Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| travel medicine for the extreme traveler. | 0 | 17101310 | |
| update on tick-borne rickettsioses around the world: a geographic approach. | tick-borne rickettsioses are caused by obligate intracellular bacteria belonging to the spotted fever group of the genus rickettsia. these zoonoses are among the oldest known vector-borne diseases. however, in the past 25 years, the scope and importance of the recognized tick-associated rickettsial pathogens have increased dramatically, making this complex of diseases an ideal paradigm for the understanding of emerging and reemerging infections. several species of tick-borne rickettsiae that wer ... | 0 | 24092850 |
| arthropod surveillance programs: basic components, strategies, and analysis. | effective entomological surveillance planning stresses a careful consideration of methodology, trapping technologies, and analysis techniques. herein, the basic principles and technological components of arthropod surveillance plans are described, as promoted in the symposium "advancements in arthropod monitoring technology, techniques, and analysis" presented at the 58th annual meeting of the entomological society of america in san diego, ca. interdisciplinary examples of arthropod monitoring f ... | 0 | 26543242 |
| allocrine modulation of feeding behavior by the sex peptide of drosophila. | mating elicits a dramatic reprogramming of female behavior in numerous insect species. in drosophila, this postmating response (pmr) comprises increased egg-laying rate and reduced sexual receptivity and is controlled by the products of the male accessory glands, a family of approximately 80 small peptides transferred in the male seminal fluid . here, we show that copulation strongly stimulates female food intake. remarkably, this change is abolished if the males lack a single, small seminal pro ... | 0 | 16581515 |
| fever and malaise associated with a painful papule on the ankle. | 0 | 16424931 | |
| the distribution of rickettsia in the tissues of insects and arachnids. | in the absence of a satisfactory definition of rickettsia the observations herein recorded were arbitrarily limited to bacterium-like organisms which are intracellular and gram-negative. rickettsia of this type were found in the following species: amblyomma americana, amblyomma hebraeum, boophilus decoloratus, atomus sp., casinaria infesta, chrysopa oculata, ctenocephalus canis, dermacentor variabilis, lepisma saccharina, lucoppia curviseta, margaropus annulatus, margaropus annulatus australis, ... | 1923 | 19868737 |
| the bont tick (amblyomma hebraeum), exotic vector of heartwater found in the united states. | 1965 | 14323370 | |
| ticks in the south african zoological survey collection. 13. gynanders of boophilus decoloratus (koch, 1844) and amblyomma hebraeum koch, 1844. | 1967 | 5586994 | |
| eradication efforts against tropical bont tick, amblyomma variegatum, in the virgin islands. | 1969 | 5766830 | |
| arsenic resistance in species of multi-host ticks in the republic of south africa and swaziland. | a survey was made in the republic of south africa and swaziland to determine the incidence of arsenic resistance in multi-host ixodid ticks. arsenic resistant strains were found in the following species:- rihipicephalus appendiculatus, rhipicephalus evertsi, rhipicephalus capensis, amblyomma hebraeum and a species of hyalomma, tentatively identified as hyalomma rufipes. strains of haemaphysalis leachi, haemaphysalis silacea and ixodes pilosus were also tested. | 1975 | 1223285 |
| aggregation response of nymphs to pheromone(s) produced by males of the tick amblyomma hebraeum (koch). | 1976 | 1250397 | |
| na, k-atpase in the salivary gland of the ixodid tick amblyomma hebraeum (koch) and its relation to the process of fluid secretion. | total and ouabain-sensitive atpase activities were determined in the salivary glands of ticks throughout the feeding cycle. activities were very low in unfed specimens. in the glands of feeding females, the activities rose until a maximum was reached for both atpase components at approximately 200 mg. the activities remain low in males throughout the feeding period. these findings are discussed in relation to the fluid secretory process of the salivary glands. | 1976 | 133818 |
| resistance to toxaphene by the bont tick, amblyomma hebraeum (koch). | a series of in vitro and in vivo trials confirmed resistance by the three-host bont tick, amblyomma hebraeum (koch), to toxaphene in the cape, natal and transvaal provinces of the republic of south africa, and in swaziland and transkei. resistance was present in 80 of 97 field strains examined. lindane and ddt resistance was present in the one field strain tested. the results of comparative in vivo hand spraying and plunge dipping trials confirmed those of the larval in vitro tests, thus validat ... | 1977 | 874951 |
| ecology of the tick amblyomma hebraeum koch in the eastern cape province of south africa. i. distribution and seasonal activity. | in the eastern cape province of south africa larvae of amblyomma hebraeum koch occur in well-drained, shaded habitats, with a ground cover of grass. the life cycle is normally of 3 years duration. peak larval activity occurs in the summer of the 1st year, peak nymphal activity in the spring of the 2nd year, and peak adult activity in the summer of the 3rd year. larval activity shows no direct correlation with macroclimate. adult activity is correlated with, in the following order of signficance, ... | 1977 | 886412 |
| the influence of adrenergic agonists and their antagonists on isolated salivary glands of ixodid ticks. | various drugs elicit fluid secretion by isolated salivary glands of two species of ixodid ticks (dermacentor andersoni stiles and amblyomma hebraeum koch). among catecholamines, the following order of potency was observed: dopamine, epinine, noradrenaline = adrenaline and isoprenaline. the following drugs, in order of potency, were also agonists on this preparation: ergonovine, ergotamine, 6-hydroxydopamine, apomorphine, phenylephrine, norphenylephrine, beta-phenylethylamine, tyramine, d, l-dopa ... | 1977 | 891618 |
| evidence for an assembly pheromone(s) produced by males of the bont tick, amblyomma hebraeum (acarina: ixodidae). | 1977 | 903938 | |
| studies on the ecology of the tick amblyomma hebraeum koch in the eastern cape province of south africa. ii. survival and development. | quantitative data are given on the survival and rate of development of amblyomma hebraeum koch in relation to temperature and humidity, in laboratory and field conditions. by comparison with other ixodid species the developmental periods of a. hebraeum are extremely long. development is most rapid at 30 c, and the duration of the developmental periods increases exponentially with decreasing temperature. oviposition occurs successfully at 15 and 30 c, egg incubation at 20 to 30 c, and larval and ... | 1977 | 577931 |
| chemoreceptor organs used in detection of pheromone(s) of the tick amblyomma hebraeum (acarina: ixodidae). | 1977 | 609070 | |
| morphology of the spermatid and spermatozoon of amblyomma hebraeum koch (acarina; ixodidae). | spermatids and spermatozoa of amblyomma hebraeum were examined by scanning and transmission electron microscopy as well as by freeze-etch and freeze-fracture techniques. the external surface of the spermatid is smooth except for a rim of two parallel grooves near the anterior apex. this rim probably marks the level at which a cap detaches, permitting extrusion of the inner cord during spermatozoon maturation. both ends of the spermatid are closed, the anterior part being slightly thicker than th ... | 1978 | 654427 |
| actions of some transmitters and their antagonists on salivary secretion in a tick. | cholinomimetics (pilocarpine, carbachol, physostigmine, acetylcholine, acetyl-beta-methylcholine) and sympathomimetics (dopamine, epinephrine), when injected into the hemolymph, provoked salivary fluid secretion in the female ixodid tick amblyomma hebraeum koch. atropine, but not tubocurarine or toxiferine, abolished pilocarpine-induced secretion without reducing the response to dopamine. reserpine and guanethidine likewise selectively attenuated pilocarpine-induced secretion. following extirpat ... | 1978 | 677342 |
| the activity of insect juvenile hormone mimics in larval amblyomma hebraeum koch (acarina: metastriata: ixodidae). | a total of 14 insect juvenile hormone mimics was tested for activity in amblyomma hebraeum by exposing newly engorged larvae to filter paper impregnated with hormone mimics. the most active compounds used in this assay were hs 103 (6-ethyl-3-pyridyl geranyl ether; ec50=0,0018 mg/cm2), zr 512 (ethyl 3,7,11-trimethyldodeca-2,4-dienoate; ec50=0,0022 mg/cm2), hs 2 (6-methyl-3-pyridyl geranyl ether; ec50=0,0035 mg/cm2), zr 615 (n-ethyl 3,7,11-trimethyldodeca-2,4-dieneamide; ec50=0,0035 mg/cm2), zr 77 ... | 1978 | 704043 |
| repeated feeding of amblyomma herbraeum (acarina: ixodidae) immatures on laboratory hosts. host effects on tick yield, engorged weight and engorgement period. | rabbits and sheep are unable to acquire a resistance to larvae and nymphs of amblyomma hebraeum. after repeated infestation of hosts there is no progressive decline in either the tick yield or the engorged weight of fed ticks. seasonal fluctuations in engorged weights do occur however, with the weight declining in early to midwinter and increasing in early to midsummer. changes in hose physiology as a result of low temperature acclimatization appear to be responsible for the fluctuations. tick y ... | 1978 | 722460 |
| effects of 60co irradiation on amblyomma hebraeum koch, 1844 (acarina: ixodidae). | the effects of 60co irradiation on amblyomma hebraeum koch, 1844 were studied by mating normal females to males irradiated to attain dosages of 0, 2, 4, 6 and 8 kilorad. the males of all 5 groups were observed mating 7 days after being placed on the host. the higher the irradiation dosage received by the males, progressively longer were the feeding periods of the females mated with them and fewer completed their engorgement. furthermore, the mass of the females when engorged was lower, fewer lai ... | 1978 | 750959 |
| resistance to certain organophosphorus ixodicides in the bont tick, amblyomma hebraeum koch, in the republic of south africa and swaziland. | a series of in vitro trails confirmed resistance in the three-host tick, amblyomma hebraeum koch, to the organophosphorus ixodicides, dioxathion, chlorfenvinphos, quintiofos, bromophos-ethyl and a dioxathion/chlorfenvinphos combination. the results of a routine survey showed that a resistance factor of greater than 100x was present in the offspring of ticks in six of 115 field isolates tested. these six isolates were confined to the lowveld areas of the province of natal, republic of south afric ... | 1978 | 752082 |
| proteins and free amino acids in the salivary secretion and haemolymph of the tick amblyomma hebraeum. | electrophoretic and chromatographic separations of the salivary secretion of amblyomma hebraeum showed a less complex protein pattern than that of ornithodoros savignyi. a hyaluronidase active component was isolated. the haemolymph protein pattern showed a major protein fraction with a mobility slightly faster than that of bovine serum albumin. | 1978 | 754123 |
| parasites of domestic and wild animals in south africa. xiii. the seasonal incidence of adult ticks (acarina: ixodidae) on cattle in the northern transvaal. | ticks were collected over a period of 13 months, at approximately fortnightly intervals, from 6 africaner oxen kept on the farm nylsvley in the naboomspruit district. the 8 species of ixodidae collected were, in order of abundance, rhipicephalus appendiculatus, r. evertsi evertsi, hyalomma marginatum rufipes, h. truncatum, amblyomma hebraeum, r. simus, boophilus decoloratus and ixodes cavipalpus. the relative abundance of adult ticks of these species, their predilection feeding sites and seasona ... | 1979 | 460821 |
| a bioassay method for the pheromone(s) of the bont tick amblyomma hebraeum koch. | a bioassay was developed which enabled the detection of the pheromones of the bont tick (amblyomma hebraeum koch) within 2 hours with a reproducibility of 82 +/- 13%. dried, solvent-extracted ticks were glued onto the shaved backs of rabbits. those ticks to which pheromone extract was subsequently applied strongly attracted females of the same species. in a 2-way choice test a cork disc impregnated with pheromone extract was even more attractive to female ticks than a treated dried tick. | 1979 | 460823 |
| tick infestations and tick-borne diseases in zimbabwe rhodesia. | the distribution of tick species in zimbabwe rhodesia is significantly influenced by land utilization practices. the most commonly occurring species in the over-grazed tribal areas is boophilus decoloratus. by contrast, well-managed commercial farms and ranches support a wide range of tick species, the most important of which is rhipicephalus appendiculatus. until recently tick-borne diseases of cattle were efficiently controlled through dipping. the low incidence of disease was an important fac ... | 1979 | 553966 |
| properties of na, k-atpase from the salivary glands of the ixodid tick amblyomma hebraeum. | 1980 | 6253039 | |
| the effects of the tick amblyomma hebraeum (acari: ixodidae) on blood composition and weight of rabbits. | 1980 | 7218269 | |
| regulation of body volume by salivation in a tick challenged with fluid loads. | injection into the hemolymph of 1.2% nacl, 11.2% sucrose, 2.3% urea (all approximately isosmotic to hemolymph), or distilled water induced salivary fluid secretion in the ixodid tick amblyomma hebraeum koch. saline gave the largest response at high doses. injection of hyperosmotic nacl into the hemolymph did not induce salivation but led to the drinking of distilled water in amounts sufficient to dilute the salt load to isosmolarity. atropine only partially inhibited salivation induced by nacl, ... | 1980 | 7356041 |
| the ultrastructure of somatic neuromuscular junctions in the tick amblyomma variegatum (fabr.). | peripheral nerve axons synapse with somatic muscle fibres in the tropical bont tick amblyomma variegatum. each fibre is innervated by numerous terminals; some of the axons synapse more than once. the nerve terminals on coxal muscle fibres contain agranular electron lucent vesicles 50 to 58 nm in size and have the specialised synaptic membranes characteristic of chemically transmitting nerve-muscle junctions. some of the terminals on trochanteral muscle fibres additionally contain larger vesicles ... | 1980 | 7388905 |
| regional specialization of the sperm membrane in the tick amblyomma hebraeum koch (acari: ixodidae). | the spermatozoon of amblyomma hebraeum is about 200 micrometers long and comprises: (l)a thick, club-shaped anterior part, about 20 micrometers long bearing at its apex a "tactile" hemisphere, and (2) an elongated tail-like part, about 180 micrometers long. the surface of the "tactile" hemisphere is covered by numerous bulbous expansions, attached to it by short stalks. the base of the hemisphere is surrounded by a fringe of thin motile processes; the remaining surface of the spermatozoon is cov ... | 1980 | 7388929 |
| a critical evaluation of the role played by the red-billed oxpecker buphagus erythrorhynchus in the biological control of ticks. | buphagus erythrorhynchus uses 4 feeding methods--scissoring, plucking, pecking and insect catching. during the day the birds spend 68% of their time feeding, with peaks of activity during the early morning and late afternoon. a total of 21 641 ixodid ticks were found in 53 stomachs examined, with a range of between 16 and 1 665 per stomach. boophilus and rhipicephalus were the most important genera eaten. thirty diptera, also found in the stomachs, accounted for 0,4% of the diet by mass. the foo ... | 1980 | 7413164 |
| cattle ticks from the waterberg district of the transvaal. | macroscopically visible ticks were collected from the hides of 28 cattle slaughtered in pairs during a period of 14 months in the waterberg district. in order of prevalence rhipicephalus appendiculatus, rhipicephalus evertsi evertsi, amblyomma hebraeum, hyalomma marginatum rufipes, ixodes cavipalpus, hyalomma truncatum and boophilus decoloratus were recovered. immature stages of the three commonest species constituted a major portion of the population for varying periods during the months april ... | 1980 | 7452655 |
| some effects of 60co irradiation on cowdria ruminantium in its tick host amblyomma hebraeum koch (acarina: ixodidae). | an attempt was made to attenuate cowdria ruminantium by irradiation of the nymphal stage of its tick host, amblyomma hebraeum. the irradiated nymphs were homogenized and serial dilutions of the resultant suspension were injected intravenously into heartwater-susceptible sheep. no attenuation could be demonstrated but the results indicate that progressively more micro-organisms will be destroyed the higher the irradiation dosage applied, and that dosages between 20 and 30 kilorad apparently prove ... | 1981 | 7279384 |
| an investigation into the toxic principle in eggs of the tick amblyomma hebraeum. | a purification procedure involving iso-electric focusing by means of which a toxic principle may be obtained in a pure form from crude egg extracts of amblyomma hebraeum is described. the molecular mass of the toxin is approximately 10 000 according to sedimentation equilibrium sedimentation, sodium dodecyl sulphate (sds) gradient gel electrophoresis and calculations from the amino acid composition. non-competitive proteinase inhibitory activity was found to be associated with the toxin. histopa ... | 1981 | 7312303 |
| observations on the transmission of theileria mutans in south africa. | four isolates of theileria mutans obtained from geographically distant parts of south africa by subinoculation of infected blood were found to be readily transmitted by the bont tick amblyomma hebraeum. all attempts to transmit these isolates with rhipicephalus appendiculatus were unsuccessful. possible explanations for differences between these results and those reported by earlier workers in this country are discussed. | 1981 | 6792579 |
| potentiation by spiperone and other butyrophenones of fluid secretion by isolated salivary glands of ixodid ticks. | isolated salivary glands from the ixodid tick, amblyomma hebraeum koch are stimulated to secrete fluid when exposed to dopamine (da), the maximum response occurring at 10(-6) m. spiperone, and a number of other butyrophenone derivatives, although lacking intrinsic activity, are able to potentiate the secretion elicited by supramaximal concentrations of da; this potentiation by spiperone is evident at concentrations in the femtomolar range. tranylcypromine, a potent, competitive inhibitor of mono ... | 1981 | 6273183 |
| [experimental transmission of the yellow fever virus by the tick amblyomma variegatum (f.) (author's transl)]. | experimental transmission of the yellow fever virus by the tick amblyomma variegatum (f.) (the tropical bont tick) is demonstrated for the first time. the tick transmitted the virus from one monkey to another. trans-stasial passage from nymph to adult stage was also demonstrated. the possible role of amblyomma variegatum as a vector and a potential reservoir of yellow fever is discussed. | 1982 | 7105284 |
| comparative ultrastructure of the spermatids and spermatozoa of the tick hyalomma dromedarii and amblyomma hebraeum (acari: ixodidae). | 1982 | 7153570 | |
| parasites of domestic and wild animals in south africa. xv. the seasonal prevalence of ectoparasites on impala and cattle in the northern transvaal. | the prevalence of ectoparasites on a total of 36 impala (aepyceros melampus) slaughtered monthly from february 1975 to february 1976 and a total of 24 cattle slaughtered monthly from march 1976 to march 1977 in the nylsvley provincial nature reserve was determined. six species of ixodid ticks were collected from the impala and these, in order of abundance, were: rhipicephalus evertsi evertsi, rhipicephalus appe. diculatus, amblyomma hebraeum, boophilus decoloratus, ixodes cavipalpus and hyalomma ... | 1982 | 7177586 |
| a bioassay technique for the pheromone emitted by amblyomma hebraeum males. | attachment of amblyomma hebraeum females, either around feeding males or in areas in which extracts of fed males had previously been placed, was studied. the percentage attachment of female ticks around feeding males was significantly higher than that inside extract-treated areas. it was also found that the percentage attachment around the males increases with time, but there is little or no increase in attachment with time inside the treated areas. the amount of pheromone released by 1 feeding ... | 1983 | 6634086 |
| some helminth and arthropod parasites of the grey duiker, sylvicapra grimmia. | sixteen grey duikers were culled on the farm riekert 's laager in the central transvaal at irregular intervals from may 1979-march 1981. one trematode species, 3 cestode species and 16 nematode species were recovered from these animals. of these the following are new helminth records for this antelope: cooperia hungi , cooperia neitzi , cooperia pectinata , trichostrongylus axei, trichostrongylus colubriformis, trichostrongylus falculatus , trichostrongylus instabilis , impalaia tuberculata , ne ... | 1983 | 6676685 |
| evidence for multiple receptors mediating fluid secretion in salivary glands of ticks. | using isolated salivary glands of the ixodid tick amblyomma hebraeum koch, we tested the effectiveness of butaclamol and sulpiride in blocking fluid secretion stimulated by a number of agonists. (+)-butaclamol was a potent inhibitor of dopamine, n-methyldopamine and noradrenaline (ki congruent to 30-60 nm), but was less effective on ergometrine (ki congruent to 310 nm). tranylcypromine-stimulated fluid secretion in the absence and presence of (+)-butaclamol and (+/-)-sulpiride suggested that tra ... | 1983 | 6188618 |
| records of the bont tick, amblyomma hebraeum, from the angulate tortoise, chersina angulata, and the leopard tortoise, geochelone pardalis. | a. hebraeum nymphae were found on 4 angulate tortoises and 13 leopard tortoises in the addo elephant national park, eastern cape province. adults of this species were collected for the 1st time from a leopard tortoise in the mkuze game reserve, natal. the significance of this finding, in relation to the normal host preferences of this tick, is briefly discussed. | 1984 | 6533508 |
| efficacy of ivermectin against ectoparasites of cattle in south africa. | the efficacy of various formulations of ivermectin administered at the recommended dose rate of 200 micrograms/kg was evaluated in cattle infested with mange mites (sarcoptes scabiei var. bovis.), lice (linognathus vituli and damalinia bovis) and ticks (boophilus decoloratus, amblyomma hebraeum, rhipicephalus appendiculatus and hyalomma spp.) in 8 trials conducted in south africa. mange mites (s. scabiei) were eliminated from animals treated subcutaneously, resulting in marked clinical recovery. ... | 1985 | 3839021 |
| a method for determining the cowdria ruminantium infection rate of amblyomma hebraeum: effects in mice injected with tick homogenates. | amblyomma hebraeum ticks, collected in the field and individually homogenized, were injected into mice. thirteen out of 240 ticks were shown to be infected with the heartwater agent. antibodies against cowdria ruminantium were detected in the sera of the mice by means of the indirect fluorescent antibody test. giemsa-stained smears, prepared from the haemocytes of the ticks, revealed morphologically different forms of the heartwater agent. a strain of c. ruminantium, designated the welgevonden s ... | 1985 | 3900855 |
| ticks on livestock in st. lucia. | cattle, sheep, goats and horses were examined for ticks. over 95% of holstein cross-breeds, 28% of sheep (local mixed breeds) and 18% of goats (local mixed breeds) examined from 18 august to 4 september 1983 were infested with the southern cattle tick, boophilus microplus canestrini. about 90 and 17% of the horses examined were infested with the tropical horse tick, anocentor nitens neumann, and the tropical bont tick, amblyomma variegatum fabricius, respectively. the tropical bont tick was foun ... | 1985 | 4090245 |
| proof of transovarial transmission of cowdria ruminantium by amblyomma herbraeum. | transovarial transmission of cowdria ruminantium by amblyomma hebraeum does occur in certain instances. both the transovarial and the filial infection rates appear to be very low. the infection may reappear only in the adults or nymphae, or in all 3 stages of the tick's life cycle. | 1986 | 3960489 |
| the detection of antibodies to cowdria ruminantium in serum and c. ruminantium antigen in amblyomma hebraeum by an enzyme-linked immunosorbent assay. | a sensitive and reliable enzyme-linked immunosorbent assay for the detection of antibodies to cowdria ruminantium in serum and c. ruminantium antigen in amblyomma hebraeum nymphae is described. for the screening of antibodies, c. ruminantium from a. hebraeum nymphae, partially purified by wheat-germ lectin affinity chromatography, was used as antigen. to screen nymph populations, sera from either ball 3 strain-infected sheep or kumm-strain infected mice were used. by using appropriate controls t ... | 1986 | 3960490 |
| a comparison of the tick burdens of wild animals in a nature reserve and on an adjacent farm where tick control is practised. | acaricidal treatment of cattle, sheep and goats on a farm in valley bushveld in the grahamstown district resulted in a reduction in the numbers of certain tick species on kudu (tragelaphus strepsiceros), scrub hares (lepus saxatilis) and crowned guinea fowl (numida meleagris) on the same farm. the tick species most severely affected was amblyomma hebraeum, while haemaphysalis silacea, hyalomma marginatum rufipes and rhipicephalus appendiculatus were affected to a lesser extent. rhipicephalus gla ... | 1986 | 3572954 |
| the effect of avermectins on feeding, salivary fluid secretion, and fecundity in some ixodid ticks. | we tested the effects of the potent acaricides, avermectin b1a (avm) and 22,23-dihydroavermectin b1 (ivermectin; ivm) when injected directly into partially fed and fully engorged female ticks. when injected into small ticks (amblyomma hebraeum koch), neither drug (up to 100 micrograms/kg b.w.) inhibited subsequent engorgement nor affected oviposition latency, weight of total egg mass laid nor viability of laid eggs. at higher concentrations (1000 and 5000 micrograms/kg b.w.), avm and ivm were ma ... | 1986 | 3451859 |
| parasites of domestic and wild animals in south africa. xviii. the crowned guinea fowl (numida meleagris), an important host of immature ixodid ticks. | the tick burdens of 10 crowned guinea fowl (numida meleagris), shot at approximately 3-monthly intervals in the mountain zebra national park, and of 21 crowned guinea fowl from the andries vosloo kudu reserve, the majority of which were shot at monthly intervals, were determined. no adult ticks were recovered from any of the guinea fowl. the birds in the mountain zebra national park harboured 4 species of ixodid ticks of which amblyomma marmoreum was the most abundant and most prevalent. three b ... | 1986 | 3725331 |
| metabolism of [3h]ecdysone by isolated tissues of the female ixodid tick amblyomma hebraeum (ixodoidea; ixodidae). | malpighian tubules, gut, ovaries and carcasses of the adult female tick amblyomma hebraeum were incubated in vitro in the presence of 2 microm [3h]ecdysone. organs and media were separately extracted after 6, 24 and 48 h incubations and the patterns of ecdysone metabolites were analyzed by hplc. esterase-susceptible apolar metabolites similar to the ap2 already described in the soft tick ornithodoros moubata and thus presumably corresponding to the same conjugates (c-22 esters with fatty acids) ... | 1986 | 3758475 |
| isolation of cowdria ruminantium by means of percoll density gradient centrifugation and detection by an enzyme-linked immunosorbent assay. | the isolation of cowdria ruminantium by means of percoll density gradient centrifugation permits the recovery of partially purified viable populations of the organism possessing distinctly different densities. these conclusions are based upon results of analyses of density fractions by intravenous inoculation into sheep, protein determination, electron microscopy and enzyme-linked immunosorbent assay. morphological differences were observed in the density fractions obtained from infected brain t ... | 1986 | 3014417 |
| field sampling of unfed adults of amblyomma hebraeum koch. | no methods have previously been available for the field sampling of unfed adults of amblyomma hebraeum. we released 2000 unfed adults into a 5-m2 area in mopane woodland in southeastern zimbabwe. the ticks sought shelter beneath the debris on the soil surface but emerged and became active in host seeking when stimulated. effective stimuli were the odours of cattle and sheep and high concentrations of carbon dioxide from dry ice. the ticks did not respond to low concentrations of carbon dioxide, ... | 1987 | 3135161 |
| distinctive staining of colonies of cowdria ruminantium in midguts of amblyomma hebraeum. | mallory's phloxine-methylene blue stain was used to differentiate colonies of cowdria ruminantium in midgut epithelial cells of nymphal amblyomma hebraeum that had been infected as larvae. gut tissues were collected from nymphs that had fed on a susceptible sheep and were fixed in formol-saline on the day of repletion. paraffin sections, 3-4 micron thick, were then stained and this rendered colonies and cell nuclei densely blue against a uniformly pink background of tick tissues. colonies were e ... | 1987 | 2452397 |
| resistance of brahman and hereford cattle to african ticks with reference to serum gamma globulin levels and blood composition. | field collections of ticks from two breeds of cattle showed that the common species of ticks were amblyomma hebraeum, rhipicephalus appendiculatus and rhipicephalus evertsi evertsi. the density of these species was higher on hereford than on brahman cattle. the results also indicated that the density of immature stages of the above-mentioned ticks is higher on hereford than on brahman cattle. a positive correlation was found between the number of ticks on the cattle and the serum gamma globulin ... | 1987 | 2456184 |
| a comparison of live and destructive sampling methods of determining the size of a parasitic tick populations. | the accuracy of a general and a specific method of collecting and counting ixodid ticks on live hosts was compared with that of a destructive technique which can only be applied to dead animals. destructive sampling provided considerably more accurate results than either of the live sampling methods when applied to domestic goats (capra hircus) and a duiker (sylvicapra grimmia). the smaller the life stage and the tick species the less likely it is that it will be recovered by either of the live ... | 1987 | 3453335 |
| foot abscess in goats in relation to the seasonal abundance of adult amblyomma hebraeum and adult rhipicephalus glabroscutatum (acari: ixodidae). | the seasonal prevalence of foot abscess affecting angora and boer goats in valley bushveld in the eastern cape province of south africa was significantly related to the seasonal abundance of adult amblyomma hebraeum and adult rhipicephalus glabroscutatum. angora goats harboured more ticks than boer goats and also had a greater number of abscessed feet. larger numbers of ticks and abscesses were recorded on hind feet than on fore feet. there was no significant correlation between rainfall and the ... | 1987 | 3508202 |
| ultrastructural features of cowdria ruminantium in midgut epithelial cells and salivary glands of nymphal amblyomma hebraeum. | colonies of cowdria ruminantium were studied in midgut epithelial cells and salivary gland acini of nymphal amblyomma hebraeum that were infected experimentally as larvae. colonies were found in both tissues and studied with light and electron microscopy. colonies observed within gut cells frequently contained 2 types of the organism: electron-dense and reticulated forms. the morphology of colonies from salivary glands, as seen with light microscopy, varied from compact, densely-staining, small ... | 1987 | 3587934 |
| protection of cattle against heartwater in botswana: comparative efficacy of different methods against natural and blood-derived challenges. | five groups of tswana-cross castrated male cattle between 20 and 30 months of age (a total of 158 animals) were transported from a ranch in a heartwater-free area of south botswana to a feedlot near gaborone in the east of botswana where heartwater is endemic. on arrival, one group was vaccinated intravenously with the onderstepoort sheep blood heartwater vaccine, one group was vaccinated intravenously with the new onderstepoort tick-derived heartwater vaccine and a third group was vaccinated su ... | 1987 | 3604029 |
| metabolism of ecdysteroids in the female tick amblyomma hebraeum (ixodoidea, ixodidae): accumulation of free ecdysone and 20-hydroxyecdysone in the eggs. | [3h]-20-hydroxyecdysone ([3h]-20e) injected into amblyomma hebraeum females 7 days before the beginning of oviposition, viz. at the beginning of vitellogenesis, was converted to 3 polar peaks of unknown nature called 1, 2 and 3, and to apolar conjugates ap1, ap2 and ap3. ap2 have the same retention times as the esters of 20e with long chain fatty acids described in ornithodoros moubata (diehl et al. 1985). however, principally unmetabolized 20e was incorporated into the ovaries, and 16% of the i ... | 1987 | 3693624 |
| control of induced infestations of adult amblyomma hebraeum with sustained release ivermectin. | the efficacy of ivermectin, administered in a sustained release formulation by intraruminal pumps at approximate daily dose rates of 20, 40 and 60 micrograms/kg, was evaluated in 16 cattle against induced infestations of 3 strains of adult amblyomma hebraeum. engorged female ticks were mass-measured and incubated, and reproductive data recorded. there was an increase in mortality of male and female ticks compared to that of controls with increasing daily dose of ivermectin, and a decrease in the ... | 1987 | 3295646 |
| purification of cowdria ruminantium by density gradient centrifugation. | the isolation of cowdria ruminantium by differential and isopycnic density gradient centrifugation is reviewed with special reference to the suitability of percoll as density gradient medium. infected sheep brain, amblyomma hebraeum nymphae and various mouse organs were used as starting material. by these methods, partially purified viable populations of the organism with distinctly different densities were obtained. the conclusions are based upon results of analyses of density fractions by inoc ... | 1987 | 3329312 |
| purification of cowdria ruminantium by lectin cellular affinity chromatography. | this review covers the isolation of cowdria ruminantium by lectin cellular affinity chromatography from different amblyomma hebraeum sources. cellular affinity chromatography has been reviewed with special attention being given to the application of this technique in the isolation of rickettsiae. | 1987 | 3329313 |
| heartwater. the artificial transmission of cowdria ruminantium in domestic ruminants and mice. | the artificial transmission of cowdria ruminantium with infected blood, organ homogenates, peritoneal macrophages, tick stabilate and tissue culture cells is discussed. organ homogenates prepared from the myocardium, spleen, kidneys and liver of diseased animals are commonly used to infect mice. the efficacy of organ homogenates as a source of c. ruminantium depends on factors such as the route of inoculation and the heartwater isolate used. heartwater is artificially transmitted with infected t ... | 1987 | 3329318 |
| the ecology of the african vectors of heartwater, with particular reference to amblyomma hebraeum and amblyomma variegatum. | the hosts, sites of attachment, life cycle, habitat requirements and seasonal abundance of amblyomma astrion, amblyomma cohaerens, amblyomma gemma, amblyomma hebraeum, amblyomma lepidum, amblyomma marmoreum, amblyomma pomposum, amblyomma sparsum, amblyomma tholloni and amblyomma variegatum, the 10 potential vectors of heartwater in africa, are listed. factors influencing the distribution and abundance of the ticks as well as interactions with other species and the role of predators and pathogens ... | 1987 | 3329326 |
| some avian and mammalian hosts of amblyomma hebraeum and amblyomma marmoreum (acari: ixodidae). | large numbers of birds, wild mammals and domestic stock from a variety of localities within the republic of south africa were examined for infestation with the ixodid ticks amblyomma hebraeum and amblyomma marmoreum. every warthog (phacochoerus aethiopicus), burchell's zebra (equus burchelli), impala (aepyceros melampus) and kudu (tragelaphus strepsiceros) from the kruger national park in the north-eastern transvaal lowveld was infested with a. hebraeum. in the eastern cape province every helmet ... | 1987 | 3329327 |
| biochemical studies on the salivary glands and haemolymph of amblyomma hebraeum. | the functional significance of some components of salivary glands and of their secretion and of haemolymph of amblyomma hebraeum and other tick species is reviewed with respect to host responses at the attachment site, the survival of specific pathogens in the vector, the transmission of pathogens and immunological responses of the host to tick infestation. | 1987 | 3329330 |
| chemical control of the heartwater vectors. | this paper reviews available literature on the efficacy of acaricides against amblyomma hebraeum and other tick species, and presents information on tests done with registered chemicals in the laboratory. little published information is available on the efficacy of chemicals specifically against a. hebraeum. a host of formulations are registered for use as acaricides on cattle, sheep, and goats in south africa and thus, by implication, against this species. resistance has only been described to ... | 1987 | 3329335 |
| morphology and development of cowdria ruminantium in amblyomma ticks. | the morphology and development of cowdria ruminantium have been studied in amblyomma hebraeum and a. variegatum. colonies of c. ruminantium have so far been demonstrated microscopically in gut, salivary gland cells, haemocytes and malphighian tubules of infected amblyomma ticks. colonies in gut cells were seen in both unfed and feeding ticks but colonies in salivary gland acini were observed only in nymphs that had fed for 4 days. although the predominant type seen in both tick stages was the re ... | 1987 | 3448559 |
| problems with the interpretation of epidemiological data in heartwater: a study on 23 farms. | in an epidemiological study undertaken on 23 farms where heartwater occurs endemically, it was found that on an overall average, antibodies to cowdria ruminantium were detected in 64.3% of the cattle, 6 adult amblyomma hebraeum ticks were counted per animal and 7.0% of ticks were infected with the heartwater agent. it was found that the seropositivity of the animals was determined largely by the tick loads to which they were subjected and that the influence of the tick c. ruminantium infection r ... | 1987 | 3448573 |
| biochemical studies on the eggs of amblyomma hebraeum. | the isolation, characterization and kinetic properties of a toxic and non-toxic anti-protease from the eggs of a. hebraeum are compared with similar data obtained for eggs of other tick species. the biochemistry of various physiological processes in tick eggs is reviewed. | 1987 | 3448575 |
| the use of flumethrin 1% pour-on for the control of amblyomma spp. in various southern african countries. | efficacy trials with flumethrin 1% pour-on were conducted in 9 different areas in 3 southern and central african countries against amblyomma hebraeum and a. variegatum on cattle. a dose volume of 10 ml/100 kg body mass applied at bi-weekly intervals provided excellent control of both tick species on their predilection sites, irrespective of locally and seasonally high tick pressure. the trial results demonstrate clearly that this new concept of tick control can be effectively applied in commerci ... | 1987 | 3448582 |
| the effect of dipping on parasitic and free-living populations of amblyomma hebraeum on a farm and on an adjacent nature reserve. | domestic stock on a farm 30 km north of grahamstown were treated with an acaricide at regular intervals over a period of several years. this resulted in a marked reduction in all stages of development of amblyomma hebraeum on kudu (tragelaphus strepsiceros), scrub hares (lepus saxatilis) and helmeted guinea fowl (numida meleagris) which were on the farm compared with the burdens of similar animals in an adjacent nature reserve. the populations of free-living larvae of a. hebraeum on this farm an ... | 1987 | 3448583 |
| the developmental success of amblyomma hebraeum and amblyomma marmoreum on the leopard tortoise, geochelone pardalis. | the success of natural infestations of various life history stages of amblyomma hebraeum and amblyomma marmoreum on the leopard tortoise, geochelone pardalis, was compared. success was measured by the time taken for ticks to detach, as well as the percentage of ticks engorging and subsequently either moulting to the next life history stage or laying viable eggs. larvae of a. hebraeum were the only developmental stage not recovered. nymphae and female a. hebraeum were less successful in moulting ... | 1988 | 3353093 |
| the use of domestic chickens as laboratory hosts of the larvae of the bont tick, amblyomma hebraeum. | a comparison of attachment, engorgement and moulting success of amblyomma hebraeum larvae fed on domestic chickens and himalayan giant white rabbits indicates that chickens are better hosts than the rabbits. moreover the time needed for detachment of all engorged larvae is significantly less for chickens than for the rabbits. no evidence of induced immunity was found in chickens on re-infestation with larvae of a. hebraeum. | 1988 | 3353104 |
| kinetic properties of toxic protease inhibitors isolated from tick eggs. | 1. egg-toxins from rhipicephalus evertsi evertsi, boophilus microplus, boophilus decoloratus and hyalomma truncatum were found to be inhibitors of trypsin and in two cases also of chymotrypsin. 2. fast tight-binding and slow-binding inhibition were observed. 3. immunological identity of the toxins were assessed with ouchterlony immunodiffusion and elisa. 4. the protease content of b. decoloratus and amblyomma hebraeum tick eggs were determined by a linked enzyme assay. 5. the predictive value of ... | 1988 | 3391338 |
| field sampling of unfed nymphs of amblyomma hebraeum. | unfed nymphs of amblyomma hebraeum koch, 1844 shelter under debris on the soil surface and become active in host-seeking when stimulated with carbon dioxide. the active nymphs are not attracted to sources of carbon dioxide and hence cannot be effectively sampled using static carbon dioxide traps. however, these nymphs will cling to flannelette and can be sampled by flagging. larger numbers are recovered if the soil surface is sampled using a vacuum device. | 1988 | 3137010 |
| aggregation pheromones of the bont tick amblyomma hebraeum: identification of candidates for bioassay. | volatiles emitted by male amblyomma hebraeum while feeding on a rabbit were quantitatively sampled by the dynamic solvent effect and analysed by capillary gas-liquid chromatography and mass spectrometry. changes in emissions of 2-methyl propanoic acid, benzaldehyde and 2-nitrophenol paralleled reported increases in the attractiveness of males to conspecific ticks after 4-5 days of feeding. these compounds are therefore candidates for the bioassay of pheromonal activity. | 1988 | 3194113 |
| parasites of domestic and wild animals in south africa. xxiii. helminth and arthropod parasites of warthogs, phacochoerus aethiopicus, in the eastern transvaal lowveld. | a total of 69 warthogs, phacochoerus aethiopicus, were collected from 4 localities within the kruger national park, eastern transvaal lowveld. these animals harboured 16 nematode species, 2 trematodes, 1 or 2 species of adult cestodes and the larval stages of 4 cestodes. no pattern of seasonal abundance could be determined for any of the helminths. the warthogs were also infested with 3 flea species, 1 louse species, 8 ixodid tick species, 1 argasid tick and the nymphae of a pentastomid. the sea ... | 1988 | 3194114 |
| comparative feeding behaviour and food preferences of oxpeckers (buphagus erythrorhynchus and b. africanus) in captivity. | the feeding methods, activities and behaviour of red-billed and yellow-billed oxpeckers in captivity were compared. both species were found to be very similar with regard to feeding. the differences observed were a greater dependence on ectoparasites such as flies and larger ticks (amblyomma hebraeum) and a higher food intake for the yellow-billed oxpecker. these differences are the result of the larger size, limited choice of host animals and closer host/oxpecker relationship of the yellow-bill ... | 1988 | 3194119 |
| ability of adults of amblyomma hebraeum (acarina: ixodidae) to feed repeatedly on sheep and cattle. | adult amblyomma hebraeum ticks were exposed at 14-day intervals on five sheep on 46 occasions and on three cattle on 15 occasions to determine the effects of repeated feeding. the engorged weight and percentage of ticks which fed successfully on sheep declined significantly at first but subsequently they increased. on cattle there was no progressive decline in engorged weight, although the percentage which fed successfully declined significantly and was lower than that for sheep. this decline wa ... | 1988 | 3201710 |
| the treatment of ticks on tortoises using amitraz. | amitraz at a concentration of 2 ml litre-1 of water successfully induced detachment of amblyomma marmoreum and amblyomma hebraeum ticks from the mountain tortoise, geochelone pardalis. detached ticks died without reattaching. at the strength used, amitraz had no apparent adverse effects on the tortoises. | 1988 | 3210221 |
| the presence of cowdria ruminantium antigen in various tissues of amblyomma hebraeum imagines as detected by an enzyme-linked immunosorbent assay. | investigation into the presence of c. ruminantium antigen, using an enzyme-linked immunosorbent assay (elisa) in various tick tissues and haemolymph of adult amblyomma hebraeum ticks revealed that the organism invades a number of body parts and can be demonstrated in a. hebraeum. in females, the gut, salivary glands, hypodermis and synganglion and in males, the salivary glands and gut showed the highest concentration. | 1988 | 3217097 |
| experimental studies on the replication and transmission of crimean-congo hemorrhagic fever virus in some african tick species. | seven african tick species were studied as potential vectors of crimean-congo hemorrhagic fever (cchf) virus. engorged nymphae of 4 ixodid species, hyalomma marginatum rufipes, h. truncatum, rhipicephalus evertsi mimeticus, and amblyomma hebraeum, were inoculated intracoelomically with cchf virus and assayed for virus content at varying times post-inoculation. the virus replicated in all 4 species, reaching maximum titers of 4.6-5.5(10) fluorescence focus units per ml on days 5-9 post-inoculatio ... | 1989 | 2494900 |
| the role of males of the bont tick (amblyomma hebraeum) in the transmission of cowdria ruminantium (heartwater). | the role of males of the bont tick (amblyomma hebraeum) in the transmission of cowdria ruminantium (heartwater) was investigated. transstadial (nymph to adult) and intrastadial transmission were demonstrated. males transferred from live or dead hosts to live hosts were shown to transmit c. ruminantium repeatedly. it was concluded that male transmission is of importance in the epidemiology of heartwater. | 1989 | 2588467 |
| [the efficacy of alphamethrin-impregnated ear tags against ticks]. | the efficacy of 3 kinds of alphamethrin-impregnated ear tags was tested against natural amblyomma hebraeum, boophilus decoloratus, rhipicephalus appendiculatus, and rhipicephalus evertsi evertsi infestations of cattle. one type of ear tag was also tested in combination with a tail band of similar material. ticks were counted macroscopically on their predilection sites. counts of b. decoloratus, r. appendiculatus, and r. e. evertsi on all trial animals diminished steadily during the first 7d afte ... | 1989 | 2607535 |
| the carrier status of sheep, cattle and african buffalo recovered from heartwater. | sheep, cattle and the african buffalo (syncerus caffer) were shown to remain carriers of heart-water (caused by cowdria ruminantium) for long periods after recovery; 223, 246 and 161 days, respectively. transmission was achieved using adults of the southern african bont tick (amblyomma hebraeum) that had fed as nymphs on recovered animals. our findings differ from those of other workers who attempted transmission using nymphs that had fed as larvae on recovered animals or with blood from recover ... | 1989 | 2617830 |
| resistance of nguni, bonsmara and hereford cattle to ticks in a bushveld region of south africa. | counts of engorged female ticks on naturally infested cattle over a 2 year period, showed that indigenous nguni cattle harboured significantly fewer amblyomma hebraeum, boophilus decoloratus and hyalomma spp. during periods of peak abundance than either bonsmara or hereford cattle. fewer abscesses, associated with tick bite, were also present in the nguni cattle. individual tick resistance indices, determined after artificial tick infestation in the field, could not be correlated with hair lengt ... | 1989 | 2626263 |
| the host status of the striped mouse, rhabdomys pumilio, in relation to the tick vectors of heartwater in south africa. | striped mice, rhabdomys pumilio, were trapped over a 17 month period in the thomas baines nature reserve in the eastern cape province of south africa. captured mice were placed in cages, over water, and naturally detaching ticks were collected. only 5 larvae and 1 nymph of amblyomma hebraeum were recovered from the mice. these represented less than 0.1% of the total number of ticks recovered. no amblyomma marmoreum were recovered. as the vegetation and large mammals and tortoises in the thomas b ... | 1989 | 2626267 |
| spectral sensitivity, absolute threshold, and visual field of two tick species, hyalomma dromedarii and amblyomma variegatum. | 1. the spectral sensitivity in the wavelength range of 340-750 nm was determined by both a behavioral approach based on spontaneous positive phototaxis and the electroretinogram (erg). 2. concerning phototaxis the camel tick, hyalomma dromedarii, showed two sensitivity maxima, one in the uv range (ca. 380 nm) and another in the blue-green range (ca. 500 nm). at higher intensities the relative sensitivity was more pronounced in the uv and at lower intensities more pronounced in the blue-green (re ... | 1989 | 2746548 |
| the effect of the bont tick (amblyomma hebraeum) on the weight gain of africander steers. | the effects of the bont tick amblyomma hebraeum on the productivity of cattle need to be quantified in order to design economically optimal control programs. liveweight gains (lwgs) of three groups of africander steers, maintained in the same pasture and exposed to zero, medium or high numbers of larvae, nymphs and adults of the tick, were measured. larvae and nymphs had no significant effect on lwg but adults had a large, statistically significant effect (p less than 0.05). the tick-free group ... | 1989 | 2815542 |
| pheromone-mediation of host-selection in bont ticks (amblyomma hebraeum koch). | the bont tick, amblyomma hebraeum, is the principal vector to southern african ruminants of heartwater (cowdria ruminantium infection). the role of feeding male ticks, which emit an aggregation-attachment pheromone, in attracting unfed ticks to cattle was investigated. calves infested with feeding male ticks were more attractive to unfed adult ticks than were uninfested calves. the presence of the pheromone on previously infested cattle apparently allows unfed ticks to discriminate between hosts ... | 1989 | 2911745 |
| the impact of pure infestations of rhipicephalus appendiculatus and amblyomma hebraeum on the productivity of cattle and implications for tick control strategies in africa. | this paper reviews studies carried out by an fao project in zimbabwe, on the effects of the ticks rhipicephalus appendiculatus and amblyomma hebraeum on the productivity of cattle. larvae and nymphs of the two species had no detectable effect on liveweight gain (lwg). the losses in lwg caused by each adult female that completed feeding were approximately 4 g for r. appendiculatus and 10 g for a. hebraeum. losses in milk production caused by both species amounted to approximately 7 g for every fe ... | 1990 | 2126617 |
| organ culture of ixodid-tick salivary glands. | this work describes an organ-culture method for isolated salivary glands of the ixodid tick amblyomma hebraeum koch. the support medium is a tc 199-1% agarose gel with no hormonal or undefined supplements. i used a fluid-transport assay for measuring viability of salivary glands. when cultured at 26 degrees c, female glands secreted fluid at 65% on day 2, 59% on day 4 and 42% on day 6 post-culture compared to glands tested on day 0. fluid secretory rates in culture were higher than rates of glan ... | 1990 | 2226073 |
| effect of 20-hydroxyecdysone on the salivary glands of the male tick, amblyomma hebraeum. | female ticks (acari: ixodidae) feed only once in the adult stage, dying after laying a large batch of eggs. during the early post-engorgement stage, haemolymph ecdysteroid titre rises, which is probably responsible for autolysis of the salivary glands that takes place at this time. males, on the other hand, can re-attach and feed numerous times during the adult stage. males were fed on rabbits for either 7 or 14 days. haemolymph was collected either the day of removal from the host or 4 days lat ... | 1990 | 2226074 |
| efficacy of ivermectin delivered from an intraruminal sustained-release bolus against natural infestations of five african tick species on cattle. | the efficacy of ivermectin delivered by an orally administered prototype sustained-release bolus over approximately 90 days was evaluated against natural infestations of five african tick species. twenty cattle, allocated by restricted randomization based on counts of standard boophilus decoloratus, were allocated to two groups and were either given an ivermectin bolus or designated as non-medicated controls. all cattle grazed a single pasture of native grasses for 20-40 days before treatment an ... | 1990 | 2267728 |