaplasmosis when the parasitemia was 3%-5%. nymphs were selected on each of the 6 days of feeding and every 5 days from repletion through molting to the adult stage (25 days postrepletion); they were killed and midgut tissues were processed and examined by light and electron microscopies. no stages of a marginale were seen in tissues of feeding ticks. visualization o ...19846497136
development of colonies of anaplasma marginale in the gut of incubated dermacentor andersoni. 19836625314
demonstration of colonies of anaplasma marginale in the midgut of rhipicephalus simus.rhipicephalus simus nymphs were allowed to feed on a cow experimentally infected with the bw-strain of anaplasma marginale from republic of south africa, and they were studied as adults. colonies were demonstrated by light microscopy in midgut epithelial cells of adult ticks that were unfed (as adults), incubated, or prefed for 72 hours on a cow. the colonies occurred in 5 different morphologic types (1 to 5) that were similar to those described previously for a virginia isolate of a marginale i ...19836660614
influence of parasitemia level at feeding on development of anaplasma marginale theiler in dermacentor andersoni stiles.four splenectomized dairy calves were inoculated with a virginia isolate of anaplasma marginale theiler and served as an infective source (donor) for laboratory-reared dermacentor andersoni stiles nymphs. two donor calves developed higher parasitemias during tick feeding than did the 2 other donor calves. one month after molting, adult ticks were incubated at 37 c for 2.5 days to stimulate development of colonies of a marginale, and homogenates of gut were made from ticks fed on each donor calf. ...19836869951
demonstration of anaplasma marginale theiler in ticks by tick transmission, animal inoculation, and fluorescent antibody studies.cattle were inoculated with a virginia isolate of anaplasma marginale theiler and served as an infective source for laboratory-reared dermacentor andersoni stiles and d variabilis (say) nymphs. transstadial transmission of a marginale was demonstrated by feeding the newly molted adult ticks of both species on susceptible cattle and by inoculation of gut and salivary gland homogenates collected from adult ticks at postattachment days 5 and 7. oral secretions collected from the same group of ticks ...19806989298
morphologic characteristics of colonies of anaplasma marginale theiler in midgut epithelial cells of dermacentor andersoni stiles.colonies of anaplasma marginale theiler were studied in midgut epithelial cells of adult dermacentor andersoni stiles that were infected as nymphs. colonies were categorized by light microscopy into 5 morphologic types that appear to represent stages in a developmental sequence. the mean diameter of the colony types ranged from 5.64 micrometer to type 1 colonies to 10.49 micrometers of type 5 colonies. representatives of each colony type were selected by light microscopy and were sectioned for e ...19827073078
influence of increased temperature on anaplasma marginale theiler in the gut of dermacentor andersoni stiles.three splenectomized dairy calves were inoculated with a virginia isolate of anaplasma marginale theiler and served as an infective source for laboratory-reared dermacentor andersoni stiles nymphs. one month after molting, groups of adult ticks were incubated at 37 c for 0, 1.5, 2.5, and 7 days. gut homogenates were made from ticks representing each incubation period. twenty-four susceptible, splenectomized dairy calves were each inoculated iv with a gut homogenate extracted from 50 adult ticks ...19827091815
ultrastructure of anaplasma marginale theiler in dermacentor andersoni stiles and dermacentor variabilis (say).cattle were inoculated with a virginia isolate of anaplasma marginale theiler and served as an infective source for laboratory-reared dermacentor andersoni stiles and d variabilis (say) nymphs. anaplasma marginale was demonstrated by electron microscopy in gut tissues of replete nymphal ticks and in unfed, incubated, and feeding adult ticks that were exposed to the organism as nymphs when they fed on an infected cow. the a marginale organism in replete nymphs and adult feeding ticks were morphol ...19807212430
transmission of anaplasma marginale theiler by dermacentor andersoni stiles and dermacentor variabilis (say).cattle were inoculated with a virginia isolate of anaplasma marginale theiler and served as an infective source for laboratory-reared dermacentor andersoni stiles and d variabilis (say) nymphs. following a molt and subsequent feeding of adult ticks on susceptible cows, transstadial transmission of a marginale occurred from cattle with parasitemias ranging from undetectable (in a carrier cow) to a peak of 27% (in an acutely ill cow). homogenates of gut tissue from unfed, incubated, and feeding ad ...19817224310
chemoprophylaxis of vector-borne anaplasmosis with sustained-release boluses.sustained-release oxytetracycline boluses (20%) delivering 145 to 150 mg/bolus/day were administered to complement-fixation test-negative cattle at dosages of 2.0, 2.5, and 3.0 mg/kg of body weight. subsequent challenge exposure of cattle with dermacentor andersoni stiles infected with anaplasma marginale theiler indicated that treatment with the dosage of 2.5 mg/kg prevented clinical anaplasmosis and that treatment with the dosage of 3.0 mg/kg prevented disease infection.19817340579
molecular and biological characterization of a newly isolated anaplasma marginale strain.anaplasma marginale, a rickettsial hemoparasite of cattle and other ruminants, results in significant economic losses worldwide. distinct strains of a. marginale have been identified based on differences in tick transmissibility, molecular size of surface proteins and dna restriction fragments, and reactivity to a panel of monoclonal antibodies. these different strains vary considerably in their virulence, antigenic composition, and ability to protect against heterologous challenge. in this pape ...19947858023
persistence of tick-derived anaplasma marginale in cultured bovine turbinate and endothelial cells.anaplasma marginale from salivary glands of dermacentor andersoni was used to inoculate monolayers of bovine turbinate and endothelial cells. monolayers were passaged at 2 or 4 week intervals and monitored with light and electron microscopy and with an a. marginale-specific dna probe. intracellular inclusions were observed in turbinate cells after 2-4 weeks. the number of inclusion-bearing cells increased over 1-2 weeks and gradually disappeared. a radiolabeled fragment from within the msp1 beta ...19938134656
detection of anaplasma marginale (rickettsiales: anaplasmataceae) in hemolymph of dermacentor andersoni (acari: ixodidae) with the polymerase chain reaction.the polymerase chain reaction (pcr) was used to detect anaplasma marginale in hemolymph collected from live dermacentor andersoni stiles ticks. hemolymph was collected from severed legs of male and female ticks exposed to a. marginale as either nymphs or adults. heat treatment was found to be the optimum method of hemolymph preparation for pcr. hemolymph samples were collected and pooled from adult ticks exposed as nymphs on days 0-10 of feeding on a susceptible calf. for male and female ticks e ...19938360902
detection of anaplasma marginale (rickettsiales: anaplasmataceae) in secretagogue-induced oral secretions of dermacentor andersoni (acari: ixodidae) with the polymerase chain reaction.the polymerase chain reaction (pcr) was used to detect anaplasma marginale in secretagogue-induced oral secretions of male and female dermacentor andersoni stiles exposed as nymphs or adults by feeding on infected calves. a 409-bp dna fragment derived from the a. marginale (florida isolate) msp1 beta gene was amplified with oligonucleotide primers bap-2 (5'-gtatggcacgtagtcttgggatca-3') and al34s (5'-cagcagcagcaagaccttca-3'). the target dna was amplified in oral secretions of female ticks exposed ...19938360903
impact of persistent anaplasma marginale rickettsemia on tick infection and transmission.anaplasma marginale, an intraerythrocytic rickettsia of cattle, is transmitted biologically by ticks. because of the brevity of acute a. marginale infection, transmission may rely on the tick's ability to acquire the organism from persistently infected cattle with low rickettsemia levels. by using a nucleic acid probe to quantitate low-level infection, we found that rickettsemia levels in persistently infected cattle fluctuated at approximately 5-week intervals during a 24-week period, from < 10 ...19938370734
development of anaplasma marginale in salivary glands of male dermacentor andersoni.development of the rickettsia, anaplasma marginale, in salivary glands of male dermacentor andersoni exposed as nymphs or adult ticks, was studied indirectly by inoculation of susceptible calves with homogenates and directly by examination, using light microscopy and a dna probe; some unfed ticks were incubated before tissues were collected. salivary gland homogenates made from ticks in every treatment group caused anaplasmosis when injected into susceptible calves; prepatent periods decreased a ...19938427453
preliminary studies on the effect of anaplasma marginale antibodies ingested by dermacentor andersoni ticks (acari:ixodidae) with their blood meal on infections in salivary glands.the effect of anaplasma marginale antibodies ingested with the tick blood meal was tested on infected male ticks that were allowed to feed on cattle immunized with the erythrocytic stage of a. marginale. the experiments were done in two trials. trial 1 was done using splenectomized calves (two calves per treated and control groups) while ticks in trial 2 were fed on intact yearling cattle (four cattle per treated and control groups). the cattle were immunized with purified outer membrane protein ...19968674360
antibody against an anaplasma marginale msp5 epitope common to tick and erythrocyte stages identifies persistently infected cattle.a protein epitope of major surface protein 5 (msp5), defined by monoclonal antibody (mab) anaf16c1, is conserved among anaplasma species (e. s. visser, t. c. mcguire, g. h. palmer, w. c. davis, v. shkap, e. pipano, and d. p. knowles, jr., infect. immun. 60:5139-5144, 1992) and is expressed in the salivary glands of infected ticks. a competitive inhibition elisa (celisa) for the detection of bovine anti-msp5 antibodies was developed by using purified recombinant msp5 fusion protein and mab anaf16 ...19968862589
developmental studies of anaplasma marginale (rickettsiales:anaplasmataceae) in male dermacentor andersoni (acari:ixodidae) infected as adults by using nonradioactive in situ hybridization and microscopy.the development of anaplasma marginale theiler was studied in ticks using a nonradioactive in situ hybridization method developed in our laboratory. male rocky mountain wood ticks, dermacentor andersoni stiles, were infected intrastadially by allowing them to feed for 7 d on an infected calf (acquisition feeding). the ticks were then removed and held in a humidity chamber for 5 d before being fed on a 2nd susceptible call for 10 d (transmission feeding). two groups of 10 ticks were collected dai ...19968961639
development of a non-radioactive dna probe and in situ hybridization for detection of anaplasma marginale in ticks and cattle.a non-radioactive dna probe was developed for detection of anaplasma marginale in ticks and cattle. the probe was labeled with digoxigenin 11-dutp by polymerase chain reaction. the probe was tested on bovine blood and was found to be a sensitive and specific detection method for a. marginale in cattle. the dna probe was then adapted for in situ hybridization (ish) of a. marginale in dermacentor andersoni and d. variabilis ticks infected either as nymphs or adults. one-half of each tick was studi ...19989668458
strain diversity in major surface protein 2 expression during tick transmission of anaplasma marginale.specific major surface protein 2 (msp2) variants are expressed by anaplasma marginale within the tick salivary gland and, following transmission, are expressed during acute rickettsemia. in previous work, we have shown that a restricted pattern of msp2 variants is expressed in the salivary glands of dermacentor andersoni ticks infected with the south idaho strain of a. marginale. now we demonstrate that the identical restriction does not apply to two other strains of a. marginale, and that diffe ...200010769008
strain composition of the ehrlichia anaplasma marginale within persistently infected cattle, a mammalian reservoir for tick transmission.tick-borne ehrlichial pathogens of animals and humans require a mammalian reservoir of infection from which ticks acquire the organism for subsequent transmission. in the present study, we examined the strain structure of anaplasma marginale, a genogroup ii ehrlichial pathogen, in both an acute outbreak and in persistently infected cattle that serve as a reservoir for tick transmission. using the msp1alpha genotype as a stable strain marker, only a single genotype was detected in a disease outbr ...200111158120
health protocol for translocation of free-ranging elk.when considering an elk (cervus elaphus) restoration program, wildlife managers must evaluate the positive and negative elements of translocation. we prepared this protocol to give an overview of health considerations associated with translocation of elk, with an emphasis on movement of free-ranging elk from western north america to the southeastern usa. we evaluated infectious agents and ectoparasites reported in elk from two perspectives. first, we made a qualitative estimate of the ability of ...200111504216
specific expression of anaplasma marginale major surface protein 2 salivary gland variants occurs in the midgut and is an early event during tick transmission.infectivity of anaplasma spp. develops when infected ticks feed on a mammalian host (transmission feed). specific anaplasma marginale major surface protein 2 (msp2) variants are selected for within the tick and are expressed within the salivary glands. the aims of this study were to determine when and where msp2 variant selection occurs in the tick, how msp2 expression is regulated in salivary glands of transmission-feeding ticks, and whether the number of a. marginale organisms per salivary gla ...200211748171
transmission of anaplasma marginale by boophilus microplus: retention of vector competence in the absence of vector-pathogen interaction.whether arthropod vectors retain competence for transmission of infectious agents in the long-term absence of vector-pathogen interaction is unknown. we addressed this question by quantifying the vector competence of two tick vectors, with mutually exclusive tropical- versus temperate-region distributions, for genetically distinct tropical- and temperate-region strains of the cattle pathogen anaplasma marginale. the tropical cattle tick boophilus microplus, which has been eradicated from the con ...200312904396
anaplasma marginale theiler observed in the gut and excreta of dermacentor andersoni stiles (dermacentor venustus marx). 196414204828
variation among geographically separated populations of dermacentor andersoni (acari: ixodidae) in midgut susceptibility to anaplasma marginale (rickettsiales: anaplasmataceae).anaplasma marginale is a tick-borne rickettsial pathogen of cattle that is endemic throughout large areas of the united states. cattle that survive acute infection become life-long persistently infected carriers. in the intermountain west the rocky mountain wood tick, dermacentor andersoni stiles, is the most common vector of a. marginale. male d. andersoni acquire a. marginale when feeding on persistently infected cattle and biologically transmit it when they transfer from infected to susceptib ...200515799524
relative efficiency of biological transmission of anaplasma marginale (rickettsiales: anaplasmataceae) by dermacentor andersoni (acari: ixodidae) compared with mechanical transmission by stomoxys calcitrans (diptera: muscidae).anaplasma marginale theiler is a tick-borne intraerythrocytic rickettsial pathogen of cattle that also can be mechanically transmitted by biting flies. rickettsemia during the acute phase of infection may reach as high as 10(9) infected erythrocytes (ies) per milliliter of blood. animals that survive acute infection develop a life-long persistent infection that cycles between 10(2.5) and 10(7) ie/ ml of blood. we compared stable fly stomoxys calcitrans (l.) -borne mechanical transmission during ...200516119558
distribution, seasonality, and hosts of the rocky mountain wood tick in the united states.anaplasma marginale theiler is a tick-borne pathogen that causes anaplasmosis in cattle. there are approximately 20 tick species worldwide that are implicated as vectors of this pathogen. in the united states, dermacentor andersoni stiles and dermacentor variabilis (say) are the principal vectors. the risk of transmission of anaplasmosis to cattle has been largely based on the distribution of d. andersoni in the united states. we developed a centralized geographic database that incorporates coll ...200616506443
a canadian bison isolate of anaplasma marginale (rickettsiales: anaplasmataceae) is not transmissible by dermacentor andersoni (acari: ixodidae), whereas ticks from two canadian d. andersoni populations are competent vectors of a u.s. strain.anaplasma marginale theiler is a tick-borne rickettsial pathogen of cattle with a global distribution in both temperate and tropical regions. the pathogen is endemic in regions within the united states, whereas the canadian cattle population is considered to be free ofa. marginale. farmed bison, bison bison l., in central saskatchewan have been found to be infected with a. marginale; however, there is no evidence of transmission from bison to cattle. we tested a saskatchewan bison isolate of a. ...200617017236
transcriptome analysis of the salivary glands of dermacentor andersoni stiles (acari: ixodidae).amongst blood-feeding arthropods, ticks of the family ixodidae (hard ticks) are vectors and reservoirs of a greater variety of infectious agents than any other ectoparasite. salivary glands of ixodid ticks secrete a large number of pharmacologically active molecules that not only facilitate feeding but also promote establishment of infectious agents. genomic, proteomic and immunologic characterization of bioactive salivary gland molecules are, therefore, important as they offer new insights into ...200717175446
identification of midgut and salivary glands as specific and distinct barriers to efficient tick-borne transmission of anaplasma marginale.understanding the determinants of efficient tick-borne microbial transmission is needed to better predict the emergence of highly transmissible pathogen strains and disease outbreaks. although the basic developmental cycle of anaplasma and ehrlichia spp. within the tick has been delineated, there are marked differences in the ability of specific strains to be efficiently tick transmitted. using the highly transmissible st. maries strain of anaplasma marginale in dermacentor andersoni as a positi ...200717420231
conservation of transmission phenotype of anaplasma marginale (rickettsiales: anaplasmataceae) strains among dermacentor and rhipicephalus ticks (acari: ixodidae).before the eradication of boophilus ticks from the united states, rhipicephalus (boophilus) microplus (canestrini) and rhipicephalus (boophilus) annulatus (say) were important biological vectors of the cattle pathogen anaplasma marginale theiler. in the absence of boophilus ticks, a. marginale continues to be transmitted by dermacentor ticks. however, a few u.s. strains are not transmissible by dermacentor andersoni stiles, dermacentor variabilis (say), or both, raising the question of how these ...200717547235
comparison of the efficiency of biological transmission of anaplasma marginale (rickettsiales: anaplasmataceae) by dermacentor andersoni stiles (acari: ixodidae) with mechanical transmission by the horse fly, tabanus fuscicostatus hine (diptera: muscidae).mechanical transmission ofanaplasma marginale by horse flies (tabanidae) is thought to be epidemiologically significant in some areas of the united states. we compared the relative efficiencies of mechanical transmission of anaplasma marginale by the horse fly, tabanus fuscicostatus hine, during acute infection (approximately 10(7) to approximately 10(9) infected erythrocytes [ie]/ml blood) with biological transmission by dermacentor andersoni stiles in the persistent phase of infection (approxi ...200818283950
tick-borne transmission of two genetically distinct anaplasma marginale strains following superinfection of the mammalian reservoir host.strain superinfection affects the dynamics of epidemiological spread of pathogens through a host population. superinfection has recently been shown to occur for two genetically distinct strains of the tick-borne pathogen anaplasma marginale that encode distinctly different surface protein variants. superinfected animals could serve as a reservoir for onward transmission of both strains if the tick vector is capable of acquiring and transmitting both strains. whether competition among strains dur ...200818573892
independence of anaplasma marginale strains with high and low transmission efficiencies in the tick vector following simultaneous acquisition by feeding on a superinfected mammalian reservoir host.strain superinfection occurs when a second pathogen strain infects a host already carrying a primary strain. anaplasma marginale superinfection occurs when the second strain carries a variant repertoire different from that of the primary strain, and the epidemiologic consequences depend on the relative efficiencies of tick-borne transmission of the two strains. following strain superinfection in the reservoir host, we tested whether the presence of two a. marginale (sensu lato) strains that diff ...200919188360
novel genotypes of anaplasma bovis, "candidatus midichloria" sp. and ignatzschineria sp. in the rocky mountain wood tick, dermacentor andersoni.bovine anaplasmosis, caused by anaplasma marginale, is a vector-borne disease that is enzootic in many parts of the usa. although dermacentor andersoni, a major vector of a. marginale, occurs in canada, the canadian cattle herds are currently considered free of bovine anaplasmosis. there have been two outbreaks of the disease in the province of saskatchewan, but these have been linked to the importation of infected animals. however, the distribution of bovine anaplasmosis may alter with range ex ...201121334146
Displaying items 1 - 61 of 61