TitleAbstractYear(sorted ascending)
factors of variation of amblyomma variegatum infestation on creole cattle in guadeloupe.the level of infestation of "creole" beef cattle of guadeloupe by the tick amblyomma variegatum was recorded during a long-term survey in an experimental farm: 61 steers and 83 cows were distributed in different lots according to sex and management. they grazed continuously either on irrigated digitaria decumbens pastures or on dry native savannahs. tick numbers as well as animal weights were registered monthly. climatic data were also recorded. different acaricide treatments were tested during ...19968784527
development of a computer model of the population dynamics of amblyomma variegatum and simulations of eradication strategies for use in the caribbean.control or eradication efforts should cover wide areas because of long-range migration potential of immature ticks attached to birds, such as cattle egrets. careful follow-up inspections are also imperative. simulation 1 shows how rapidly the population numbers may expand from small numbers, either introduced or missed. simulation 4 indicates extending the treatment cycle beyond the residual effectiveness of the acaricide to save labor or funds would be false economy. the result could be to main ...19968784528
control of amblyomma variegatum and dermatophilosis on local and exotic breeds of cattle in ghana.the occurrence of dermatophilosis on cattle in the tropics is closely associated with infestation by amblyomma variegatum ticks. animals that are more susceptible to the disease also tend to carry higher tick burdens. longitudinal studies carried out on the accra plains suggest that n'dama cattle acquire an enhanced degree of resistance to these ticks following initial exposure. lesions on zebu-type ghana sanga cattle tend to be confined to the predilection feeding sites of adult a. variegatum e ...19968809991
demonstration of vertical transmission of cowdria ruminantium, the causative agent of heartwater, from cows to their of the most important questions about the epidemiology of heartwater in the field is how cowdria ruminatium is transmitted within vertebrate host populations. in this study vertical transmission of c. ruminantium from cows to their calves was demonstrated. twelve mixed-breed calves, born to dams living in a heartwater-endemic area of zimbabwe, were tested post-natally for the presence of c. ruminantium. vertical transmission was demonstrated to occur under natural field conditions using test ...19968750689
the association between amblyomma variegatum and dermatophilosis: epidemiology and immunology.a close association was found between infestation with amblyomma variegatum and the occurrence of dermatophilosis on cattle on the coastal plains of ghana. animals belonging to breeds traditionally regarded as more susceptible to the disease also tended to carry higher tick burdens. the basis of the association between infestation with this tick and the occurrence of dermatophilosis would appear to involve tick-induced immunosuppression.19968809987
ectoparasites (acari, mallophaga, anoplura, diptera) of white-tailed deer, odocoileus virginianus, from southern florida.during a 7-yr period (1984-1990), 300 white-tailed deer, odocoileus virginianus (zimmermann), from 7 localities in collier, dade, and monroe counties in southern florida were examined for ectoparasites. eight species were identified: 4 ticks [ixodes scapularis say, i. affinis neumann, amblyomma maculatum (koch), and dermacentor variabilis (say)], 1 chigger mite [eutrombicula splendens (ewing)], 1 ked (lipoptena mazamae rondani), 1 chewing louse [tricholipeurus lipeuroides (megnin)], and 1 suckin ...19968906911
tropical bont tick eradication campaign in the french antilles. current status.the amblyomma variegatum eradication campaign was officially started in april 1994 in martinique and in guadeloupe, including its dependencies of marie galante, desirade and st martin. a budget of $10.5 and $5.9 million for guadeloupe and martinique, respectively, was initially (1991) calculated and considered necessary to achieve the program. however, eec, the most important donor, estimated that 75% only of this proposal was acceptable, on which it agrees to support a maximum of 50%. the balan ...19968784487
a possible explanation of the apparent breed-related resistance in cattle to bont tick (amblyomma hebraeum) male amblyomma hebraeum tick infestations and the weights of 20 brahman steers and 38 mashona heifers were measured at different periods at the veterinary quarantine area at mbizi, zimbabwe. the experiment for the brahmans lasted 108 weeks and that for the mashona for 113 weeks. the brahman steers weighed a maximum average of 478.4 kg (se 7.9 kg), which was significantly different to the mashona heifers maximum average of 391.4 kg (se 5.6 kg) (p < 0.001). the brahmans had a maximum average ...19969017875
survival of six species of african ticks in relation to saturation deficits.the survival of unfed males and females of six species of african ticks was monitored at five different saturation deficits at constant temperature (25 degrees c). the survivorship curves for each species comprised a pre-mortality period, prior to when ticks started to die and a mortality period corresponding to a rapid increase in the mortality rate. longevity was defined as pre-mortality plus mortality. a negative correlation between the longevity of the ticks and the saturation deficits was f ...19969022266
tick avoidance behaviors associated with a decreased risk of anti-tick salivary gland protein antibody seropositivity in military personnel exposed to amblyomma americanum in arkansas.during april through september 1990, 399 military personnel who originated from either fort chaffee, arkansas (n = 236) or fort wainwright, alaska (n = 163) were studied during maneuvers in tick-infested areas at fort chaffee. study subjects completed a questionnaire and had pre- and post-maneuvers serum specimens analyzed for antibodies to several rickettsial and ehrlichial agents and to amblyomma americanum (lone star tick) salivary gland proteins (anti-tick saliva antibodies [atsa], a biologi ...19968916798
primary isolation of spotted fever group rickettsiae from amblyomma cooperi collected from hydrochaeris hydrochaeris in brazil.this paper reports the first isolation of a spotted fever group rickettsia from an amblyomma cooperi ixodid collected from a capybara (hydrochaeris hydrochaeris) in an endemic area of spotted fever in the county of pedreira, state of são paulo, brazil. isolation was performed in vero cell culture and submitted to immunofluorescence, using antibody from rickettsia rickettsii-positive human serum.19969040845
heartwater in ghana: implications for control of ticks.heartwater, an often fatal rickettsial disease of domestic ruminants transmitted by amblyomma variegatum ticks, ranks with the a. variegatum-associated skin disease dermatophilosis as a major constraint to the upgrading of livestock productivity in ghana. an epidemiological survey, using new diagnostic tests, is being carried out to determine the incidence and distribution of heartwater and other tickborne diseases in ghanaian cattle, sheep and goats. preliminary results from a longitudinal surv ...19968809994
prospects for biological control of livestock ticks, rhipicephalus appendiculatus and amblyomma variegatum, using the entomogenous fungi beauveria bassiana and metarhizium anisopliae.both beauveria bassiana and metarhizium anisopliae induced approximately 30% mortalities in adult rhipicephalus appendiculatus feeding on rabbits while m. anisopliae induced a mortality of 37% in adult amblyomma variegatum. both fungal species induced reductions in engorgement weights, fecundity, and egg hatchability in adult a. variegatum. m. anisopliae reduced fecundity by 94% in a. variegatum. furthermore, b. bassiana reduced egg hatchability to 0%, while 11% of the infected females failed to ...19968812559
a case of tick bite from amblyomma testudinarium on the glans penis.a tick which bit the glans penis of a 40-year-old japanese man was surgically excised together with the skin where the bite occurred. it was identified as amblyomma testudinarium through the taxonomical investigation of its morphological characteristics. to our best knowledge, our patient is the sixth tick bite from this species of tick recorded in the chugoku district of japan.19968839244
effects of pyriproxyfen on engorged females and newly oviposited eggs of the lone star tick (acari:ixodidae).engorged females and 1- to 3-d-old eggs of the lone star tick, amblyomma americanum (l), were exposed to 9 treatments of pyriproxyfen (4, 8, and 16 micrograms/cm2) in glass vials at exposure periods of 7 d, 14 d, and continuous at each dosage level. treatment of newly engorged females did not affect the number of females ovipositing, but the number of eggs oviposited decreased as dosage and exposure time increased. complete inhibition of egg hatch occurred at all treatment levels except that of ...19968840677
the efficacy of amitraz against cattle ticks in tanzania.the efficacy of amitraz on cattle ticks was assessed by susceptibility tests, spraying and dipping trials. tests on the susceptibility of three tick species, rhipicephalus appendiculatus, amblyomma variegatum and boophilus decoloratus to amitraz (technical grade-purity 98.6% w/w) showed all 15 tick strains tested to be highly susceptible, with lc50 ranging between 0.001% and 0.03%, and lc99, between 0.01% and 0.07%. spraying trials were carried out on calves infested with r. appendiculatus, a. v ...19968856759
survival and water-balance characteristics of unfed adult amblyomma cajennense (acari: ixodidae).off-host survival, water balance, and cold tolerance of unfed adult, cayenne ticks, amblyomma cajennense (f.), were examined to evaluate species characteristics important to zoogeography and off-host ecology. survivorship decreased when males and females were subjected to progressively drier constant environmental conditions. average maximum survival was 641.2 and 682.5 d at 85% rh and 23 degrees c (2.98 mm hg) for males and females, respectively. mean survival in both sexes was progressively le ...19968906907
seasonal activity and relative abundance of amblyomma americanum in mississippi.ecological investigations of the lone star tick, amblyomma americanum (l.), were conducted in 3 adjacent 60-m2 plots, located in noxubee national wildlife refuge, noxubee county, mississippi. ticks were collected weekly from july 1992 to july 1993 by flagging randomly selected lanes. during the year, larval ticks were collected first in early july, with peak numbers in september, and they were collected no later than late october. nymphal ticks were collected from mid-march to late october, with ...19968906916
identification of an uncultivable borrelia species in the hard tick amblyomma americanum: possible agent of a lyme disease-like illness.bites from the hard tick amblyomma americanum are associated with a lyme disease-like illness in the southern united states. to identify possible etiologic agents for this disorder, a. americanum ticks were collected in missouri, texas, new jersey, and new york and examined microscopically. uncultivable spirochetes were present in approximately 2% of the ticks. borrelia genus-specific oligonucleotides for the flagellin and 16s rrna genes were used for amplification of dna. products were obtained ...19968568302
amblyomma variegatum (acari: ixodidae): mechanism and control of arbovirus secretion in tick saliva.saliva is considered to be the conduit by which pathogens are transmitted from blood-sucking arthropod vectors to their vertebrate hosts, but supporting evidence for this is fragmentary. to determine if thogoto (tho) virus, a tick-borne member of the influenza virus family, is transmitted via tick saliva, and whether virus replication is a prerequisite for such transmission, two experimental conditions were compared: (1) "biological transmission" and (2) "mechanical transmission." in (1), tho vi ...19968631383
ticks parasitizing humans in georgia and south carolina.from 1990 through 1995, 913 ticks removed from 460 human patients in georgia or south carolina were identified and recorded. the majority of these specimens (758, 83.0%) were lone star ticks, amblyomma americanum. one hundred and four (11.4%) american dog ticks dermacentor variabilis, 36 (3.9%) blacklegged ticks ixodes scapularis, 9 (1.0%) gulf coast ticks amblyomma maculatum, and 6 (0.7%) brown dog ticks rhipicephalus sanguineus were also recovered. all active stages (larvae, nymphs, and adults ...19968636862
dietary modification of host blood lipids affect reproduction in the lone star tick, amblyomma americanum(l.).the feeding and reproductive performance of female lone star ticks (amblyomma americanum (l.)) infesting guinea pigs on diets containing 15% fish oil (fo) or safflower oil (so) were investigated. replete ticks fed on fo-fed guinea pigs weighed approximately 30% less than those on the so-fed guinea pigs. the lower engorged weight resulted in a similar decrease in the mass and number of eggs laid and number of larvae hatching. no effect of host dietary treatment was observed upon the reproductive ...19968604084
ehrlichia-like 16s rdna sequence from wild white-tailed deer (odocoileus virginianus).the reservoir hosts of ehrlichia chaffeensis, etiologic agent of human ehrlichiosis are unknown. initially, white-tailed deer (wtd) were serologically implicated as possible reservoirs of e. chaffeensis. subsequent studies showed that wtd were susceptible to infection with e. chaffeensis and that deer-to-deer transmission by a tick vector, amblyomma americanum, is possible under experimental conditions. to determine if wild wtd were infected with e. chaffeensis, whole blood was collected from 10 ...19968627501
investigation of tick-borne viruses as pathogens of humans in south africa and evidence of dugbe virus infection in a patient with prolonged the course of investigating suspected cases of viral haemorrhagic fever in south africa patients were encountered who had been bitten by ticks, but who lacked evidence of infection with crimean-congo haemorrhagic fever (cchf) virus or non-viral tick-borne agents. cattle sera were tested by enzyme-linked immunoassay to determine whether tick-borne viruses other than cchf occur in the country. the prevalence of antibody in cattle sera was 905/2116 (42.8%) for cchf virus, 70/1358 (5.2%) for dugb ...19968666081
catabolism of dopamine and 5-hydroxytryptamine by monoamine oxidase in the ixodid tick, amblyomma hebraeum.the purpose of this study was to assess biogenic amine catabolism in amblyomma hebraeum koch (an african cattle tick). we assayed haemolymph and saliva for a variety of biogenic amines (usually following injection of substrate into the haemolymph) in partially fed females using hplc coupled to electrochemical detection. dopamine (da) and 5-hydroxytryptamine (5-ht) were rapidly converted to dihydroxyphenylacetic acid (dopac) and 5-hydroxyindoleacetic acid (5-hiaa) respectively, indicating that mo ...19968673075
phylogeny of ticks (ixodida) inferred from nuclear ribosomal dna.phylogenetic relationships of 9 species of ticks were inferred from nucleotide sequences of the d1 domain of large subunit ribosomal dna (rdna), the v4 region of small subunit rdna and sequences immediately adjacent to these regions. six of the 7 subfamilies in the argasidae and ixodidae were represented: ornithodorinae and argasinae from the argasidae (soft ticks); and ixodinae, amblyomminae, haemaphysalinae and rhipicephalinae from the ixodidae (hard ticks). a mite, phytoseiulus persimilis, fr ...19968818731
molecular cloning of delta 9 fatty acid desaturase from the protozoan tetrahymena thermophila and its mrna expression during thermal membrane response to a decrease in its growth temperature, the protozoan tetrahymena is known to increase the level of unsaturated fatty acids in its membrane phospholipids so as to maintain the correct physical state (fluidity) of the membranes. in this organism, synthesis of unsaturated fatty acids is initiated by delta 9 acyl-coa desaturase. our previous studies have shown that, during cold adaptation, the activity of microsomal palmitoyl- and stearoyl-coa desaturase increases, reaching a maximal l ...19968694777
salivary gland changes and host antibody responses associated with feeding of male lone star ticks (acari:ixodidae).the goal of this study was to demonstrate that male lone star ticks, amblyomma americanum (l.), actively feed on rabbits during attachment and that the host is capable of mounting an immune response against male salivary gland proteins. during attachment, it was shown that male ticks salivary glands hypertrophy. an enzyme-linked immunosorbent assay was used to detect rabbit serum proteins in the midgut of previously attached male ticks. sds-polyacrylamide gel electrophoresis showed that the prot ...19968699458
cold-hardiness of a laboratory colony of lone star ticks (acari: ixodidae).the cold-hardiness of a lone star tick, amblyomma americanum (l.), laboratory colony was characterized. fed and unfed larvae, fed and unfed nymphs, and unfed adults did not survive exposure to -17 degrees c for 7 d. after an 8-d exposure to -10 degrees c, adults tolerated cold better than immatures and unfed specimens fared better than fed ticks. exposing unfed 6-wk-old (postmolt) adult males and females to -15 degrees c for increasing intervals up to 2 h suggests that males were more tolerant t ...19968699473
comparison of resistance in three breeds of cattle against african ixodid ticks.tick resistance in three breeds of cattle, two indigenous breeds (arssi and boran) and one boran x friesian cross-bread, were compared following natural tick infestations at abernossa ranch in ethiopia. the local arssi breed was found to have the highest tick resistance, followed by the boran breed, whereas the boran x friesian was the least resistant. over a period of 12 months, from october 1991 to september 1992, a total of 32,897 ticks composed of four genera were collected from the animals. ...19968665816
resistance and cross-resistance in rabbits to adults of three species of african ticks (acari: ixodidae).resistance to rhipicephalus appendiculatus, amblyomma variegatum and amblyomma hebraeum was investigated in the laboratory by infesting rabbits with adults of each of the three species followed by homospecific or heterospecific secondary infestations. significantly lower female engorged weights and egg mass weights were taken as evidence of protective immunity. following a single infestation with adults, rabbits developed homospecific protective immunity (resistance) to only r. appendiculatus an ...19968706589
a self-medicating applicator for control of ticks on deer.a self-medicating applicator for killing ticks on deer and domestic ungulates by passive transfer of acaricides during feeding is described. the applicator consists of a barrel divided into a food bin (above) and a sealed self-contained acaricide reservoir (below) with a vertical, centrally-located ceramic column that extends from the reservoir into the food bin. acaricide is drawn up the column from the sealed reservoir by absorption. animals attracted to the food in the device acquire the acar ...19968744707
efficacy of pheromone-acaricide-impregnated tail-tag decoys for controlling the bont tick, amblyomma hebraeum (acari: ixodidae), on cattle in zimbabwe.a large-scale field test using pheromone-acaricide-impregnated plastic tail-tag decoys demonstrated excellent efficacy of these devices for control of the bont tick, amblyomma hebraeum, on cattle in zimbabwe. the tail tags were impregnated with a mixture containing o-nitrophenol, methyl salicylate, 2,6-dichlorophenol and phenylacetaldehyde and one of three different acaricides (cyfluthrin, flumethrin or alphacypermethrin). o-nitrophenol and methyl salicylate are components of the a. hebraeum att ...19968746132
acquisition of resistance to the tick amblyomma variegatum in boran cattle, bos indicus and the effects of trypanosoma congolense and babesia bigemina on host resistance.resistance was induced in cattle to the tick amblyomma variegatum by five consecutive infestations with nymphs and adults. using the principal component analysis (pca), it was found that percentage of adults engorged, percentage of adults which died, percentage of nymphs which engorged, percentage of nymphs which moulted and percentage of nymphs which died, were the main indicators of resistance against a. variegatum. the percentages of nymphs which engorged or moulted after the third infestatio ...19968686177
systemic treatment of white-tailed deer with ivermectin-medicated bait to control free-living populations of lone star ticks (acari:ixodidae).whole-kernel corn was treated with 10 mg ivermectin per 0.45 kg corn and fed at rate of approximately .45 kg/deer per day to white-tailed deer confined in the treatment pasture, whereas deer in an adjacent control pasture received a similar ration of untreated corn. treatments were dispensed from february through september of 1992 and 1993, and free-living populations of lone star ticks. amblyomma americanum (l.), were monitored in both pastures using dry-ice traps to quantify nymphs and adults ...19968667385
feeding of hard ticks in vitro: new perspectives for rearing and for the identification of systemic acaricides.experiments on in vitro feeding of the hard ticks ixodes ricinus, boophilus microplus, amblyomma variegatum and amblyomma hebraeum are described. an in vitro test for systemic acaricides is presented. work started with a feeding chamber continuously supplied with new blood. it proved too susceptible to fungal contamination and not efficient enough. simple feeding units made of honey jars with an inner glass tube were far more practical. reinforced silicone membrances or baudruche membrances impr ...199611178446
impact on salivary gland degeneration by putative ecdysteroid antagonists and agonists in the ixodid tick amblyomma hebraeumecdysteroids cause salivary gland degeneration in female ixodid ticks. we tested the effects of the following compounds on salivary gland degeneration in the ixodid tick amblyomma hebraeum koch: hhcs (22s,23s-homocastasterone), ssbr (22s,23s-homobrassinolide), stgm (2alpha,3alpha(oh)2-delta22-stigmasten-6-one), rh 5849, and rh 5992. the first three are brassinosteroids (putative ecdysone antagonists) and the last two are nonsteroidal mimics of ecdysone in a variety of insects. in vitro, hhcs (up ...19968980038
[insects know no border.].one of the major consequences of the joined action of demographic pressure and evolution of human activities lies in enormous increase of transportation, both in frequence and speed; taking advantage of these facilities, some arthropods could increase their geographical distribution and create new health threats. several demonstrative examples are exposed in order to illustrate this anthropic dissemination of the vectors : the introduction of anopheles gambiae s.l. in mauritius island between 18 ...199617292311
artificial feeding of amblyomma cajennense (fabricius, 1787) (acari:ixodidae) through silicone artificial feeding system was used where citrated bovine blood was offered to male and female amblyomma cajennense. vestiges of blood, sweat, hair and exfoliated skin were used as phago-stimulants placed on the surface of the silicone membrane. the ticks were collected, as engorged nymphs, from naturally infested equines, with the ecdysis occurring in the laboratory. four hundred ticks were used, 50% being female, at three to four weeks post-ecdysis. vestiges of blood on the silicone membrane ...19979361751
impact of feeding, molting and relative humidity on cuticular wax deposition and water loss in the lone star tick, amblyomma determine whether there is a correlation between the amount of lipids on the surface of ticks and their permeability to water, we quantified cuticular surface wax and measured water-loss rates in the ixodid tick amblyomma americanum from nonfed nymph to egg-laying female. ticks deposited no extra cuticular lipids during feeding, permitting maximum transpiratory water loss that presumably helps to concentrate the bloodmeal; and ticks deposited additional cuticular wax after apolysis that reduc ...199712770417
serological survey of heartwater relative to the distribution of the vector amblyomma variegatum and other tick species in north cameroon.a study was carried out on the spatial and temporal distribution of amblyomma variegatum and other ticks infesting sheep and goats in northern cameroon. a serological survey of heartwater (cowdriosis) using a competitive elisa was concurrently carried out in the same flocks. a. variegatum was found to be the most predominant species accounting for 48.3% of all the ticks collected. other species identified included rhipicephalus sulcatus, r. lunulatus, r. turanicus, boophilus decoloratus, b. annu ...19979066062
field sampling of the tick amblyomma variegatum (acari: ixodidae) on pastures in guadeloupe; attraction of co2 and/or tick pheromones and conditions of use.field experiments were conducted in guadeloupe to evaluate the attraction of different chemicals on a guadeloupean strain of amblyomma variegatum. such tick sampling techniques may help to assess the size of the tick population on pastures before, during and after an attempted tick eradication campaign. co2 was absolutely necessary to activate ticks, including the larvae. in addition to activation, our data suggested that co2 itself is attractive for ticks. the reactivity of the ticks varied gre ...19979080680
new distribution records of amblyomma americanum (l.) (acari: ixodidae) in new york state.amblyomma americanum, commonly called the lone star tick, has been widely-distributed in the southeastern united states for many years. distribution of this species apparently did not extend to new york state until the 1970s, after which the northern distribution in new york was limited to long island (suffolk and nassau counties), where it has become locally abundant. since then, there has been just one published record from new york state, in westchester county, just north of new york city. fr ...19979491364
evidence for attachment pheromones in the cayenne tick (acari:ixodidae).evidence is presented for the existence of male-produced attachment pheromones in the tick amblyomma cajennense (f). unfed males and females attached significantly faster to shaved sides on bovine hosts where preattached males were present than did adult ticks released in control areas. attached ticks did not form clusters around the preattached males as described for other species of amblyomma. they attached in areas under bags where they had been released, but were not necessarily close to the ...19979103768
the impact of ixodiphagus hookeri, a tick parasitoid, on amblyomma variegatum (acari: ixodidae) in a field trial in an experiment to investigate the effect of the tick parasitoid, ixodiphagus hookeri, on tick numbers on cattle, 150000 parasitoids were released over a period of 1 year in a field where ten cattle infested with multiple tick species were kept. amblyomma variegatum was reduced from 44 to two ticks per animal while rhipicephalus appendiculatus increased over the time of parasitoid release. during the time of release 51% of the nymphs of a. variegatum collected from the animals were parasitized. ...19979080682
some factors affecting infestation of white-tailed deer by blacklegged ticks and winter ticks (acari:ixodidae) in southeastern missouri.a total of 5,669 ticks of 4 species was collected from 515 hunter killed, white-tailed deer. odocoileus virginianus (zimmerman), in southeastern missouri from 1993 through 1995. the american dog tick, dermacentor variabilis (say) (4 adults), the lone star tick, amblyomma americanum (l.) (57 adults, 2 nymphs), the blacklegged tick, ixodes scapularis (say) (3,120 adults), and the winter tick, dermacentor albipictus (packard) (2.059 adults, 436 nymphs, 1 larva) were collected. patterns of adult d. ...19979151505
prostaglandin biosynthesis by salivary glands isolated from the lone star tick, amblyomma americanum.salivary glands separated from internal tissues of the lone star tick, amblyomma americanum, are competent to synthesize prostaglandins (pgs). using an in vitro pg biosynthesis assay four major pgs, namely, pga2/pgb2, pgd2, pge2, and pgf2 alpha were synthesized. under standard assay conditions pga2/pgb2 was the predominant product. salivary tissues as well as non-salivary internal tissues were capable of pg biosynthesis. we observed that storing ticks at -80 degrees c for 3 months resulted in re ...19979090120
identification of hemolytic activity in saliva of the lone star tick (acari:ixodidae).hemolytic activity was identified in the saliva of amblyomma americanum (l.) when red blood cells from sheep were incubated with tick saliva in the presence of phosphatidylcholine and sodium deoxycholate. the hemolytic activity was destroyed by boiling or treating with trypsin. the hemolytic activity in tick saliva was calcium-dependent, and inhibited by a phospholipase a2 inhibitor oleyloxyethyl phosphorylcholine. phosphatidylserine could replace phosphatidylcholine in the hemolytic assays but ...19979103758
tick-raccoon associations and the potential for lyme disease spirochete transmission in the coastal plain of north carolina.raccoons (procyon lotor) were live-trapped and examined for ticks from july 1990 to july 1993 in the coastal plain of north carolina on marine corps base, camp lejeune, north carolina (usa). five species of ixodid ticks were found on 351 (78%) of 449 raccoons. amblyomma americanum was the most abundant tick found on raccoons. dermacentor variabilis, ixodes texanus, and ixodes scapularis were frequently collected, while ixodes cookei were rarely collected from raccoons. tick burdens were not affe ...19979027688
isolation of the causative agent of heartwater (cowdria ruminantium) from three amblyomma species in eight districts of kenya.thirteen isolates of cowdria ruminantium were made from eight different districts of kenya by four different isolation methods. feeding adult amblyomma species ticks derived from nymphs collected in the field and the inoculation of homogenates prepared from adult field ticks had the highest success rate. the reattachment of adult ticks collected in the field was successful on only one of five attempts, and the subinoculation of blood from suspected heartwater carriers was unsuccessful. seven of ...19979004475
cloning and sequence of a gene for a homologue of the c subunit of the v-atpase from the salivary gland of the tick amblyomma americanum (l).a 1084 base pair partial cdna showing similarity to the c subunit of the vacuolar atpase (v-atpase) was isolated on a clone from a cdna library made from salivary glands from 3-day-old feeding adult amblyomma americanum (l.) female ticks. the 5' end was completed using primer extension and the two pieces joined to form a complete cdna of 1373 bp. this mrna is expressed in embryos and the salivary glands of unfed adults and adult females at all stages of feeding. specific inhibitors of the v-atpa ...19979013257
identification and characterization of anticoagulant activities in the saliva of the lone star tick, amblyomma americanum (l.).anticoagulant activities against both the extrinsic and intrinsic coagulation pathways were identified in the saliva of partially fed female lone star ticks, amblyomma americanum (l.). the activities of factor xa and thrombin in the common pathway of the coagulation cascade were inhibited by tick saliva. the greatest anticoagulant activities were found in the saliva of ticks weighing more than 200 mg. the anticoagulant activities in tick saliva could be detected without preincubation of tick sal ...19979057694
natural history of ehrlichia chaffeensis (rickettsiales: ehrlichieae) in the piedmont physiographic province of georgia.the roles of wild mammals and ticks in the epidemiology of ehrlichia chaffeensis at a suspected endemic site were investigated using serologic testing, culture, and polymerase chain reaction (pcr) supported by restriction endonuclease analysis and dna sequencing. antibodies reactive to e. chaffeensis (> or = 1:64) were detected in 92% of white-tailed deer (odocoileus virginianus), 21% of raccoons (procyon lotor), and 8% of opossums (didelphis virginianus), but not in 8 other species of mammals. ...19979379294
helminths and arthropods of black and white rhinoceroses in southern africa.helminths and arthropods were collected and quantified from two black rhinoceroses (diceros bicornis bicornis) and one white rhinoceros (ceratotherium simum), and ticks from an additional four black and two white rhinoceroses in southern africa. the helminths of a black rhinoceros from the republic of south africa and one from namibia were quantitatively measured and recorded for each compartment of the alimentary tract. probstmayria vivipara was the most abundant parasite in each animal. a rece ...19979249695
enema infusion technique inappropriate for evaluating viral competence of determine whether anal infusion of virus simulates the natural route of infection rather than intracoelomic injection, we compared the course of venezuelan equine encephalitis (vee) virus infection in amblyomma cajennense (f.) ticks that had been exposed to virus by enema infusion with that in ticks fed on a viremic host or exposed by intracoelomic inoculation. although virus was detected in virtually all ticks 14 d after exposure, orally exposed ticks contained significantly less virus (10(1 ...19979151493
rickettsiae-infected ticks in an endemic area of spotted fever in the state of minas gerais, brazil.a study on tick-borne rickettsiosis was developed in the county of santa cruz do escalvado, state of minas gerais, brazil, where a clinical case of the disease, confirmed by necropsy, had been reported. of the 1,254 ticks collected, 1,061 belonged to the amblyomma genus, 57 to the rhipicephalus sanguineus species, 81 to boophilus microplus, and 46 to anocentor nitens. the hemolymph test associated with giménez staining showed that 18 of the 221 a. cajennense specimens, 1 of the 16 r. sanguineus, ...19979361740
a novel neuropeptide-endocrine interaction controlling ecdysteroid production in ixodid ticks.ixodid (hard) ticks are blood-feeding arthropods that require a blood meal to complete each stage of development. however, the hormonal events coordinating aspects of feeding and development are only poorly understood. we have delineated a new neuropeptide-endocrine interaction in the adult tick, amblyomma hebraeum, that stimulates the synthesis of the moulting hormones, the ecdysteroids. in adult female ticks, ecdysteroid synthesis could be demonstrated in integumental tissue incubated in vitro ...19979149427
ticks infesting sheep and goats in the sudan.very little work has been carried out on ticks infesting small ruminants in the sudan. of some 70 tick species recorded in the sudan, 34 species of different genera were collected from sheep and goats, two belonging to the genus amblyomma, seven to the genus hyalomma, 22 to the genus rhipicephalus and three to the genus boophilus. nevertheless, their distribution, the seasonal abundance and population dynamics are poorly studied. particularly, the peculiar distribution of a. lepidum and a. varie ...19979530698
erythema migrans-like rash illness at a camp in north carolina: a new tick-borne disease?borrelia burgdorferi, the causative agent of lyme disease, has never been isolated from a patient thought to have acquired lyme disease in any southeastern state.19979531233
genetic markers for the identification of two tick species, amblyomma dissimile and amblyomma rotundatum.genetic markers are described for 2 species of reptile and amphibian ticks, amblyomma dissimile and amblyomma rotundatum, by allozyme electrophoresis. fixed allelic differences in 4 out of the 8 examined loci allowed the unequivocal separation of both of these species. a strong correlation was found between these genetic markers and the relative size of the spurs in coxae iv but not with the punctuation pattern of the scutum. moreover, no overlap was found in the distribution of relative spur si ...19979194816
assay for phenoloxidase activity in amblyomma americanum, dermacentor variabilis, and ixodes scapularis.phenoloxidase activity in amblyomma americanum, dermacentor variabilis, and ixodes scapularis was assayed. no phenoloxidase activity was detected compared to high activity through time in larvae of the greater wax moth (galleria mellonella). we conclude that activated prophenoloxidase does not act as an opsonin in ixodid ticks tested to date.19979194851
attempted transmission of human granulocytotropic ehrlichia (hge) by amblyomma americanum and amblyomma maculatum.transstadial transmission of human granulocytotrophic ehrlichia (hge) was attempted in dogs using amblyomma americanum (l.) and a. maculatum koch, two species that, as adults, feed readily on human beings. larvae and nymphs were acquisition-fed on a dog that was parasitemic with hge. two months later, following digestion of the blood meal and subsequent molting to nymphal or adult stage, these ticks were fed to repletion on hge-naive dogs. none of the dogs developed clinical evidence of ehrlichi ...19979195722
isolation of ehrlichia chaffeensis from wild white-tailed deer (odocoileus virginianus) confirms their role as natural reservoir hosts.field and experimental studies have implicated white-tailed deer (odocoileus virginianus) as probable reservoir hosts for ehrlichia chaffeensis, the causative agent of human monocytic ehrlichiosis, but natural infection in deer has not been confirmed through isolation of e. chaffeensis. thirty-five white-tailed deer collected from three amblyomma americanum-infested populations in georgia were examined for evidence of e. chaffeensis infection by serologic, molecular, cell culture, and xenodiagno ...19979196173
epidemiological aspects of the brazilian spotted fever: seasonal activity of ticks collected in an endemic area in são paulo, brazil.ticks were collected from vegetation and animals at monthly intervals during one year (1993-1994) in an endemic area of brazilian spotted fever in the country of pedreira, state of são paulo. six species of ticks were identified amblyomma cajennense, amblyomma cooperi, amblyomma triste, anocentor nitens, rhipicephalus sanguineus and boophilus microplus. only the first species was sufficiently numerous to permit a quantitative study with seasonal activity, although the distribution and source of ...19979197151
acquisition of protective immunity in geochelone pardalis against amblyomma marmoreum (acari:ixodidae) nymphal ticks.significant increases in serum globulins (alpha 1, alpha 2, beta and gamma) were observed in mountain leopard tortoises (geochelone pardalis) after they had been immunized with nymphal homogenates of amblyomma marmoreum. there was a concomitant significant increase in the numbers of leukocytes (lymphocytes, basophils, monocytes and eosinophils). resistance to nymphal-challenge infestations was manifested by reduced feeding time, lower engorgement masses, and significantly fewer (p < 0.0001) numb ...19979204497
development and evaluation of a recombinant antigen, monoclonal antibody-based competitive elisa for heartwater serodiagnosis.cowdria ruminantium is the etiologic agent of heartwater, a tick-transmitted foreign animal disease with considerable potential for entrance into the usa. a competitive enzyme-linked immunosorbent assay (celisa) was developed to detect serologic responses to c. ruminantium infection. the celisa utilized a recombinant form of the c. ruminantium major antigenic protein (map-1) as the antigen and an anti-map-1 monoclonal antibody as the competing indicator reagent. experimental antisera to c. rumin ...19979211230
pyriproxyfen effects on newly engorged larvae and nymphs of the lone star tick (acari:ixodidae).newly engorged larvae and nymphs of the lone star tick, amblyomma americanum (l.), were exposed to 9 treatments of pyriproxyfen in glass vials consisting of dosages of 4, 8, and 16 micrograms/cm2 for 7 d, 14 d, and continuous exposure periods at each concentration. treatment of newly engorged larvae resulted in decreased molting, altered postmolt defecation, and nymphal survival with results being dose and exposure dependent. molting inhibition ranged from 35.9 to 68.4%. successfully molted nymp ...19979103764
ability of the lyme disease spirochete borrelia burgdorferi to infect rodents and three species of human-biting ticks (blacklegged tick, american dog tick, lone star tick) (acari:ixodidae).the infectivity of a diverse collection of borrelia burgdorferi strains from north america for mice was determined as a prelude to vector competence experiments with the 3 primary human-biting tick species in the eastern united states (ixodes scapularis say, dermacentor variabilis (say), amblyomma americanum (l.)]. of the 34 b. burgdorferi strains inoculated into mice, 29 were infectious; the exceptions were 5 isolates from texas. vector competence experiments were conducted with 2 strains from ...19979220680
ticks (acari: ixodida) uncommonly found biting humans in north carolina.collection records are presented that document human-biting by otobius megnini, amblyomma maculatum, haemaphysalis leporispalustris, ixodes cookei, ixodes dentatus, and rhipicephalus sanguineus in north carolina. these species are either extremely rare in north carolina or they are normally considered non-human feeders. the record of otobius megnini represents the first collection of this species in north carolina in over 50 years. it is proposed that immature rhipicephalus sanguineus feed on hu ...19979221733
african tick-bite fever. an imported spotless characterize the clinical presentation and course of african tick-bite fever, a recently rediscovered rickettsiosis caused by rickettsia africae (a new species within the spotted fever group of rickettsiae), to establish its relationship with amblyomma tick species, and to discuss its role in the etiology of fever in patients who are returning from the tropics.19978996049
identification of an ixodes ricinus salivary gland fraction through its ability to stimulate cd4 t cells present in balb/c mice lymph nodes draining the tick fixation site.balb/c mice infested with larvae or nymphs of ixodes ricinus develop in their lymph nodes a t cell-specific immune response triggered by salivary gland soluble antigens (sga). sga are apparently conserved in the 3 biological stages of i. ricinus ticks and are species specific. sga derived from partially fed females i. ricinus stimulate lymph node t cells from mice infested with i. ricinus larvae or nymphs. in contrast, lymph node cells from mice infested with amblyomma hebraeum nymphs do not res ...19979226956
cloning and sequence of a gene for the homologue of the stearoyl coa desaturase from salivary glands of the tick amblyomma americanum.a 1488 base pair cdna clone has been isolated from a cdna library made from salivary glands from 3-day feeding adult female ticks. the sequence of this cdna suggests it is the gene for the tick homologue of the stearoyl coa desaturase. this gene is expressed in eggs and all feeding stages of the adult examined, but appears to be transcribed to an 8 kb mrna as well as a 1.5 kb mrna. because ticks have the ability to synthesize monounsaturated fatty acids and demonstrate a large increase in saliva ...19979272444
isolation and characterization of americanin, a specific inhibitor of thrombin, from the salivary glands of the lone star tick amblyomma americanum (l.).a thrombin (ec inhibitor (americanin) was isolated from the salivary glands of the lone star tick amblyomma americanum (l.) using reversed-phase chromatography and anion-exchange chromatography. americanin did not inhibit any other protease tested, including factor xa, plasmin, trypsin, chymotrypsin, elastase, papain, pepsin, and carboxypeptidase. the inhibition of thrombin by americanin decreased dramatically with dilution of the reaction mixture including thrombin, its substrate, and ...19979287955
seroepidemiology of rickettsia typhi, spotted fever group rickettsiae, and coxiella burnetti infection in pregnant women from urban tanzania.immunofluorescent antibody (ifa) testing was performed on sera drawn from 150 pregnant women in the port city of dar es salaam, tanzania. prevalence of antibodies to rickettsia typhi was 28%, higher than in any of the 12 other african countries in which serosurveys using ifa testing have been performed. seroprevalence of antibodies to spotted fever group rickettsiae antigens was 25.3%, comparable with that found in other sub-saharan countries endemic for amblyomma ticks. only 4.7% of women were ...19979288814
different organisms associated with heartwater as shown by analysis of 16s ribosomal rna gene sequences.cowdria ruminantium is a rickettsial parasite which causes heartwater, a economically important disease of domestic and wild ruminants in tropical and subtropical africa and parts of the caribbean. because existing diagnostic methods are unreliable, we investigated the small-subunit ribosomal rna (srrna) gene from heartwater-infected material to characterise the organisms present and to develop specific oligonucleotide probes for polymerase chain reaction (pcr) based diagnosis. dna was obtained ...19979299697
development and use of specific polymerase reaction for the detection of an organism resembling ehrlichia sp. in white-tailed deer.the role of white-tailed deer (odocoileus virginianus) in the epidemiology of ehrlichia chaffeensis and the agent of human granulocytic ehrlichiosis (hge) is not fully understood, and diagnostic procedures may be complicated by the recent detection of 16s rdna sequence from an ehrlichia sp.-like organism in wild deer. a specific forward primer (dga) and an ehrlichia spp. reverse primer (ga1ur) were constructed to amplify this new, distinct ehrlichia sp.-like 16s rdna. the dga primer, a forward p ...19979131554
a specific prostaglandin e2 receptor and its role in modulating salivary secretion in the female tick, amblyomma americanum (l.).prostaglandins of the 2-series (e.g. pge2) are typically synthesized from arachidonic acid (aa) after aa is released from cellular phospholipids after activation of an intracellular phospholipase a2 (pla2). treatment of isolated salivary glands with pla2 inhibitor oleyloxyethyl phosphorylcholine (opc) or prostaglandin synthetase inhibitors reduced dopamine-induced fluid secretion and cyclic amp (camp) levels in isolated salivary glands. pge2 and its analog, 17-phenyl trinor pge2, partly reversed ...19979219365
the effects of the bont tick, amblyomma hebraeum, on milk production of sanga and sanga x brahman cattle.the effects of adults on the bont tick, amblyomma hebraeum on the milk production of sanga and sanga x zebu (brahman) cattle were measured over a period of 11 weeks in the low veld of zimbabwe in the summer of 1986. four groups of lactating cows, consisting of two breeds, each divided into a high and low tick treatment, were exposed to very low or high challenges of ticks and their milk production measured by weighing their calves before and after suckling. the liveweight gains (lwg) of the calv ...19979226643
short report: geographic distribution of different genetic types of ehrlichia chaffeensis.the 120-kd protein gene of ehrlichia chaffeensis was used to characterize ehrlichial dna from seven pools of adult amblyomma americanum ticks. ticks from missouri, kentucky, and north carolina contained e. chaffeensis dna of the arkansas strain genotype. ticks from north carolina also contained ehrlichiae of the sapulpa strain genotype, originally identified in oklahoma.19979230803
crimean-congo haemorrhagic fever virus infection in the western province of saudi 1990, an outbreak of suspected viral haemorrhagic fever involving 7 individuals occurred in mecca in the western province of saudi arabia. congo-crimean haemorrhagic fever (cchf), not previously known to be present in saudi arabia, was incriminated. a study of the epidemiology of this virus was therefore carried out in mecca, and in nearby jeddah and taif in 1991-1993; 13 species of ixodid ticks (5 hyalomma spp., 5 rhipicephalus spp., 2 amblyomma spp., 1 boophilus sp.) were collected from liv ...19979231193
on the mechanism of water vapour sorption from unsaturated atmospheres by ticksthe nascent salivary secretion of 41 partly dehydrated and unfed adult female amblyomma variegatum, 5&shy;8 months post-ecdysis, during water vapour uptake at 93.5 % relative humidity and 20 &deg;c, had an osmolality of between 298.6 and 769.7 mosmol kg-1 (mean &plusmn; s.d. 470.3&plusmn;85.8 mosmol kg-1). this range would allow water vapour uptake at relative humidities of approximately 98&shy;99 %, but it would not suffice for lower relative humidities down to 80&shy;85 %, the critical equilib ...19979319391
a novel phospholipase a2 activity in saliva of the lone star tick, amblyomma americanum (l.).saliva from female lone star ticks, amblyomma americanum, contained a novel phospholipase a2 (pla2) activity that hydrolyzed 14c-arachidonate from 14c-arachidonyl phosphatidylcholine. the tick saliva pla2 (ts-pla2) was active over a broad ph range (4.5-11.5) with two distinct ph optima of ph 5.5 and 9.5. though extracellular pla2s are reported to be activated by millimolar ca2+, ts-pla2 was sensitive to submicromolar ca2+ and was half-maximally activated by 3.5 microm ca2+. tick saliva contains ...19979326887
crimean-congo hemorrhagic fever in ticks (acari: ixodidae) and ruminants: field observations of an epizootic in bandia, senegal (1989-1992).from 1989 to 1992, a longitudinal study of the relationships between different tick species and domestic ungulates in the transmission and amplification of crimean-congo hemorrhagic fever (cchf) virus was undertaken in the bandia area in senegal where the presence of the virus had been reported previously. an epizootic occurred in 1991-1992 and 22 strains of cchf virus were isolated from hyalomma marginatum rufipes koch, amblyomma variegatum (f.), rhipicephalus guilhoni morel & vassiliades, and ...19979379454
seasonal prevalence of ticks and tick-transmitted haemoparasites in traditionally managed n'dama cattle with reference to strategic tick control in the gambia.a survey of tick spatial and seasonal distribution in traditional managed n'dama cattle over 1 year old was carried out in the gambia over 16 months. presence of anaplasma marginale and babesia spp. in the blood smears and their antibodies in the serum of same animals were also examined. tick species, in decreasing order of abundance, were: boophilus geigy, rhipicephalus senegalensis, b.decoloratus, hyalaomma truncatum, h.marginatum rufipes and amblyomma variegatum. all tick species peaked durin ...19979430113
biases associated with several sampling methods used to estimate abundance of ixodes scapularis and amblyomma americanum (acari: ixodidae).several tick sampling methods were evaluated for ixodes scapularis say and amblyomma americanum (i.) in oak-dominated mixed hard-wood, pitch pine-dominated, and mixed hardwood and pine forests in coastal new jersey. walking surveys were more efficient for collecting i. scapularis adults than dragging by a factor of > 2:1. in contrast, drag sampling yielded nearly twice as many a. americanum adults compared with walking surveys. i. scapularis subadults were rarely collected during walking surveys ...19979439115
isolation of a functional ecdysteroid receptor homologue from the ixodid tick amblyomma americanum (l.).ecdysteroids are assumed to be the major steroid hormones in arthropods. however, with the exception of insects and crustaceans, very little is known about ecdysteroid action in other arthropods. to determine if ecdysteriods play a functional role in the ixodid tick, amblyomma americanum (l.), we isolated cdnas encoding three presumed ecdysteroid receptor isoforms (aamecra1, aamecra2, and aamecra3) that have common dna and ligand binding domains linked to distinct amino termini. the dna and liga ...19979501418
human ehrlichioses: newly recognized infections transmitted by ticks.human ehrlichioses are tick-borne infections caused by bacteria in the genus ehrlichia. human monocytic ehrlichiosis is caused by ehrlichia chaffeensis and human granulocytic ehrlichiosis is caused by an agent similar to ehrlichia equi. e. chaffeensis infects mononuclear phagocytes and is transmitted by lone star ticks (amblyomma americanum) found in the south central and eastern united states. the agent of human granulocytic ehrlichiosis infects mostly neutrophils, it transmitted by ixodes spec ...19989509259
host specificity of amblyomma cajennense (fabricius, 1787) (acari: ixodidae) with comments on the drop-off rhythm.the parasitic specificity of larval, nymph and adult amblyomma cajennense on six different host species: oryctolagus cuniculus, rattus norvegicus, gallus gallus domesticus, anas platyrhynchus, coturnix coturnix and streptopelia decorata is described. in terms of the numbers of larvae and nymphs recovered, o. cuniculus was the best host species. the modal day for drop-off of larvae and nymphs was day three for the mammal hosts, but variable in the birds. we conclude that adult a. cajennense have ...19989698869
effect of controlling natural field-tick infestation on the growth of n'dama and gobra zebu cattle in the gambia.the effect of tick infestations on liveweight gain (lwg) was assessed by comparison of weight changes in flumethrin-treated n'dama and gobra zebu cattle (16-20 months old) with respective control groups submitted to natural tick challenge over 1 year. flumethrin was applied monthly, fortnightly or weekly. preventive treatments against anaplasmosis, babesiosis and trypanosomosis were given. mortality rate was recorded and post-mortem examinations carried out. in both treated and control animals, ...19989604263
efficacy of tags impregnated with pheromone and acaricide for control of amblyomma variegatum.the efficacy of tags impregnated with pheromone and acaricide for control of amblyomma variegatum on cattle in guadeloupe was determined for a 13-week trial. comparisons were made between untreated cattle and cattle with tags containing either pheromones alone (o-nitrophenol, methyl salicylate, 2,6-dichlorophenol and phenylacetaldehyde), pheromones plus acaricide (cyfluthrin or deltamethrin), or acaricide alone. tags were fastened to cattle both on collars on the neck and with adhesive to tail h ...19989622367
illustrated key to nymphs of the tick genus amblyomma (acari: ixodidae) found in the united states.a dichotomous identification key, with important characters illustrated by scanning electron micrographs, is provided for nymphs of the 9 species of the genus amblyomma occurring in the united states. species included are a. americanum (l.), a. cajennense (f.), a. dissimile koch, a. imitator kohls, a. inornatum (banks), a. longirostre (koch), a maculatum koch, a. rotundatum koch, and a. tuberculatum marx. notes on the geographical distributions, medical and veterinary importance, and nymphal sta ...19989701933
phospholipase a2 activity in salivary glands and saliva of the lone star tick (acari: ixodidae) during tick feeding.phospholipase a2 (pla2) activity levels in tick [amblyomma americanum (l.)] salivary glands and saliva were examined during tick feeding by using 14c-phosphatidylcholine as the substrate. saliva produced by stimulating female ticks to salivate with dopamine contains pla2 (ts-pla2) activity. the ts-pla2 activity level in saliva did not change significantly during tick feeding except for a decrease in the last rapid feeding phase (> 200 mg) and in replete ticks. phospholipase a2 activity was highe ...19989701935
interaction of entomopathogenic nematodes (steinernematidae) with selected species of ixodid ticks (acari: ixodidae).entomopathogenic nematodes, currently used for biological control of various insect pests, were tested for their ability to penetrate and kill replete females of several species of ticks including dermacentor variabilis (say), rhipicephalus sanguineus (latreille), amblyomma maculatum koch, and a. cajennense (f.). these species were found to be susceptible to the entomopathogenic nematodes, steinernema feltiae (filipjev) or s. riobravus (cabanillas & poinar), shown in previous studies in our labo ...19989701938
ecdysteroid regulation of salivary gland degeneration in the ixodid tick, amblyomma hebraeum: a reconciliation of in vivo and in vitro observations.salivary gland degeneration in the female tick amblyomma hebraeum koch is triggered by an ecdysteroid (es) hormone. under both in vivo and in vitro conditions, degeneration requires 4 days for completion. in partially fed females that have fed beyond a "critical weight," the commitment period for salivary gland degeneration occurs between 24 and 48 h after removal from the host. although tissue degeneration begins within 24 h postengorgement, es titer as measured by radioimmunoassay (ria) does n ...19989473365
distribution, abundance, and seasonal activities of ticks collected from rodents and vegetation in south carolina.ixodid ticks were collected from live-trapped rodents and by flagging vegetation at sites in the piedmont, sandhills, coastal plain, and coastal zone of south carolina from may 1994 through december 1995. a total of 1,514 ticks was recovered from 237 live-trapped rodents. host-attached species included ixodes minor neumann (n = 818), dermacentor variabilis (say) (n = 346), amblyomma maculatum koch (n = 209), ixodes affinis neumann (n = 89), and ixodes scapularis say (n = 52). species of questing ...19989673934
isolation of two functional retinoid x receptor subtypes from the ixodid tick, amblyomma americanum (l.).retinoid x receptors (rxr) play a central role in a variety of nuclear signaling pathways in both vertebrates and invertebrates. vertebrate rxrs are encoded by a multigene family whereas the insect rxr homologue, ultraspiracle (usp), is encoded by a single gene. to determine if acarines possess an rxr homologue similar to insect usps, we isolated cdnas encoding two distinct rxr genes, aamrxr1 and aamrxr2, from the ixodid tick, amblyomma americanum (l.). the dna binding domains share 95 and 87% i ...19989705073
dynamics of free-living ixodid ticks on a game ranch in the central province, ixodid ticks were collected at monthly intervals from january to december 1996 by dragsampling the vegetation of mtendere game ranch in the chisamba district of the central province, zambia. ticks belonging to 11 species were recovered. rhipicephalus appendiculatus was most abundant, comprising 90% of the total number collected. all life stages of this tick showed a definite seasonal pattern of activity. the adults were present mainly during the rainy season (february and march), the ...19989629590
delivery of ivermectin by injectable microspheres.a bioabsorbable, injectable microsphere formulation containing ivermectin in poly-(lactide-co-glycolide) copolymer (pla/pga) was developed to provide long-lasting delivery of the drug for control of livestock pests. a solvent-evaporation technique was used to produce the spherical beads containing approximately 30% ivermectin and ranging in size from 25-250 microns. the pattern of delivery of the drug into the blood stream of spanish goats was characterized for a 50:50 pla/pga, a 90:10 pla/pga c ...19989650514
antibody to a cdna-derived calreticulin protein from amblyomma americanum as a biomarker of tick exposure in humans.the antibody responses of human and animal hosts were studied to determine the utility of antibody against recombinant tick calreticulin (rtc), a cdna-derived protein isolated from salivary glands of amblyomma americanum l., as a biologic marker of tick exposure. rabbits fed upon by either a. americanum or dermacentor variabilis say developed significant anti-rtc antibody responses, as measured by both elisa and immunoblot assay. in contrast, gerbils exposed to aedes aegypti did not develop anti ...19989715947
physician-diagnosed erythema migrans and erythema migrans-like rashes following lone star tick differentiate cases of physician-diagnosed erythema migrans and erythema migrans-like rashes associated with lone star tick (amblyomma americanum) bites.19989722725
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