increased pathogenicity of an ehrlichia-like agent after passage through amblyomma hebraeum: a preliminary report.after being passaged through 3 generations of amblyomma hebraeum, an ehrlichia-like agent isolated from an adult hyalomma truncatum female became more pathogenic and elicited a disease in sheep indistinguishable from heartwater. cross-immunity between this agent and several stocks of cowdria ruminantium and high levels of antibody elicited by the agent against 2 stocks of c. ruminantium in the indirect fluorescent antibody test, confirmed its close relationship to cowdria.19902293132
amblyomma americanum: identification of tick salivary gland antigens from unfed and early feeding females with comparisons to ixodes dammini and dermacentor variabilis.salivary gland antigens involved in host resistance to tick feeding by amblyomma americanum (lone star tick) have been identified. gland extracts from unfed and partially fed 12-, 48-, 72-, 96-, and 120-hr females and their corresponding midgut tissues were analyzed by immunoblotting with sera from naturally immune and hyperimmune sheep and rabbits. polypeptides at 90, 75, 58, 45, 33, and 23 kda from the salivary glands of a. americanum females were consistently observed with antibodies from bot ...19902298277
identification of babesia bovis and cowdria ruminantium on the island of unguja, zanzibar.babesia bovis and cowdria ruminantium were identified for the first time in cattle on unguja island, zanzibar. b bovis is common and widespread, although clinical disease had not been diagnosed previously. the vector of heartwater, amblyomma variegatum, is found throughout unguja but c ruminantium appears to be more localised in distribution than b bovis.19902301128
attempted transmission of ehrlichia risticii, causative agent of potomac horse fever, by the ticks, dermacentor variabilis, rhipicephalus sanguineus, ixodes scapularis and amblyomma americanum.dermacentor variabilis, rhipicephalus sanguineus, amblyomma americanum, and ixodes scapularis ticks were investigated for their ability to transmit potomac horse fever. larval and nymphal ticks were exposed to ehrlichia risticii by feeding on mice inoculated with the organism. molted exposed ticks were then allowed to feed on susceptible ponies or mice. no evidence of transmission, either clinically or by detection of antibodies to e. risticii in mice or ponies, was observed for any tick species ...19902307070
[interrelatio of acari ixodidae and hosts of edentata of the serra da canastra, minas gerais, brazil].we received for examination a small colection of ticks captured in the national park of the serra da canastra (mg), between 1979 and 1980. the authors demonstrated the existence of a broad co-accomodation of amblyomma pseudoconcolor on edentata of the family dasypodidae, being dasypodini the tribe more adjusted to this infestation. in conformity to the figs 1 and 2, dasypodini are probably the real hosts of a. pseudoconcolor and also the oldest hosts. for the first time, a. pseudoconcolor is als ...19892319951
ticks (acari: ixodidae) of the nile monitor on rusinga island, the course of a study of ticks of livestock, five nile monitor lizard specimens were caught and examined for ticks. although none of the tick species infesting livestock were found on the reptiles, a large number of adults and presumed nymphs and larvae of aponomma flavomaculatum (lucus) and adults of amblyomma sparsum (neumann) were collected. the ticks demonstrated a distinct predilection for their attachment sites. this is the second report of a. flavomaculatum from this part of kenya.19902332875
histological reactions to bites of amblyomma variagatum and rhipicephalus appendiculatus (acari: ixodidae) fed simultaneously on naive or sensitized rabbits.histopathological studies on attachment sites of nymphs, 48 h after attachment on three groups of rabbits, have revealed differences that were related to the rabbits' previous tick experience. feeding lesions caused by amblyomma variegatum (f.) in tick-naive rabbits were extensive and the total number of inflammatory cells was about 10 times greater than that in the feeding lesions caused by rhipicephalus appendiculatus neumann fed simultaneously on contralateral ears. rabbits that were previous ...19902332876
resistance of brahman and simmentaler cattle to southern african ticks.field collections of ticks from two breeds of cattle in the north western transvaal showed the common tick species to be rhipicephalus appendiculatus, amblyomma hebraeum, rhipicephalus evertsi evertsi and hyalomma marginatum rufipes. the number of these ticks was higher on simmentaler than on brahman cattle. correlation was found between the number of ticks on the cattle and their serum gamma globulin levels indicating an increase in the production of antibodies. similar correlation was also fou ...19902339000
ecological aspects of four species of ticks found on cattle in salta, northwest argentina.the seasonal activity of amblyomma cajennense, amblyomma neumanni, amblyomma parvum and boophilus microplus on cattle was studied in a ranch located in the northern part of the phytogeographical district of the chaco serrano where the habitat had suffered minimal human disturbance. the female ticks on one side of 10-25 cows were counted at intervals of 20-50 days from 29 october 1985 to 5 november 1986. the percentage of cattle parasitized with larvae and nymphs of amblyomma was recorded, along ...19902343535
ecology and phenology of cattle ticks in zambia: development and survival of free-living stages.a study on development and survival of free-living stages of three important cattle ticks in zambia, amblyomma variegatum fabricus, boophilus decoloratus koch, and rhipicephalus appendiculatus neumann, was carried out to complement studies on seasonal dynamics of parasitic stages. different instars of engorged ticks were exposed under quasi-natural conditions according to the season in which they occur naturally. generally, development rates of all stages of the three species were related to tem ...19902350995
experimental transmission of a granulocytic form of the tribe ehrlichieae by dermacentor variabilis and amblyomma americanum to dogs.transstadial transmission of granulocytic ehrlichieae in dogs was attempted using ticks, amblyomma americanum and dermacentor variabilis. ticks were exposed by feeding as nymphs on acutely infected pups; adult ticks then fed to repletion on susceptible adult dogs that were monitored daily for signs of infection. evidence of transmission was not observed in control dogs or in those exposed to d variabilis. in contrast, dogs exposed to a americanum developed serologic or clinical evidence of infec ...19902368951
rickettsia in texas.since the first reported case in 1941, rocky mountain spotted fever in humans has been reported from many areas of texas, with two major foci, one located in the north-central region and the other in the eastern region of the state. during the period 1979-1988, 421 cases of rmsf were reported, reaching 108 cases in 1983 and declining in subsequent years. statewide surveillance programs to detect spotted fever group rickettsiae in tick populations were initiated in 1976. in recent years, the sfg ...19902378448
ectoparasitic and phoretic arthropods of virginia opossums (didelphis virginiana) in central tennessee.thirteen species of ectoparasitic (12) or phoretic (1) arthropods were collected from 26 adult virginia opossums, didelphis virginiana, live-trapped from april through september 1987 in davidson county, tennessee. the cat flea ctenocephalides felis and the american dog tick dermacentor variabilis were the predominant species with respect to mean intensity and prevalence. the macronyssid mite ornithonyssus wernecki and the atopomelid mite didelphilichus serrifer, both specific parasites of this h ...19902380870
effects of sequential infestations of dermacentor albipictus and amblyomma americanum (acari: ixodidae) on overwintering beef cows in west-central texas.infestations of winter ticks, dermacentor albipictus (packard), observed on mature black angus cows, reached peak levels in january and diminished through march. infestations of adult lone star ticks, amblyomma americanum (l.), began in mid-january and increased through may. cows receiving ectrin, taktic, or deltox treatments on 13 december and 21 february experienced significantly less weight loss and entered the subsequent breeding season with higher average body weight than untreated cows. in ...19902388237
intrinsic competence of three ixodid ticks (acari) as vectors of the lyme disease spirochete.we compared the intrinsic vector competence of ixodes dammini spielman et al., dermacentor variabilis (say), and amblyomma americanum (l.) for the lyme disease spirochete (borrelia burgdorferi johnson et al.) on prudence island, rhode island, a lyme disease-endemic site where all three ticks occur together. natural and experimental spirochete infection rates were determined in those ticks and their degree of contact with white-footed mice (peromyscus leucopus), the principal reservoir host, was ...19902388239
infection rates with cowdria ruminantium of nymphs and adults of the bont tick amblyomma hebraeum collected in the field in zimbabwe.cowdria ruminantium (heatwater) infection rates of field populations of the bont tick, amblyomma hebraeum, were determined at two locations in the southern lowveld of zimbabwe. at mbizi quarantine station, unfed adult males and females, and nymphs were collected at intervals over a 2-year period using traps. at lemco ranch, engorged nymphs were collected on three occasions from weaner calves and allowed to moult to adults. the unfed ticks were fed in small pools on heartwater-susceptible sheep, ...19902399648
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 ...19872452397
western blot analysis of amblyomma americanum-derived stage-specific and shared antigens using serum from guinea pigs expressing resistance.serum from guinea pigs expressing resistance to larval, nymphal and adult amblyomma americanum ticks was used in western blot analyses to identify potential antigens from egg, larval and nymphal, and female salivary gland extract preparations. the results demonstrate multiple antigens unique to each life stage, as well as several shared proteins between the three life stages. however, it appears as if two particular proteins of 25 and 38 kda may be more important than others, based upon their pr ...19882455376
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 ...19872456184
[dermatophilus congolensis bovine dermatophilosis in the french west indies. iii. a comparison between infected and non-infected cattle].the determination of the distinctive features between infected and uninfected cattle by dermatophilus has been performed among 93 bovine stock in la martinique, and 120 in la guadeloupe and saint-martin islands. nearly half of the herds had been or were infected. morbidity rates reach 33 per cent in la martinique and 29 per cent in la guadeloupe with a mortality ratio of 15 per cent and 5 per cent respectively. no frequency difference could be observed with respect to the season or the geographi ...19892485539
experimental studies on the replication and transmission of crimean-congo hemorrhagic fever virus in some african tick 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 ...19892494900
experimental infection of six species of ixodid ticks with dugbe virus (family bunyaviridae, genus nairovirus).the vector potential of each of 6 species of colonized north american and african ixodid ticks was assessed by intracoelomic inoculation with dugbe virus (ibar 1792, 14th passage in suckling mouse brain) and viral titers were monitored after selected incubation periods. persistence of dugbe virus for greater than or equal to 53 days in 5 species (dermacentor andersoni, d. variabilis, amblyomma americanum, rhipicephalus appendiculatus, and r. sanguineus) indicates that infection occurred. viral t ...19892496609
ectoparasitic acari found on golden lion tamarins (leontopithecus rosalia rosalia) from brazil.anesthetized golden lion tamarins (leontopithecus rosalia rosalia), a highly endangered species, were examined for ectoparasites by brushing the fur and swabbing the ears. ectoparasites recovered from the fur included four species of immature ticks (amblyomma spp.), three species of chiggers (euschoengastia sp., microtrombicula brennani and speleocola tamarina), and one species of follicular mite (rhyncoptes anastosi). ectoparasites do not seem to be of particular significance to the health of t ...19892503627
difference in vector competence of two species of sympatric ticks, amblyomma variegatum and rhipicephalus appendiculatus, for dugbe virus (nairovirus, bunyaviridae).amblyomma variegatum was shown to be a competent vector of dugbe (dug) virus whereas rhipicephalus appendiculatus was not. when dug virus was taken up orally by a. variegatum nymphs, during capillary feeding, the virus replicated and persisted through moulting to the following adult stage. in contrast, although dug virus replicated in capillary fed r. appendiculatus nymphs, the virus did not persist trans-stadially into the adult stage. if the oral route of infection was by-passed by direct inoc ...19892510418
vector capacity of rhipicephalus appendiculatus and amblyomma variegatum for thogoto and dhori viruses.experimental studies were undertaken to ascertain the vector potential of rhipicephalus appendiculatus neumann and amblyomma variegatum fabricius for thogoto (tho) and dhori (dho) viruses, candidate members of the orthomyxoviridae. in the first set of experiments, ticks were infected orally by feeding on viraemic hamsters. tho virus replicated in r. appendiculatus and a. variegatum, persisted trans-stadially in both tick species, and was transmitted to susceptible hosts during feeding. in contra ...19892519663
ecological aspects of cattle tick control in central ecological studies in central zambia, both climate and ecotype affected population dynamics of tick species. below average rainfall for several years caused a suppression in numbers of rhipicephalus appendiculatus neumann adults. reduction in rainfall leading to changes in grazing patterns is thought to have been responsible for an increase in numbers of amblyomma variegatum fabricius adults in a grassland habitat. there were reasonable correlations between numbers of each tick species on ind ...19892519677
effect of tick control on liveweight gain of cattle in central zambia.field trials were carried out during 1982-86 in two different ecotypes in central zambia to determine the impact of tick control on the liveweight gain (lwg) of cattle. during the first 2 years of the trial a diamidide acaricide (amitraz) sprayed at weekly intervals caused periodic depression in lwg in young animals. thereafter a pyrethroid acaricide (cypermethrin) was used. during the 1984-85 tick season infestations of 50-120 adult amblyomma variegatum fabricius in untreated animals caused sig ...19892519678
resistance and cross-resistance in guinea-pigs and rabbits to immature stages of ixodid ticks.infestation of guinea-pigs and rabbits with larvae of any one of five species of ticks, rhipicephalus appendiculatus neumann, rhipicephalus evertsi evertsi neumann, amblyomma hebrauem koch, amblyomma variegatum fabricius and ixodes ricinus l., conferred resistance in the animals when exposed to subsequent infestations with the same tick species. resistance to infestations by other tick species was not observed.19892519683
rejection of ticks from guinea pigs by anti-hapten-antibody-mediated degranulation of basophils at cutaneous basophil hypersensitivity sites: role of mediators other than histamine.previous studies have established that recruitment of basophils to sites of tick feeding in guinea pigs is required to effect immune resistance. in the current study, actively sensitized guinea pigs treated three times daily with h-1 (mepyramine) and h-2 (cimetidine) histamine receptor antagonists, during the challenge tick infestation period, expressed normal resistance to amblyomma americanum larvae. similarly, naive guinea pigs treated with anti-histamines four times daily, beginning 7 days b ...19852578152
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.19892588467
control of lone star ticks (acari: ixodidae) on spanish goats and white-tailed deer with orally administered ivermectin.ivermectin administered orally to spanish goats, capra hircus (l.), or to white-tailed deer, odocoileus virginianus (zimmerman), was highly effective against lone star ticks, amblyomma americanum (l.). for spanish goats, daily oral doses of 20 micrograms/kg resulted in greater than or equal to 2 ppb ivermectin in the blood. this level was sufficient to cause greater than 95% reduction of estimated larvae from feeding ticks. a bioassay with horn flies, haematobia irritans (l.), was developed to e ...19892607030
[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 ...19892607535
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 ...19892617830
parasite survey of eight wild animals in the ruma national park.eight game animals representing seven species in the ruma national park in south nyanza, kenya, were examined for the presence of blood protozoa, ectoparasites, and helminthic and coccidian endoparasites using standard parasite-identification methods. haematological parameters were also determined. the oribi was positive for trypanosoma brucei ssp. and the reedbuck for t. congolense. no other blood protozoans were found. strongyle eggs were found in the faeces of all species except the water buc ...19892619384
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 ...19892626263
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 ...19892626267
transmission of lyme disease spirochetes (borrelia burgdorferi).the field and laboratory evidence incriminating nymphal ixodes dammini as the main vectors of borrelia burgdorferi is substantial. furthermore, other members of the ixodes (ixodes) ricinus 'complex', including i. ricinus, i. persulcatus, i. pacificus, and i. scapularis, are competent vectors of the lyme disease spirochete. although ticks in other genera are also naturally infected with b. burgdorferi, experimental evidence suggests that amblyomma and dermacentor ticks are inefficient vectors of ...19892667921
[the coevolution of ixodid ticks and terrestrial vertebrates].paleontologic and zoogeographic data speak in favour of mesozoic origin of ixodid ticks. the absence of strict restrictions for the feeding on unusual species of hosts has caused the domination of polyphagy and oligophagy over monophagy among ixodid ticks. the same peculiarities of ixodid ecology are responsible for a restricted part or absence of phylogenetic parallelism with hosts in their evolution. primary food relations with reptiles are, apparently, preserved only in the genus aponomma and ...19892694077
a mouse lethal dose assay for detection and titration of cowdria ruminantium (kwanyanga strain) in goats and ticks.a mouse lethal dose assay was used to detect a mouse pathogenic strain (kwanyanga) of cowdria ruminantium, the etiological agent of heartwater in goats and ticks. the titer of the rickettsial organisms in goat blood was directly related to the febrile response of the goat and the rickettsia were undetectable after the fever subsided. the maximum rickettsial titer in goat blood was 10(3) mouse ld50 ml-1. cowdria-infected goat blood was shown to retain infectivity when held on ice for up to 2 h, b ...19892705290
evaluation of the eradication program for amblyomma variegatum (acari:ixodidae) on puerto rico.a cooperative effort between the united states department of agriculture, animal and plant health inspection service, veterinary services, the agricultural research service, and the department of agriculture, commonwealth government of puerto rico has been successful in eradicating amblyomma variegatum (fabricius) from the islands of puerto rico and vieques (an island municipality of puerto rico). application of acaricides to livestock and dogs at 14-day intervals for an 18-month period eliminat ...19892707108
sites of attachment and density assessment in amblyomma americanum (acari: ixodidae) on nursing beef calves.primary attachment sites of male, female, and nymphal amblyomma americanum (l.) on nursing beef calves were the axillary, inguinal and perianal areas of the body. about 50% of all larvae fed on the ears. a density assessment method which uses the number of a. americanum on less than or equal to 5 body areas to predict the total number of ticks (tick burden) on the left side of a calf is presented. estimates of tick burden for male, female, nymphal and larval a. americanum each require examinatio ...19892714123
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 ...19892746548
habitat use by cattle affects host contact with lone star ticks (acari: ixodidae).the location of zebu, british, and zebu x british cattle in tick-infested plots from march through september 1986 was compared with the location of amblyomma americanum l. in the same plots. in april, may, and june, zebu cattle spent less time (9.3-19.4%) in tick-infested quadrats than british (44.4-63.9%) or zebu-british (49.0-69.3%) cattle. in the same months, the probability that a. americanum would contact zebu cattle (1.5-19.6%) was significantly lower than for british (34.7-41.7%) or zebu- ...19892754101
characterization of ixodid tick salivary-gland gene products, using recombinant dna technology.ticks secrete an array of lesion-maintenance factors into the host via the salivary glands while feeding, some of which elicit an immune response by the host that adversely affects the ability of the tick to feed and reproduce. our approach to characterizing these factors has been to make expression libraries from mrna of salivary glands (from unfed and 3-day-feeding amblyomma americanum females) which will serve as sources of the genes (clones) that code for them. thus far, we have detected 10 ...19892758938
acquired resistance to ixodid ticks induced by tick cement antigen.antisera from guinea pigs made resistant to infestation with an ixodid tick of east and central africa, rhipicephalus appendiculatus, were used to identify the tick antigens they recognized by immunoblotting. most of the antigens were found in tick salivary glands and in tick attachment cement. antisera from r. appendiculatus-resistant guinea pigs also recognized some salivary-gland antigens in ticks of other species (r. pulchellus, r. evertsi, amblyomma variegatum and a. gemma). antibodies agai ...19892758939
amblyomma variegatum ticks and the occurrence of bovine streptothricosis in antigua.the association between the occurrence of amblyomma variegatum ticks and streptothricosis was studied on the caribbean island of antigua. the prevalence of streptothricosis was higher on animals having a. variegatum ticks compared to that of animals not infested with a. variegatum ticks. there was a steady increase in the prevalence of severe lesions as the level of infestation with adult a. variegatum ticks increased. however the distribution of skin lesions could not be related to the predilec ...19892763757
monitoring of naturally acquired and artificially induced immunity to amblyomma variegatum and rhipicephalus appendiculatus ticks under field and laboratory conditions.the ability of rabbits, goats and cattle to acquire immunity to the ixodid ticks amblyomma variegatum and rhipicephalus appendiculatus was studied under laboratory and field conditions. rabbits were successfully immunized with crude salivary gland extract (sge) and midgut extract (me) obtained from flat or partly fed female r. appendiculatus ticks. the lowest numbers of larvae were produced by females fed on rabbits immunized with unfed midgut extract. similar reductions in larval production cou ...19892766896
polyfluoro 1,3-diketones as systemic insecticides.a series of aryl polyfluoro 1,3-diketones were examined for systemic ectoparasiticidal activity in cattle. the compounds demonstrated efficacy against several economically important species of insects and acarina. at dosages of 5 mg/kg x1 or 0.35 mg/kg per day intraruminally, activity was observed against blowfly larvae (phormia regina), adult stable fly (stomoxys calcitrans), and lone star tick (amblyomma americanum). in vivo activity was not directly related to in vitro activity, showing a str ...19892769686
female mediation of feeding time on cattle in adult lone star ticks (acari: ixodidae).the extended feeding time response on cattle of adult lone star ticks, amblyomma americanum (l.), during november through december is facultative and is mediated by the female. mean feeding time (11.8 d) in female ticks taken from the field and held at 14:10 (l:d) photoperiod and 25 degrees c for greater than or equal to 15 d was significantly shorter (p = 0.05) than for females taken directly from the field and fed on cattle (14.6 d). mean feeding times of females from the field paired to males ...19892769719
dugbe virus replication in nymph and adult amblyomma variegatum. 19892772415
delayed-type hypersensitivity test for assessing tick-immune status of cattle in zambia.delayed-type hypersensitivity skin reactions were used to assess the tick resistance status of tonga calves in zambia. the antigen used in the tests was a homogenate of unfed nymphal rhipicephalus appendiculatus which had been shown to give protective immunity in guinea pigs to adult female r appendiculatus. there was a significant negative correlation between the intensity of the reactions and the total number of ticks (amblyomma variegatum, r appendiculatus, hyalomma truncatum, boophilus decol ...19892773195
pericarditis associated with tick-borne q fever.a case of pericarditis associated with q fever is described. transmission was probably via an arthropod vector, which was most likely the kangaroo tick amblyomma triguttatum. complete recovery occurred in association with the use of non-steroidal anti-inflammatory agents only. this is a rare presentation of q fever implicating transmission by a novel vector.19892775046
pictorial key to the adults of hard ticks, family ixodidae (ixodida: ixodoidea), east of the mississippi river.six genera and 27 species of hard ticks (ixodidae) currently are recognized in the united states east of the mississippi river as follows: amblyomma (4 species), boophilus (1), dermacentor (3), haemaphysalis (2), ixodes (16), and rhipicephalus (1). we present a diagrammatic couplet key to the adults of the six genera and 27 species of ixodidae found in the eastern portion of the united states.19892795615
reduction of the amblyomma americanum (acari: ixodidae) population at fort a.p. hill, virginia, by aerial application of diazinon granules: correlation of percentage control with received dose.habitat (280 ha) of lone star tick, amblyomma americanum (l.), was aerially treated with 14% diazinon granules. concentration of acaricide reaching the forest floor ranged from 0.02 to 1.25 kg (ai)/ha. greater than 85% control was achieved at study plots receiving the highest dose. a positive correlation was shown between dose received at the forest floor and percentage of control of adults (r = 0.91) and nymphs (r = 0.86).19892795622
comparison of flagging, walking, trapping, and collecting from hosts as sampling methods for northern deer ticks, ixodes dammini, and lone-star ticks, amblyomma americanum (acari:ixodidae).ticks were sampled by flagging, collecting from the investigator's clothing (walking samples), trapping with dry-ice bait, and collecting from mammal hosts on fire island, ny, u.s.a. the habitat distribution of adult deer ticks, ixodes dammini, was the same in simultaneous collections from the investigator's clothing and from muslin flags. walking and flagging samples can both be biased by differences between investigators, so the same person should do comparative samples whenever possible. walk ...19892806016
amblyomma marmoreum on tortoises of southern province, zambia.reptiles from southern province, zambia were captured and inspected for ticks. seven of 18 tortoises (geochelone pardalis) were infested by small numbers of adults and nymphs of amblyomma marmoreum. under such circumstances, the tick had little apparent effect on the host. none of the 13 specimens representing four species of snakes examined were infested with ticks.19892810567
[ticks of the family ixodidae in guinea and the isolation of arboviruses from them. ii. results of virologic and serologic research].55697 ixodidae ticks of 35 species, belonging to 7 genera, were collected in guinea in 1981-1983. virological study of 29410 ticks was performed by intracerebral infection of newborn white mice. 49 viral strains were isolated. authors identified 38 strains of the 8 following arboviruses: dugbe, bhanja, cgl-congo (ecologically connected with ticks), blue tongue virus of sheep and abadine (association with ticks was found for the first time), kindia and forekarya (the new viruses). serological scr ...19892811754
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 ...19892815542
pheromones and other semiochemicals of the contrast to the exceptional diversity of semiochemical-regulated behavior in the insects, chemical communication in the acari is restricted to a few limited roles. these include clustering, mate-finding processes, host- and food-finding processes, and dispersal. no evidence of pheromones regulating oviposition, necrophoric behavior, recognition of hive mates, or many other processes found in numerous insect groups has been reported in the acari. perhaps the most noteworthy feature of acarine ...19852857547
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 ...19892911745
effect of age on cholinesterase activity and protein of unfed larval ticks.the cholinesterase (ache) activity and total protein in homogenates of unfed larvae of amblyomma americanum (l.), a. cajennense (fabricius), a. maculatum koch, anocentor nitens neumann, and boophilus microplus (canestrini) were determined weekly in ticks 1-6 wk of age. there was a considerable variation in total protein, ache, and the ratio of ache to protein as the ticks aged. however, ache activities were constant or increased with age and total protein levels were constant or decreased. no di ...19892918444
comparison of the isozyme phenotypes of the morphologically similar ticks amblyomma cajennense and a. imitator (acari: ixodidae) from south texas.a survey of amblyomma koch tick populations in southern texas revealed that a. imitator kohls was restricted to the two most southern counties, but that a. cajennense (fabricius) ranged at least as far north as kingsville, tex. females of the two species could be distinguished by the presence of chitinous tubercles on the festoons of a. cajennense and the presence of projections over both sides of the apron of the genital aperture in a. imitator. males were distinguished by size, ornamentation, ...19892926774
morphogenetic diapause in amblyomma variegatum (acari: ixodidae).in southern africa, amblyomma variegatum fabricius is characterized by a strict seasonal activity. experiments were carried out to determine whether a diapause mechanism regulates this seasonality. engorged a.variegatum females were exposed to controlled laboratory conditions or natural field conditions at different times of the year. females exposed in a natural environment in september-october (short day) had significantly longer pre-oviposition periods than females exposed from november to ma ...19882980187
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 ...19863014417
prevalence of piroplasmosis in equines in the colombian province of cordoba.eighty-two equine sera from 13 farms in northern colombia were examined for antibodies to babesia caballi and b. equi using the complement fixation (cf) and the indirect fluorescent antibody (ifa) test. seroreactors to both piroplasms were present on all farms. the ifa test indicated a prevalence of 90% for b. caballi and 94% for b. equi. the cf test detected antibodies to b. caballi in 41% and to b. equi in 65% of the animals. the prevalence of seroreactors in different age groups revealed a si ...19883041656
epidemiology of theileriosis in calves in an endemic area of kenya.thirty-one calves born into five maasai zebu cattle herds over a period of 1 month in the trans-mara division of kenya, endemic for theileriosis, were recruited for an intensive study of theileriosis. no calves up to 6 months of age died but all developed theileria infections as judged by slide examination and serology. parasitosis by t. mutans schizonts in lymph node smears was usually higher than that of t. parva. the t. mutans schizonts usually occurred at an earlier age but persisted at a pa ...19863085323
geographic distribution of bhanja virus.a review on the geographic distribution, vectors and hosts of bhanja virus (bunyaviridae) is based on reports about: isolations of the virus; antibody surveys. bhanja virus has been isolated in 15 countries of asia, africa and europe, and antibodies against it have been detected in 15 additional countries. vector range includes ticks of the family ixodidae (subfam. amblyomminae; not subfam. ixodinae): 13 species of 6 genera (haemaphysalis, dermacentor, hyalomma, amblyomma, rhipicephalus and boop ...19873108117
failure to detect infection in fallow deer (cervus dama) exposed to theileria cervi from white-tailed deer.a frozen stabilate was produced from theileria cervi sporozoites in salivary glands of adult amblyomma americanum. the stabilate was inoculated into three fallow deer (cervus dama) and two white-tailed deer (odocoileus virginianus). following inoculation, the white-tailed deer developed parasitemias as determined by blood smear examination at 11 and 13 days postexposure. repeat examination of blood from the three fallow deer for 30 days postexposure failed to reveal observable piro-plasms. these ...19873119873
the ultrastructure of sporogony in theileria cervi (bettencourt et al., 1907) in salivary glands of female amblyomma americanum (l.) ticks.the process of sporogony of theileria cervi in salivary glands of unfed and feeding amblyomma americanum females that were infected as nymphs was studied by light and electron microscopy (sem and tem). sporogony was observed only in granular acini type iii and in cells classified as complex granular. infected acini in salivary glands of both unfed and feeding ticks were enlarged. some stages of parasite development were evident with light microscopy and sem, but the specific events of sporogony ...19873125313
field sampling of unfed adults of amblyomma hebraeum 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, ...19873135161
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.19883137010
ticks parasitizing humans in a lyme disease endemic area of southern new york state.a total of 126 tick specimens were submitted by tick bite victims to the westchester county department of health, white plains, new york, and to the new york medical college, medical entomology laboratory, armonk, new york, during 1985. these included 96 (76.2%) ixodes dammini, 26 (20.6%) dermacentor variabilis, and two (1.6%) amblyomma americanum. i. dammini parasitism was reported during all months of the year except december and february and involved all life stages. only d. variabilis adults ...19883189288
ability to ixodes scapularis, dermacentor variabilis, and amblyomma americanum (acari: ixodidae) to acquire, maintain, and transmit lyme disease spirochetes (borrelia burgdorferi). 19883193425
susceptibility of amblyomma americanum to natural and experimental infections with theileria hundred fifty amblyomma americanum were examined between march and september 1986 from cookson hills wildlife refuge in eastern oklahoma (usa). of these ticks, 11% (17 of 150) were infected with theileria cervi. field-collected nymphal ticks had an 8% (3 of 37) prevalence of infection averaging 1.0 infected acini/nymph. female ticks had a 16% prevalence of infection averaging 1.6 infected acini/female; t. cervi was not observed in salivary glands of field-collected male ticks. when laborator ...19883193564
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.19883194113
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 ...19883194114
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 ...19883194119
feeding performance of amblyomma variegatum (acarina: ixodidae) fed repeatedly on rabbits.rabbits infested with different stages of amblyomma variegatum fabricius, 1794 became resistant to subsequent infestations by the same tick. resistance was manifested by a reduction of 73.6% in the mean engorged weight of female ticks by the 3rd infestation. by the 5th infestation, only 70% of the nymphs engorged and their mean engorged weight was 57.7% of that of nymphs fed on tick-naive control rabbits. in the case of larvae, there was a 22.8% reduction in their mean engorged weight by the 6th ...19883197579
ability of adults of amblyomma hebraeum (acarina: ixodidae) to feed repeatedly on sheep and 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 ...19883201710
medium-sized mammal hosts of amblyomma americanum and dermacentor variabilis (acari: ixodidae) at land between the lakes, tennessee, and effects of integrated tick management on host infestations. 19883204625
effects of photoperiod on nymphal diapause in amblyomma americanum (acari: ixodidae). 19883204627
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.19883210221
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.19883217097
remote recognition of amblyomma variegatum habitats in guadeloupe using landsat-tm imagery. 19883232619
[effect of natural infestation by amblyomma variegatum ticks on the growth of creole cattle and goats]. 19883253862
characterization of tick antigens inducing host immune resistance. ii. description of rabbit-acquired immunity to amblyomma americanum ticks and identification of potential tick antigens by western blot analysis.feeding by adult amblyomma americanum ticks induced a level of immunity in rabbits to subsequent tick feeding that resulted in a significant decrease in tick feeding success and fecundity. histological analysis of tick feeding sites in hosts expressing resistance revealed a predominant eosinophil response, with weak basophil and neutrophil infiltrates. while the basophil was never the dominant granulocyte at the tick feeding sites in resistant hosts, this cell exhibited the greatest increase in ...19883291384
role of small mammals in population dynamics and dissemination of amblyomma americanum and dermacentor variabilis (acari: ixodidae) at land between the lakes, tennessee. 19873295243
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 ...19873295646
heartwater. the development and life cycle of cowdria ruminantium in the vertebrate host, ticks and cultured endothelial cells.various aspects of the development and life cycle of cowdria ruminantium are discussed. c. ruminantium is transmitted transstadially by certain amblyomma species. apparently organisms initially develop in the gut epithelial cells of ticks and subsequent stages of c. ruminantium invade and develop in the salivary gland acini cells of the vector. stages at which transmission to the final host are attained appear to be coordinated with the feeding cycle of the ticks and the vertebrate host is infec ...19873329309
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 ...19873329312
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.19873329313
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 ...19873329318
the application of the indirect fluorescent antibody test in research on heartwater.the preparation of the antigen, details of the reagents, the titration of the antispecies conjugates and the execution of the indirect fluorescent antibody test are described. the sensitivity and specificity of the test and its applicability to the detection of antibodies to cowdria ruminantium are recorded. the test is both highly specific and sensitive and can be applied to a wide range of studies on heartwater, including epidemiology, determination of the c. ruminantium infection rate of ambl ...19873329322
natural transmission of heartwater.heartwater has been transmitted experimentally by 12 amblyomma species. their importance depends on the extent of their distribution, adaptation to domestic stock and their efficacy as vectors. except for one report of transovarial transmission, transmission is transstadial. ticks may obtain the infection while feeding on reacting animals, subclinically infected hosts or perhaps on immune animals after reinfection. there is a marked increase in the infectivity of infected ticks during feeding bu ...19873329324
the tick vectors of cowdria ruminantium (ixodoidea, ixodidae, genus amblyomma) and their distribution.twelve species of amblyomma are presently known to be capable of transmitting cowdria ruminantium. of these a. variegatum is the most important and widely distributed vector in africa. it has also extended its range considerably outside this continent, eastward to the yemen arab republic and to the islands of madagascar, réunion and mauritius, and westward to the cape verde islands and to some of the west indian islands. a. hebraeum is probably the only field vector in most parts of southern afr ...19873329325
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 ...19873329326
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 ...19873329327
danger of introducing heartwater onto the american mainland: potential role of indigenous and exotic amblyomma ticks.the existence of heartwater on 3 islands of the central lesser antilles and the presence of an efficient vector originating from africa, amblyomma variegatum, on most of the islands of this region constitute a serious threat for livestock on the american mainland. the disease can be introduced there either by infected animals or infected ticks. the most likely way is probably the transportation of domestic animals which are heavily infested by ticks. due to the low rate of infection of ticks in ...19873329328
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.19873329330
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 ...19873329335
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