observations on cattle ticks in huila province (angola).in huila province of angola, 3864 ticks were collected during a parasitological survey carried out in the rainy season from october 1990 to april 1991. the samples were collected from cattle gathered for the annual vaccination campaign against contagious bovine pleuropneumonia, anthrax and blackleg in 18 veterinary stations of six municipalities. after tick classification, the following proportions of ticks were obtained: rhipicephalus evertsi mimeticus (27.1%), amblyomma pomposum (26.4%), booph ...19948171837
prevalence of borrelia (spirochaetaceae) spirochetes in texas ticks.between 1990 and 1992, ticks from eight texas parks were collected and analyzed to determine the prevalence of spirochete-infected ticks. borrelia spirochetes were detected in 1.03% of 5,141 amblyomma americanum (l.) adults examined, a species texas residents often encounter. no spirochetes were observed in the other tick species tested.19948189421
[epidemiology of cowdria infection in senegal. i. study of the transmission and infection level in amblyomma variegatum (fabricius, 1794) in the niayes region].the authors report the results of research on infection rates of amblyomma variegatum nympha and imago populations by cowdria ruminantium in the niayes region as well as on the transmission rates of a. variegatum by the various stases. the experiments were carried out on sheep from the sahelian zone where the vector tick is not endemic. the infection rate, estimated by inoculating sheep with ground ticks, gave the following prevalences: t = 13.3% for nymphae and t = 1.2% for adults. the transmis ...19938190980
[epidemiology of cowdria infection in senegal. ii. results of sero-epidemiological follow-up studies].the authors report the results of sero-epidemiological monitoring of zebu, diakoré and ndama cattle in the sahel, niayes and north guinea zones, respectively. calves aged 0-3 or 3-6 months were subjected to blood sampling every three months for a period of 20 months. in the niayes and north guinea zones, the immunofluorescence test showed that about 70% of 0-1 month old calves reacted positively to the cowdria ruminantium antigen, whereas the prevalence was 92% between 3 and 6 months. after the ...19938190981
in vitro feeding of instars of the ixodid tick amblyomma variegatum on skin membranes and its application to the transmission of theileria mutans and cowdria in vitro feeding method using rabbit or cattle skin membranes, applied successfully to all stages (larvae, nymphae and adults) of the ioxodid tick, amblyomma variegatum, is described. the feeding apparatus consisted of a blood container with a membrane placed on top of a tick containment unit. a carbon dioxide atmosphere of between 5 and 10% and a temperature of 37 degrees c were used as stimulants for the attachment of the ticks. high co2 concentrations in the atmosphere improved the feeding ...19938233589
antibodies to cowdria ruminantium in mozambican goats and cattle detected by immunofluorescence using endothelial cell culture antigen.endothelial cell cultures, established from bovine umbilical cord arteries and subsequently infected with cowdria ruminantium, were used as antigen in the indirect fluorescent antibody test. bovine sera (374) and caprine sera (388) collected in 6 provinces of mozambique were tested. overall, 30.4% of goat sera had antibodies to cowdria, and 43% of sera collected from cattle. north of the river save, where the tick amblyomma variegatum is highly prevalent, overall percentages of positive sera wer ...19938236490
cross-mating between amblyomma parvum aragao, 1908 and amblyomma pseudoparvum guglielmone, mangold et keirans, 1990 (acari: ixodidae). 19938244207
impact of natural infestation of amblyomma variegatum on the liveweight gain of male gudali cattle in adamawa (cameroon).the effect of natural tick infestation on the liveweight gain (lwg) of male gudali zebu cattle was studied throughout a year by comparing the performances of two herds, one of which was submitted to weekly acaricidal treatment and the other was left untreated against ticks. six species of ticks were identified on the untreated animals: amblyomma variegatum, boophilus decoloratus, rhipicephalus lunulatus, rhipicephalus turanicus, hyalomma nitidum and hyalomma marginatum rufipes. most of the losse ...19938249253
an immunoblotting diagnostic assay for heartwater based on the immunodominant 32-kilodalton protein of cowdria ruminantium detects false positives in field sera.heartwater, a major constraint to improved livestock production in zimbabwe, threatens to invade areas which have been previously unaffected. to monitor its spread in zimbabwe, an immunoblotting diagnostic assay based on the responses of animals to the immunodominant, conserved 32-kda protein of cowdria ruminantium was evaluated. in this assay, no false reactions were detected with sera known to be positive and negative, but sera from some cattle, sheep, and goats from heartwater-free areas of z ...19938253974
new version of lstsim for computer simulation of amblyomma americanum (acari: ixodidae) population dynamics.a previous version of lone star tick simulation model (lstsim) for a wildlife ecosystem was revised and expanded to include a beef cattle forage area and improved handling of tick-host-habitat interactions. relationships between environmental and biological variables were also refined in the new version. general validity of the revised model was established by comparing simulated and observed host-seeking populations of amblyomma americanum (l.) at five geographic locations, three in oklahoma an ...19938254630
ticks (acari: ixodidae) infesting medium-sized wild mammals in southwestern species of ixodid ticks (n = 2,661) were found on medium-sized wild mammals (n = 295) during a 13-mo study in shelby county, tennessee. the seven tick species collected were dermacentor variabilis (say), amblyomma americanum (l.), rhipicephalus sanguineus (latreille), ixodes texanus (banks), i. cookei (packard), i. scapularis (say), and haemaphysalis leporispalustris (packard). the raccoon had the greatest tick species diversity in all of the aforementioned ticks except h. leporispalustris ...19938254637
potential role of cattle egrets, bubulcus ibis (ciconiformes: ardeidae), in the dissemination of amblyomma variegatum (acari: ixodidae) in the eastern caribbean.the potential role of cattle egrets, bubulcus ibis (l.), in the dissemination of amblyomma variegatum (f.) in the eastern caribbean was evaluated. the status of cattle egrets as hosts for a. variegatum in antigua was determined during seven survey periods between september 1988 and may 1991. the mean prevalences of infestation by larvae and nymphs were 2.3 and 0.5%, respectively. the mean intensity and relative density of infestation by larvae were 8.8 (sd = 9.80) and 0.2 (sd = 0.28), respective ...19938271244
kinetics of male pheromone production by amblyomma variegatum (acari: ixodidae).males of amblyomma variegatum (f.), when attached on their host, produce a pheromonal blend composed of methyl salicylate, ortho-nitrophenol, and nonanoic acid, which acts as an aggregation-attachment pheromone. using olfactometry assays, assays on hosts, and quantification of the compounds by capillary gas chromatography, the kinetics of pheromone production has been studied. males engorged for at least 10 d elicit attachment from most of the tested females. attractiveness of males for females ...19938271253
changes in lipids of the salivary glands of the lone star tick, amblyomma americanum, during feeding.the lipid composition of salivary glands from male and female lone star ticks, amblyomma americanum, was investigated at progressive stages of tick feeding. the amounts of fatty acids from both phospholipid and neutral lipid fractions increased dramatically during the initial stage of feeding and peaked in partially fed females weighing 100-250 mg. percentage compositions of myristic (14:0) and palmitic acid (16:0) decreased, but stearic (18:0), oleic (18:1), linoleic (18:2), and arachidonic aci ...19938277375
first description of the male and redescription of the immature stages of amblyomma rotundatum (acari: ixodidae), a recently discovered tick in the u.s.a.the male of amblyomma rotundatum is described for the first time, and the nymph and larva are redescribed. this tick is a parthenogenetically reproducing species parasitic on amphibians and reptiles in the warmer areas of the new world. attempts to mate male and female a. rotundatum under laboratory conditions were unsuccessful.19938277377
analysis of lipids in the salivary glands of amblyomma americanum (l.): detection of a high level of arachidonic acid.analysis of lipids in salivary glands of the lone star tick, amblyomma americanum, demonstrated that arachidonic acid (20:4, n-6) comprises 8% of all fatty acids identified by gas chromatography. the occurrence of arachidonic acid and other c20 polyunsaturated fatty acids in tick salivary glands was confirmed by gas chromatography-mass spectrometry. arachidonate is located entirely in the phospholipid fraction and is associated exclusively with phosphatidylcholine (pc) and phosphatidylethanolami ...19938324244
isolation and transmission of the lyme disease spirochete from the southeastern united states.the isolation of the lyme disease spirochete (borrelia burgdorferi) from the southeastern united states is reported. three isolates, two from cotton mice (peromyscus gossypinus) and one from the black-legged tick (ixodes scapularis), were recovered from sapelo island, georgia, in july and september 1991. the spirochetes were characterized by indirect fluorescent antibody assay using a battery of five monoclonal antibodies, by sodium dodecyl sulfate/polyacrylamide gel electrophoresis (sds/page) o ...19938346258
amblyomma americanum: a potential vector of human ehrlichiosis.polymerase chain reaction primers specific for ehrlichia chaffeensis were used to amplify dna from extracts of pooled ticks. amplification was performed on extracts from 140 pools (1,579 total ticks) consisting of three tick genera collected from five states. the characteristic 389-basepair product was observed after amplification of extracts from seven different pools of adult amblyomma americanum (117 pools, 1,462 ticks), but not from pools of nymphs. no specific product was observed after amp ...19938357086
progress in research on tick-borne diseases: theileriosis and heartwater.the rapid population growth in subsaharan africa necessitates a great increase in animal production in the more humid zones. vector-borne diseases occurring in these zones will assume more importance, but are difficult to control. they include theileriosis and heartwater. recent developments in research on these diseases are presented. indigenous animal populations in endemic areas, subjected to natural selection, are far less susceptible than exotic stock. heartwater, caused by the rickettsia c ...19938372422
establishment of the foreign partheonogenetic tick amblyomma rotundatum (acari: ixodidae) in florida.the parthenogenetic tick amblyomma rotundatum, a central and south american species, has become established in southern florida. the date of introduction is unknown, but it is suspected to be either during the 1930s, when 1 of its natural hosts, the giant or marine toad, bufo marinus, was introduced to southern florida as a potential biological control of pest beetles in sugar cane fields, or between 1955 and 1964 when specimens of b. marinus were accidentally or deliberately released in the gre ...19938410557
detection of cowdria ruminantium by means of a dna probe, pcs20 in infected bont ticks, amblyomma hebraeum, the major vector of heartwater in southern africa.a dna probe, pcs20, previously described for use in detection of cowdria ruminantium infections in amblyomma variegatum (the principal vector of heartwater) hybridized with c. ruminantium dna in organs of laboratory-infected a. hebraeum adult ticks (the major southern african vector of heartwater). the probe hybridized with c. ruminantium dna in 46/49 midguts from male ticks and 26/29 from females, thus indicating infection. corresponding salivary glands were less heavily infected, but infection ...19938432329
implications of selection and hybridization studies on the mode of inheritance of photoperiodically induced developmental diapause in laboratory strains of the lone star tick (acari: ixodidae).selection of lone star ticks, amblyomma americanum (l.), that were reared in the laboratory under short-day photoperiods of 10:14 (l:d) h resulted in third generation (f3) diapause versus f3 nondiapause strain replete nymphs having significantly different mean molting times (days from detachment to ecdysis) of 100.9 versus 54.7 d, respectively; whereas, the f7 unselected laboratory control strain had an even smaller, significantly different mean molting time of 49.5 d. two hybrid crosses of f2 n ...19938433316
experiments on the relationship between feeding of the tick amblyomma variegatum (acari: ixodidae) and dermatophilosis skin disease in sheep.experiments on the systemic effect of feeding adult amblyomma variegatum (f.) on dermatophilosis caused by dermatophilus congolenis in six sheep were performed by feeding ticks at sites separate from sites of experimental infection with d. congolensis. comparisons were made with d. congolensis infections on six control sheep without ticks. tick-infested sheep developed chronic dermatophilosis lesions; tick-free sheep healed rapidly. on two tick-infested and two control sheep a chronological sequ ...19938433320
differential recognition of saliva antigens from the ixodid tick amblyomma hebraeum (acari: ixodidae) by sera from infested and immunized rabbits.we determined the protein composition and antigenic content of saliva from amblyomma hebraeum female ticks of different weight classes. the mean protein concentration of saliva of small partially fed ticks (< 100 mg) was 333 +/- 83 micrograms/ml and that of large partially fed ticks (150-420 mg) was 59 +/- 14 micrograms/ml. the reduction in concentration mostly was caused by the significantly higher fluid volume per minute secreted by large ticks. polypeptide analysis of saliva indicated the pre ...19938433335
effects of temperature on fecundity and viral replication in amblyomma cajennense (arachnida: ixodidae) infected with venezuelan equine encephalomyelitis assess how temperature affects fecundity and venezuelan equine encephalomyelitis (vee) viral replication in vee-infected amblyomma cajennense (f.), adult ticks were inoculated intracoelomically with either vee virus (i-a variant) or diluent. ticks were held at 19, 26, or 33 degrees c and tested for vee virus over 20 d. up to 10 pairs of ticks (1 female:1 male) from each temperature group were allowed to feed on guinea pigs on day 8 after inoculation. maximum titers did not differ significantl ...19938433340
parasitic arthropods of sympatric opossums, cotton rats, and cotton mice from merritt island, florida.six species of parasitic arthropods were collected from 12 opossums (didelphis virginiana), 8 species were obtained from 28 cotton rats (sigmodon hispidus), and 4 species were collected from 10 cotton mice (peromyscus gossypinus) from merritt island, brevard county, florida. the flea polygenis gwyni was the only parasite that infested all 3 host species, and it was present in very high densities (mean intensity = 73.7) on the opossums. the american dog tick, dermacentor variabilis, and the tropi ...19938459341
a comparison of field tick infestation on n'dama, zebu and n'dama x zebu crossbred cattle.tick burdens, estimated from cumulative tick counts, were determined on n'dama, zebu and f1 n'dama x zebu crossbred cattle. n'dama showed significantly fewer ticks than the zebu and f1 cattle (p < 0.001). a previous trypanosomosis infection did not affect tick burdens on the three genotypes. amblyomma variegatum had a prevalence of 84.8% and hyalomma spp. 15.2%, with the ratio similar on all cattle breeds. trypanosomosis infection increased the serological prevalence of anaplasma marginale in ze ...19938493760
ixodid ticks (acari: ixodidae) and livestock production: effect of varying acaricide treatments on ticks and productivity in east coast fever-immunized weaner and dairy a pilot trial to evaluate cost-effective methods of acaricide application, east coast fever-immunized weaner and dairy cattle were subjected to varying tick control regimens. all experimental cattle were maintained under the same extensive system of management. their monthly tick load, packed cell volumes, incidence of blood protozoans, weight changes, and daily milk production were noted. apart from rhipicephalus appendiculatus neumann, other tick species found in the study site were r. pulc ...19938510109
computer-controlled olfactometer system for studying behavioral responses of ticks to carbon olfactometer system that consisted of a laptop computer, a carbon dioxide analyzer, and an apparatus to control gas flows was designed to study ixodid tick behavioral responses to varying carbon dioxide (co2) concentrations. the system provided a method to regulate and measure stimulatory co2 concentrations (1-99 ppm) above ambient co2 background levels. adult amblyomma americanum (l.) and dermacentor variabilis (say) demonstrated behavioral responses to co2 concentrations as low as 9 ppm abo ...19938510116
recent acquisitions on tick and tick-borne disease resistance in n'dama (bos taurus) and gobra zebu (bos indicus) cattle.the use of disease resistant breeds is recognised as an economically realistic alternative to acaricide application and drug administration in tick and tick-borne disease control schemes. although resistance is mainly associated with zebu (bos indicus) breeds, studies carried out in the gambia show a higher resistance to ticks and tick-borne diseases in n'dama (bos taurus) than in gobra (b. indicus) cattle. tick resistance in n'dama breed appears to be effective against those species with long h ...19958532370
the relationship between tick (amblyomma hebraeum) infestation and immunity to heartwater (cowdria ruminantium infection) in calves in zimbabwe.the occurrence of endemic stability for heartwater (cowdria ruminantium infection) is a controversial issue, because the means by which young cattle and other neonatal ruminants become infected and acquire immunity to the disease have never been adequately explained. we conducted a study in a heartwater-endemic area in southeastern zimbabwe to investigate the relationships between calf immunity to c. ruminatium, infestations of the tick vector amblyomma hebraeum and dam, colostral and calf antib ...19958533273
some properties of the ecdysteroid receptor in the salivary gland of the ixodid tick, amblyomma hebraeum.salivary gland degeneration in ixodid ticks is triggered by an ecdysteroid hormone. we used [3h]ponasterone a (poa) as a specific ligand to detect the ecdysteroid receptor in the salivary glands of large, partially fed female ticks (amblyomma hebraeum koch; acari: ixodidae). binding of [3h]poa was thermolabile and sensitive to pronase, but not to dnase or rnase, indicating that the ligand binds to a protein. scatchard analysis of [3h]poa binding strongly suggested the presence of an ecdysteroid ...19958536946
physiological and nutritional responses of steers infested with varying densities of amblyomma americanum (acari: ixodidae).the effects of varying densities of lone star tick, amblyomma americanum (l.), on measured physiological parameters of beef cattle in a controlled environment was determined. steers were infested with either 0, 20, 60, or 120 pairs of adult ticks. heart rate, respiration, rectal temperature, fecal and urine excretions, and water and feed consumption were monitored daily. blood samples were taken every 3rd d to measure cortisol, total proteins, urea nitrogen, and glucose levels. hematocrits were ...19958537543
prostaglandin biosynthesis and subcellular localization of prostaglandin h synthase activity in the lone star tick, amblyomma americanum.we report on prostaglandin (pg) biosynthesis in the lone star tick, amblyomma americanum. in vitro preparations of whole female ticks and internal tissues were competent to biosynthesize four pgs: pga2/pgb2, pgd2, pge2, pgf2 alpha. pga2/pgb2 was the major product under optimal conditions. pg biosynthesis by whole tick and internal tissues were sensitive to incubation conditions including, protein concentration, time, temperature, ph, and presence of a co-factor cocktail composed of reduced gluta ...19958541884
the life-cycle of the bont tick amblyomma hebraeum in vitro.the life-cycle of the hard tick amblyomma hebraeum was completed in vitro by feeding all life-stages of the tick through silicone membranes on bovine blood from an abattoir. ticks were placed in a simple feeder membranes on bovine blood from an abattoir. ticks were placed in a simple feeder consisting of a honey jar containing the blood with a glass tube insert (o.d. 42 mm) across the end of which the membrane was stretched. this feeding unit was held in a water bath (38 degrees c). larvae and n ...19958550288
prevalence of rickettsia-like organisms and spotted fever group rickettsiae in ticks (acari: ixodidae) from zimbabwe.the prevalence of rickettsia-like organisms in ticks from zimbabwe was determined using the hemolymph test. amblyomma hebraeum had the highest prevalence of rickettsia-like organisms. other species with rickettsia-like organisms included amblyomma sparsum, amblyomma variegatum, hyalomma marginatum rufipes, ripicephalus simus, haemaphysalis leachi, amblyomma rhinocerotis, and hyalomma truncatum. ticks with no demonstrable rickettsia-like organisms infection were boophilus decoloratus, haemaphysal ...19958551500
field evaluation of deet and a piperidine repellent (ai3-37220) against amblyomma americanum (acari: ixodidae).repellent efficacy of deet (n,n-diethyl-3-methylbenzamide) and a piperidine, ai3-37220, was evaluated topically on human volunteers against lone star tick, amblyomma americanum (l.), nymphs and adults in the field. ai3-37220, at 0.5 mg/cm2, provided > 90% repellency against adult and nymphal ticks over a 6-h test period and showed significantly better repellent efficacy than deet. deet, at the same concentration, provided 85% repellency at 0 h and deteriorated to 55% repellency at 6 h.19958551512
serologic diagnosis of human monocytic ehrlichiosis by immunoblot analysis.human monocytic ehrlichiosis is caused by ehrlichia chaffeensis, an intracellular bacterium probably transmitted by the tick amblyomma americanum in the united states. despite its lack of specificity in discriminating among infections by closely related ehrlichia spp., immunofluorescence assay (ifa) is the most frequently used serological diagnostic method. to improve the specificity of the serological diagnosis, we compared antigenic profile of e. canis and e. chaffeensis antigen with homologou ...19948556515
clinical disorders observed in anteaters (myrmecophagidae, edentata) in captivity.the major health problems found in 103 captive lesser anteaters (tamandua tetradactyla) and giant anteaters (myrmecophaga tridactyla), family myrmecophagidae, are presented and correlated with management. the most common of 200 recorded clinical disorders involved the digestive system (26%), nutritional deficiency (20%), injury (15.5%), respiratory system (10%), skin (7%) and circulatory system (4.5%), but 13% of the cases were inconclusive. parasites were identified in 48.5% of faecal samples, ...19958560755
hemocytic rickettsia-like organisms in ticks: serologic reactivity with antisera to ehrlichiae and detection of dna of agent of human granulocytic ehrlichiosis by pcr.ixodid ticks were collected from connecticut, massachusetts, missouri, pennsylvania, rhode island, and british columbia (canada) during 1991 to 1994 to determine the prevalence of infection with hemocytic (blood cell), rickettsia-like organisms. hemolymph obtained from these ticks was analyzed by direct and indirect fluorescent antibody (fa) staining methods with dog, horse, or human sera containing antibodies to ehrlichia canis, ehrlichia equi, or rickettsia rickettsii. of the 693 nymphal and a ...19958567911
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
temporal association of amblyomma americanum with the presence of ehrlichia chaffeensis reactive antibodies in white-tailed deer.from 1981 through 1993, tick infestations and serum antibodies reactive to ehrlichia chaffeensis, the causative agent of human ehrlichiosis, were monitored among white-tailed deer (odocoileus virginianus) at whitehall experimental forest, clarke county, georgia (usa). neither ticks nor e. chaffeensis antibodies were detected during the first two years of the study. infestations of the lone star tick (amblyomma americanum), a suspected vector of e. chaffeensis, first were noted on deer in 1983. p ...19958583627
prevalence of antibodies to coxiella burnetti, rickettsia conorii, and rickettsia typhi in seven african countries.the prevalences of antibodies reactive with coxiella burnetti, rickettsia conorii, and rickettsia typhi were determined by indirect fluorescent antibody testing of sera from seven african countries. the seroprevalences of antibodies reactive with c. burnetti and r. conorii in countries from north africa were similar to those reported from southern europe. in countries of sub-saharan africa, the seroprevalence of antibodies reactive with c. burnetti varied greatly; the generally higher figures fo ...19958589132
ixodid ticks from panthers and bobcats in florida.ixodid ticks were present in all 189 samples examined from 53 florida panthers (felis concolor coryi, 104 collections) and 85 bobcats (felis rufus floridana) in florida (usa) between 1974 and 1991. we identified 3,251 ticks from panthers and 918 from bobcats. specimens of dermacentor variabilis, ixodes scapularis, i. affinis, amblyomma maculatum, and a. americanum were present on 49, 39, 17, seven, and two of the 53 florida panthers, respectively, and comprised 36%, 55%, 7%, 1%, and < 1% of the ...19958592378
propagation of the tick amblyomma variegatum in the caribbean.the tropical bont tick, amblyomma variegatum, is an african tick species which infests livestock and wildlife. it was probably introduced in the central eastern islands of the caribbean during the 18th or 19th century, with cattle shipped from senegal. in africa and the caribbean, this tick is a vector of heartwater (a rickettsial disease of ruminants) and is associated with acute dermatophilosis (a bacterial skin disease of animals). until 1948, only guadeloupe and the neighbouring islands of m ...19958593414
parasites of domestic and wild animals in south africa. xxxiii. ixodid ticks on scrub hares in the north-eastern regions of northern and eastern transvaal and of kwazulu-natal.ixodid ticks were collected from scrub hares (lepus saxatilis) at three localities. nine tick species were recovered from 24 hares examined at pafuri, kruger national park, northern transvaal. the most abundant and prevalent species were hyalomma truncatum, rhipicephalus kochi and a rhipicephalus species (near r. pravus). twelve tick species were collected from 120 scrub hares examined around skukuza, kruger national park, eastern transvaal. the immature stages of hyalomma truncatum were most ab ...19958600436
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
parasites of domestic and wild animals in south africa. xxxiv. arthropod parasites of nyalas in north-eastern kwazulu-natal.seventy-three nyalas (tragelaphus angasii) in the umfolozi, mkuzi and ndumu game reserves in northeastern kwazulu-natal were examined for arthropod parasites during 1983 and 1984. in addition, six animals were examined during 1994. ten ixodid tick species, two louse species and a louse fly species were recovered. the nyalas were good hosts of all stages of development of boophilus decoloratus, rhipicephalus appendiculatus and rhipicephalus muehlensi and the immature stages of amblyomma hebraeum ...19958628570
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
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
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
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
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
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
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
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
the seasonal occurrence of ticks (acari: ixodidae) on sheep and in the field in the judean area of israel.a 2 year survey of ixodid ticks in the judean area of israel between 1983 and 1985 showed that sheep were parasitized by the following species: rhipicephalus sanguineus group (30.6%), rhipicephalus bursa (25.3%), haemaphysalis cretica (20.5%), haemaphysalis otophila (20.1%) and hyalomma anatolicum excavatum (3.1%). three other species, hyalomma marginatum rufipes, boophilus annulatus and amblyomma lepidum were also present but in very low numbers. a total of 50,816 specimens (78.1% adult ticks) ...19968746133
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
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
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
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
amblyomma tick feeding in relation to host health.the tick amblyomma variegatum has been shown by field and controlled laboratory experiments to have a direct causal relationship with severe clinical dermatophilosis. the tick does not transmit the pathogen in the usual sense, either biologically or mechanically. the tick suppresses the immune system of the host, for unknown reasons, and this appears to enable the existing dermatophilosis to become a severe disease. there are other factors involved with the progression of dermatophilosis to clin ...19968809988
the pathogenesis of dermatophilosis.pathogen, host and environmental factors must be considered in order to understand the pathogenesis of dermatophilosis. a frequently cited sequence of events involves physical damage to the skin, bacterial multiplication in the epidermis, repeated cycles of invasion by hyphae, infiltration by neutrophils and exudate, regeneration of epidermis and reinvasion. this paper is concerned with pathogen driven mechanisms involved in the origin and development of dermatophilus congolensis infections. pri ...19968809989
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
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
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
an assessment of host resistance to ticks on cross-bred cattle in burundi.groups of cattle of four different cross-breeds (ankole x friesian, ankole x brown-swiss, ankole x guernsey, ankole x sahiwal) plus a group of pure ankole cattle were immunized against tick-borne diseases: east coast fever, using a theileria parva trivalent vaccine, and anaplasmosis, babesiosis and, subsequently, heartwater. with the exception of two small subgroups of ankole and ankole x sahiwal which were treated by weekly spraying using delnav, all the groups were exposed to natural field cha ...19968834737
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 life-cycle of amblyomma variegatum (acari: ixodidae): a literature synthesis with a view to modelling.all available information on the life-cycle of amblyomma variegatum is collated. data for each parameter are analysed to derive mathematical descriptions, which may now be used to construct a model of the life-cycle of this tick. areas for future research are identified. these include the collection of data for most parameters around threshold conditions to clarify discrepancies reported in the literature and to better quantify the relationships described, examination of the effects of photoperi ...19958847166
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
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
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
site-specific geographic association between amblyomma americanum (acari: ixodidae) infestations and ehrlichia chaffeensis-reactive (rickettsiales: ehrlichieae) antibodies in white-tailed deer.serum samples from white-tailed deer, odocoileus virginianus zimmermann, collected from 1982 through 1992 from the southeastern united states were tested for antibodies reactive to ehrlichia chaffeensis anderson, dawson, jones, & wilson, the causative agent of human ehrlichiosis. results were compared between areas based on known infestations of the lone star tick, amblyomma americanum l., a suspected vector of e. chaffeensis. one hundred and twenty-five of 300 (41.7%) deer tested positive (> or ...19968906920
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
human ehrlichiosis--maryland, 1994.ehrlichiosis is an emerging tickborne infectious disease caused by obligate intracellular, gram-negative rickettsia that infect leukocytes. human monocytic ehrlichiosis (hme) is caused by ehrlichia chaffeensis and is believed to be transmitted by amblyomma americanum (the lone star tick). most hme cases have been reported in southeastern and south-central states. during may-july 1994, five cases of serologically confirmed hme were identified among residents of maryland. all five persons lived ne ...19968926996
infestations of the bont tick amblyomma hebraeum (acari: ixodidae) on different breeds of cattle in zimbabwe.infestations of adults and nymphs of amblyomma hebraeum were counted on brahman (br), brahman x simmental (bs), sanga (sa) and hereford (he) steers exposed to infested pastures at mbizi in southern zimbabwe in 1986-1987. herefords were always the most heavily infested, while the sanga tended to carry the fewest ticks with the brahman and brahman x simmental groups being in between. the ratios of the engorged females on the four breeds were 2.3:1.4:1.4:1.0 for he:br:bs:sa. the ratios of the stand ...19968952073
proceedings of a workshop on the control of amblyomma variegatum and associated diseases. accra, ghana, 4 november 1994. 19968966770
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
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
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
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-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
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
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
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
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
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
Displaying items 601 - 700 of 1744