[asymptomatic carrier state in creole goats and cattle after recovery from cowdria infection in guadeloupe].creole goats and cattle in guadeloupe can be carriers of cowdriosis (heartwater: cowdria ruminantium) after recovery for a period as long as 11 months in goats and 2 months in cattle. the carrier status was demonstrated by feeding amblyomma variegatum nymphs on recovered animals and the resulting adult ticks on susceptible goats. cowdria ruminantium was not detected permanently during the carrier status.19921301623
laboratory and field observations on anti-tick properties of the plant gynandropsis gynandra (l.) brig.a shrubby plant, abundant in east kenya, gynandropsis gynandra (l.) brig., was shown to exhibit repellent and acaricidal properties to larvae, nymphs and adult rhipicephalus appendiculatus and amblyomma variegatum ticks. all stages of ticks avoided the leaves of the plant and a high percentage of the ticks which were continuously exposed to its leaves died; surviving ticks were weak and inactive but regained activity when exposed to fresh air. the effectiveness of the plant's leaves as a repelle ...19921615623
comparative study of tick burdens in gudali and wakwa cattle under natural infestation in the subhumid highlands of wakwa, cameroon. preliminary observations.the relative resistance to different cattle ticks of gudali and wakwa cattle with different levels of brahman breeding, grazed on natural pastures in the subhumid tropics of wakwa, cameroon, was assessed using pasture tick infestations. the basic design consisted of 5 young bulls of each breed from different sire herds. tick populations were observed in gudali and wakwa bulls over a period of four weeks when the climate was thought to be highly favourable for the free-living stages of ticks. cou ...19921339999
perception of breath components by the tropical bont tick, amblyomma variegatum fabricius (ixodidae). i. co2-excited and co2-inhibited receptors.wall-pore olfactory sensilla located in the capsule of haller's organ on the tarsus of amblyomma variegatum ticks bear cells responding to vertebrate breath: one of these sensilla contains a co2-excited receptor and a second sensillum has a co2-inhibited receptor. each of these antagonistic co2-receptors, which display typical phasic-tonic responses, monitors a different co2-concentration range. the co2-inhibited receptor is very sensitive to small concentration changes between 0 and ca. 0.2%, b ...19921331433
[attempt to attract amblyomma variegatum (acarina:ixodina) on cattle previously treated with aggregation-fixation pheromones and a pyrethrinoid acaricide].the application of synthetic pheromonal aggregation-attachment compounds or male tick extracts on certain sites of the body of bull calves reared on infested pastures did not induce any attraction of free adults on these sites. previously attached males were more attractive than synthetic pheromones or natural extracts. very small amounts of flumethrin poured directly on testicles or on the dewalp induced a large decrease in the infestation of these sites.19921298024
influence of exposure period and management methods on the effectiveness of chickens as predators of ticks infesting cattle.experiments undertaken on rusinga island, kenya, indicated that rhipicephalus appendiculatus (neumann) was the predominant tick consumed on tick-infested cattle by chickens, followed by amblyomma variegatum (fabricius), boophilus decoloratus (koch) and rhipicephalus evertsi evertsi (neumann). the number of ticks consumed by chickens released with cattle in a 3 h release period was not significantly different from ticks consumed in a 4 h release period. in a free management system, chickens 1-3 m ...19921413461
perception of breath components by the tropical bont tick, amblyomma variegatum fabricius (ixodidae). ii. sulfide-receptors.wall-pore sensilla in the capsule of haller's organ on foreleg tarsi of the tick, amblyomma variegatum, show multicellular responses upon stimulation with human and bovine breath. filtering breath through charcoal removes the stimulant for some of these receptors. analysis by gas chromatography coupled with olfactory sensillum electrophysiological recordings indicates that an ethanol extract of the breath components trapped on charcoal contains a major stimulant eluting at the same retention tim ...19921432848
studies on theileriidae (sporozoa) in tanzania. i. tick transmission of haematoxenus veliferus.haematoxenus veliferus was experimentally transmitted in cattle on two occasions by the tick amblyomma variegatum; transmission was transstadial, from nymph to adult. theileria mutans and cowdria ruminatium were transmitted at the same time. h. veliferus infected at least 15% of red cells in a splenectomized steer and 10% in a normal steer. one experiment on transstadial transmission from larva to nymph was unsuccessful.19761258136
saliva-activated transmission (sat) of thogoto virus: dynamics of sat factor activity in the salivary glands of rhipicephalus appendiculatus, amblyomma variegatum, and boophilus microplus ticks.thogoto (tho) virus is transmitted from infected to uninfected ticks when co-feeding on uninfected guinea-pigs, even though the guinea-pigs do not develop a detectable viraemia. this form of non-viraemic transmission is potentiated by a factor(s) secreted by the saliva of ticks and hence has been termed saliva-activated transmission (sat). the synthesis of the sat factor by the salivary glands of three ixodid tick species was determined by placing uninfected nymphal ticks on guinea-pigs that wer ...19921326431
[isolation of thogoto virus from amblyomma and boophilus ticks in central africa].a survey has been carried out in the cameroons and the central african republic about the role of the ticks in the ecology of arboviruses in central africa. attempts for virus isolation were made for 12,678 amblyomma variegatum, 3,276 boophilus decoloratus and 1,769 boophilus annulatus, by inoculation into suckling mice. from 968 pools which were inoculated, 20 yielded isolates which were identified to thogoto virus. considering previously published results concerning tick-borne virus isolations ...19761037382
tick paralysis in a sheep caused by nymphs of amblyomma variegatum. a preliminary report. 1976988681
studies on theileriidae (sporozoa) in tanzania. iii. experiments on the transmission of theileria mutans by rhipicephalus appendiculatus and amblyomma variegatum (acarina, ixodidae).the parasite considered to be theileria mutans in east africa could not be transmitted transstadially by rhipicephalus appendiculatus (seven attempts); it was transmitted by amblyomma variegatum in 6 out of 7 experiments. the possibility that the original south african t. mutans, transmissible by r. appendiculatus, and the parasite called t. mutans in east africa, are different species, has to be considered.1976824772
use of high-performance liquid chromatography to separate very small quantities of radio-labelled metabolites from biological order to study the absorption, metabolism and tissue distribution of chemicals in cattle ticks amblyomma variegatum, a method of separating and recovering metabolites in picogram quantities was required. a high-performance liquid chromatographic system has been investigated for this purpose, using tritium-labelled amitraz and some potential metabolites. separation was carried out on nucleosil 5 mum no2 bonded phase. interchangeable pre-columns were used to extend the range of compounds which ...1977914943
egg output in the weights and states of engorgement of amblyomma variegatum (fabr.) and boophilus annulatus (say): (ixodoidea: ixodidae).the relationship between egg output and the weights and states of engorgement of two species of ixodid ticks amblyomma variegtum (fabr.) and boophilus annulatus (say) was studied, using over 3,000 female ticks of different sizes. based on the average weights and numbers of eggs produced, guide indices are provided for the predictability of the oviposition potential in females of different weights. linear correlation was noted between weights of the ticks and the weights and numbers of eggs they ...1977881144
tick-borne diseases of domestic animals in northern nigeria. ii. research summary, 1966 to 1976.during the first 10 years of its existence, the department of parasitology and entomology of the faculty of veterinary medicine, ahmadu bello university in zaria, nigeria, confirmed or described for the first time the occurrence of 25 different tick-borne parasites of domestic animals in the northern part of the country. most of these organisms occur as inapparent infections but may serve as complicating factors in any adverse host condition. the transmission of babesia bigemina by boophilus dec ...1977339447
[isolation of the yellow fever virus from an egg-cluster and the larvae of the tick amblyomma variegatum].the yellow fever virus is isolated in natura from eggs of a tick amblyomma variegatum. it is then isolated from larvae issued from the same egg-cluster and also from blood of a monkey bitten by larvae of the same origin. it is reported that the same virus has been previously obtained from adults of the same species of tick. an acarine appears for the first time as a sylvatic vector and reservoir (at least temporary) of yellow fever.1979117946
theileria mutans in nigeria.two strains of bovine theileria from northern nigeria were shown to be identical to theileria mutans in the indirect immunofluorescent antibody test. one of the strains was transmitted by the tick amblyomma variegatum; large macroschizonts, typical for t mutans, could be demonstrated in infected cattle. it is concluded from these experiments and from the literature that there is reliable evidence so far for the occurrence in nigeria of only two bovine tehileria species, t mutans and t velifera.1979117536
on the use of the scrotum for feeding larval ixodid ticks on hosts.the efficacy of feeding larval stages of amblyomma variegatum, hyalomma rufipes and boophilus decoloratus on the ears and scrotum of sheep is compared. the effect of age of larvae on the number that engorged on the animal was also investigated. a significantly greater number of larvae fed on scrotum than on ears. the greatest number of larvae engorged when they were fed on the scrotum or ear within 1-4 days of hatching. the older the larvae, the less the number that fed. the economic advantages ...1977860573
studies on theileriidae (sporozoa) in tanzania. vii. additional note on the transmission of theileria parva.rhipicephalus evertsi successfully transmitted fatal east coast fever (theileria parva infection) in one experiment. a second one gave negative results, as did an attempted transmission of t. parva by amblyomma variegatum.1977407682
the role of amblyomma variegatum in the transmission of heartwater with special reference to guadeloupe.heartwater has been diagnosed in guadeloupe, marie-galante, and antigua; it induces important losses among goats and european or cross-bred cattle when local zebu creole are highly resistant to infection. amblyomma variegatum is the vector of the disease in the caribbean. the tick strain of martinique, occurring in that island that has apparently been disease-free since 1948, has not lost its ability to experimentally transmit the disease. in guadeloupe 97% of nymphs and nearly 100% of adults fe ...19921626882
studies on theileriidae (sporozoa) in tanzania. v. preliminary experiments on a new method for infecting ticks with theileria parva and theileria mutans.bovine blood with a high parasitaemia of theileria mutans was injected through the cuticle into fully engorged nymphs of amblyomma variegatum which had recently detached from a rabbit. after moulting, they transmitted this parasite to a susceptible calf. rhipicephalus appendiculatus transmitted theileria parva in the same way, but results were negative with a. variegatum and t. parva. this method of infecting ticks appears promising for the isolation of theileria strains from the field, and migh ...19761006800
detection of an arbovirus in an invertebrate and a vertebrate host using the polymerase chain reaction.the ability of the polymerase chain reaction (pcr) to diagnose an arboviral infection in an arthropod vector or a mammalian host was examined. dugbe (dug) viral rna was detected in rna extracts from infected tissue samples by reverse transcription and enzymatic amplification of the resulting cdna using taq dna polymerase, followed by characterisation of the amplified product by agarose gel electrophoresis or dot-blot hybridisation. viral rna was detected in the organs and haemolymph of infected ...19901707893
development of theileria mutants (aitong) in the tick amblyomma variegatum compared to that of t. parva (muguga) in rhipicephalus appendiculatus.a comparison was made between the development of theileria mutans (aitong) in adult amblyomma variegatum ticks and the development of t. parva (muguga) in adult rhipicephalus appendiculatus ticks. both batches of ticks dropped as engorged nymphs from cattle whose intraerythrocytic parasitemias were approximately 40%, and it was thus possible to make a direct comparison of the infection rates produced in their tick hosts in this experiment by the 2 species of theileria. ticks of the 2 batches wer ...1975809568
acaricide susceptibility of amblyomma variegatum (acari:ixodidae) from puerto rico and guadeloupe.base-line data on acaricide susceptibility of larvae and of larvae and nymphs of the tropical bont tick, amblyomma variegatum (fabricius), from puerto rico and guadeloupe were collected on 14 and six compounds, respectively. nymphs 7-8 weeks old from puerto rico and guadeloupe, and larvae 3-4 weeks old from guadeloupe, were exposed for 24 or 48 h to residues of acetone dilutions of technical-grade or commercial formulations of acaricides on disposable glass pipettes. effectiveness of the acarici ...19911773678
a cloned dna probe identifies cowdria ruminantium in amblyomma variegatum ticks.heartwater, caused by cowdria ruminantium and transmitted by ticks of the genus amblyomma, is a constraint to ruminant animal production in sub-saharan africa. this rickettsial disease could spread from endemically infected areas of sub-saharan africa and certain caribbean islands to other countries, including the united states, in which amblyomma ticks exist. to detect c. ruminantium in tick vectors and animals, we made dna probes from c. ruminantium dna isolated from endothelial cell cultures. ...19911774264
predators of the tick amblyomma variegatum (acari: ixodidae) in guadeloupe, french west indies.some vertebrate species in guadeloupe are predators of free or parasitic stages of amblyomma variegatum (fabricius). among birds, 1.9% of the 421 identified animals found in the stomachs of grackles (quiscalus lugubris), 1.6% of the 364 animals found in the stomachs of free-ranging chickens, and 0.3% of the 4642 animals found in the stomach of cattle egrets (bubulcus ibis) were a. variegatum ticks. the most efficient predator of ticks was the tropical fire ant, solenopsis geminata, which was obs ...19911773677
genetic basis for organochlorine resistance in amblyomma variegatum and information on the susceptibility on a. lepidum to organochlorine acaricides. 1979544643
comparison of known and suspected pheromonal constituents in males of african ticks, amblyomma hebraeum koch and amblyomma variegatum (fabricius).three low molecular weight compounds were found in hexane:diethyl ether extracts of fed males of the african ticks, amblyomma variegatum (tropical bont tick) and a. hebraeum (bont tick), namely, o-nitrophenol, methyl salicylate and 2,6-dichlorophenol. these same compounds were also fond in a rinse of fed a. variegatum males, but were absent or present in only trace amounts in a rinse of fed a. hebraeum males, o-nitrophenol and methyl salicylate were present in much higher concentrations (i.e., a ...19911786745
parasite burdens and host susceptibility of zebu and n'dama cattle in village herds in gambia.helminth and tick burdens of n'dama cattle kept in village herds were compared with parasite burdens in zebu cattle introduced into the same herds. the animals were monitored regularly for tick and helminth burdens, and blood samples were examined for differential white cell counts. the zebu were found to have significantly higher numbers of endo- and ectoparasites. the n'dama had significantly higher levels of circulating eosinophils than the zebu during peak parasite burdens. no difference in ...19911788936
the occurrence of streptothricosis and its association with amblyomma variegatum ticks in st. lucia.cattle, horses, sheep and goats in all areas of st. lucia were examined to ascertain the prevalence and distribution of streptothricosis on the island and to investigate its association with the occurrence of amblyomma variegatum ticks. although the disease was found to occur throughout st. lucia it was more prevalent and generally of a more severe form in areas where a. variegatum ticks are present. a tick control programme in the north of the island appeared to have resulted in a dramatic redu ...19911789020
[the tick amblyomma variegatum (ixodidae), apparently resistant to arsenic, in madagascar]. 19751230882
[seasonal dynamics of tick infestations in cattle (ixodoidea) in cattle sold in the area of yaoundé, cameroon].among the tick species identified in cameroon, eight were found in cattle in yaoundé: amblyomma variegatum, boophilus annulatus, b. decoloratus, haemaphysalis aciculifer, hyalomma nitidum, rhipicephalus longus, rh. lunulatus, rh. sulcatus. three species, hm. aciculifer, h. nitidum and rh. lunulatus, were identified for the first time in yaoundé. rhipicephalus and hyalomma were abundant during the rainy season. boophilus was abundant throughout the year, with a maximum concentration at the end of ...19911824137
re-assessment of tick control after immunization against east coast fever in the eastern province of zambia.east coast fever, caused by the protozoon theileria parva and transmitted by the ixodid tick rhipicephalus appendiculatus is one of the most important cattle diseases in east and central africa, responsible for considerable direct losses and necessitating expensive control measures. traditionally, the disease was controlled by means of intensive tick control. the belgian animal disease control project was requested to study the disease epizootiology and vector ecology in order to formulate and i ...19911793284
dissemination, replication, and trans-stadial persistence of dugbe virus (nairovirus, bunyaviridae) in the tick vector amblyomma variegatum.the dissemination and replication of dugbe (dug) virus and its tissue tropisms in the tick vector amblyomma variegatum were examined by immunohistochemical analysis using specific antibody, in situ hybridization with a viral-complementary riboprobe, and infectivity assays of dissected tissues. dugbe virus was localized in both unfed and feeding adults inoculated as nymphs or orally infected by capillary feeding, and in nymphs infected by capillary feeding. in non-feeding ticks, the main sites of ...19911867347
crimean-congo haemorrhagic fever virus replication in adult hyalomma truncatum and amblyomma variegatum ticks.the kinetics of the replication of the crimean-congo haemorrhagic fever virus (cchfv) was studied in intra-anally inoculated adult hyalomma truncatum and amblyomma variegatum ticks. the virus was re-isolated by suckling mouse inoculation and revealed by antigen capture with ground ticks and indirect immunofluorescence of haemolymph. the virus was detected in ticks in the first hours post-inoculation (p.i.) and its replication was observed from 36 h p.i. onwards. virus titre reached a maximum wit ...19911803413
[transovarian passage of dugbe virus in the tick amblyomma variegatum (fabricius)]. 1978719844
comparative studies on the vector capacity of the different stages of amblyomma variegatum fabricius and hyalomma rufipes koch for congo virus, after intracoelomic inoculation.groups of nymphs and adults of hyalomma rufipes and larvae, nymphs and adults of amblyomma variegatum were infected by intracoelomic inoculation with congo virus at concentrations of 10(3.5)ld50 (group a), 10(1.5)ld50 (group b) and 10(0.5)ld50 (group c). the infection rates for the different groups were: groups a, 92-100% for all stages of ticks, except for adult h. rufipes which had 87%; group b, 56.8, 68.1 and 50.7% for larvae, nymphs and adults of a. variegatum, respectively, and 96.3 and 84. ...19911907050
on the life cycle of theileria velifera (uilenberg, 1964) in the gut and the haemolymph of the tick vector amblyomma variegatum (fabriciu, 1794).the development of theileria velifera in the gut and the haemolymph of the tick vector amblyomma variegatum is described. between days three and eight after repletion various sexual stages are present in the gut of the nymphs. zygotes were detected in the gut on day 14, while undifferentiated kinetes first appeared on day 15. in the haemolymph, differentiated kinetes were observed from day 16 after repletion onwards. zygotes and kinetes were also found after the moult, in the adult tick, for a p ...1979120627
studies on ticks of veterinary importance in nigeria: intrinsic factors influencing oviposition and egg-hatch of amblyomma variegatum under natural conditions.during the peak of rains of 1983, 1984 and 1985 in the forest zone of nigeria, female amblyomma variegatum engorged to various weights were subjected to different experiments for the purpose of observing the intrinsic factors which influence oviposition and egg-hatch under natural conditions. two types of oviposition patterns were observed. new terms were introduced to quantify the relationships between the daily weight loss and daily number of eggs oviposited by a tick. these terms are "actual ...19911916533
the effect of amblyomma variegatum on liveweight gain of cattle in zambia.the effect of the tick amblyomma variegatum fabricius on liveweight gain (lwg) on yearling cattle over 16 weeks was evaluated under quasi-natural conditions. early in the exposure period when animals may have been in a state of suppressed metabolism, the effect of tick feeding on lwg was negligible. overall, however, the difference in lwg between tick-free and tick-infested groups of cattle was 4.95 kg after 16 weeks. this difference between the groups was used to estimate a lower lwg of 48-63 g ...19902132999
a comparative study of the infection thresholds of thogoto virus in rhipicephalus appendiculatus and amblyomma variegatum.infection thresholds of thogoto virus in 2 ixodid tick species, rhipicephalus appendiculatus and amblyomma variegatum, were compared. thogoto virus has been isolated from naturally infected r. appendiculatus and a. variegatum in central africa, where both commonly parasitize the same hosts. no significant difference was found between the infection thresholds of thogoto virus in the 2 species. the percentage of nymphs of both species infected by feeding on viremic hamsters was directly correlated ...19902166447
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
theileria mutans the infectivity for cattle of parasites derived from prefed amblyomma variegatum nymphs.a steer was infected with theileria mutans (aitong) by application of infected amblyomma variegatum nymphs. uninfected a. variegatum larvae were applied to this steer when piroplasms developed. the resultant (and infected) a. variegatum nymphs were applied to the ears of rabbits. equal numbers of ticks were removed daily from rabbits and ground in eagles minimal essential medium. the infectivity of the supernatant fluid was tested in cattle. the produced supernatant fluids were infective between ...1977414391
[ticks and hemoparasitic diseases in cattle in senegal. iv. the southern sudan area].the authors report on the results of an investigation on ticks and hemoparasitoses of cattle, sheep and goats in the south sudanian area of senegal. systematic routine dipping against ticks of cattle, 40 sheep and 40 goats was set during 15 months, with a view to determine the population dynamics together with an acurate localization of the different species concerned. the following parasites were collected from these ruminants: amblyomma variegatum, boophilus geigyi, hyalomma truncatum, h. m. r ...19902218038
tick infestations on zebu cattle in western kenya: individual host variation.monthly collections were made of all ticks from 25 mature east african zebu cattle and 5 yearlings for 13 mo on rusinga island, lake victoria, kenya, from september 1986 to september 1987. the most common species were rhipicephalus appendiculatus neumann and amblyomma variegatum f.; boophilus decoloratus koch and rhipicephalus evertsi evertsi neumann also were present in fewer numbers. cattle were ranked according to their degree of resistance to each of the four species and to each stage in the ...19912033602
[prevention of cowdriosis and cases of sheep diseases in the niayes region of senegal].sheep originating from an heartwater-free area were immunized by the infection and treatment method, using long-acting oxytetracycline. the animals were then exposed, together with control sheep to natural infection in an enzootic area. tick counts were made to monitor the infestation and establish a correlation between infestation by certain tick species, in particular amblyomma variegatum, and the occurrence of cowdriosis. in some cases of death associated with ehrlichiosis and anaplasmosis in ...19902218032
amblyomma variegatum and associated diseases in the caribbean: strategies for control and eradication in guadeloupe.amblyomma variegatum, introduced into guadelopue 150 years ago, has recently spread in the lesser antilles and threatens north america. two important diseases are associated with the tick: heartwater and dermatophilosis. heartwater occurs in guadeloupe, marie-galante and antigua; acute dermatophilosis exists almost everywhere the tick is present. both are very pathogenic for upgraded or newly-infested cattle. after 15 years of a. variegatum control in guadeloupe, a balance is established between ...19902284130
[ticks of the ixodidae family as reservoir of arboviruses in the republic of guinea. ii. arboviruses].from 1978 to 1985, 96,167 ixodidae family were collected, from which 79 strains of the following arboviruses were isolated, i.e. 4 bhanja strains, 9 chf-congo, 20 dugbe, 24 jos (viruses ecologically related to ticks), 10 abadina, 7 bluetongue, 1 bunyamwera, 1 chikungunya, (related to ticks for the first time), 1 kindia and 2 forecariah (new viruses). the main sources for arbovirus isolation were ticks of the amblyomma variegatum genus (78.5%) followed by ticks of the boophilus (12.6%), rhipiceph ...19902263738
non-viraemic transmission of thogoto virus: vector efficiency of rhipicephalus appendiculatus and amblyomma variegatum.previous studies have demonstrated that thogoto virus is transmitted from infected to uninfected ticks when co-feeding on uninfected guinea-pigs, even though the guinea-pigs do not develop a detectable viraemia. furthermore, tick to tick transmission is potentiated by factors associated with the salivary glands of ticks (saliva activated transmission). the vector efficiency of 2 ixodid tick species, rhipicephalus appendiculatus and amblyomma variegatum, for thogoto virus was assessed using this ...19902096521
[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
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
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
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
the impact of natural infestations of ticks in zambia on the productivity of cattle and implications for tick control strategies in central africa.studies were carried out in zambia using a farming systems approach to quantify the effects of tick control on traditionally managed sanga cattle. in the first trial to investigate the effect of tick control, significant improvements in liveweight gain (lwg) occurred only in periods of medium to high challenge with adult amblyomma variegatum. however, during the first 18 months of the study when animals were young, the acaricide used caused a suppression in weight gains. a supplementary experime ...19902126618
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
distribution and incidence of ectoparasites on small mammals in a rainforest belt of southern nigeria.a total of 174 small mammalian hosts were trapped in ekpoma, bendel state, nigeria from october, 1986 to september, 1987 and examined for ectoparasites. 108 infested hosts had 10 species of ectoparasites comprising three species of mites (laelaps (echinolaelaps) muricola, laelaps (e.) gigantea and laelaps (e.) echidninus); two species of ticks (amblyomma variegatum and ixodes sp.); two species of fleas (xenopsylla cheopis and x. braziliensis); and on especies each of sucking lice (polyplax spinu ...19911928798
tick (acari: ixodidae) infestations on zebu cattle in western kenya: seasonal dynamics of four species of ticks on traditionally managed cattle.a study was conducted on the population dynamics of four tick species infesting livestock on rusinga island. infestations of rhipicephalus appendiculatus neumann, rhipicephalus evertsi evertsi neumann, amblyomma variegatum (f.)., and boophilus decoloratus (koch) were monitored on east african shorthorn zebu cattle at monthly intervals for 2 yr. these cattle were of unimproved stock under traditional husbandry without any tick control practices. most ticks were on cattle between september and mar ...19911941930
[sites of fixation of amblyomma variegatum ticks on their hosts in guadeloupe (french west indies)].the examination of 458 domestic and wild hosts of the tick a. variegatum allowed to collect 8,581 larvae, 646 nymphs, 685 adults in 9 different animal species and to determine their preferential attachment sites. in another survey on 15 goats and 5 cattle, 12,345 larvae, 2,111 nymphs and 4,625 adults were counted on the anatomic sites. immature ticks feed preferentially on the head, neck and limbs of birds, the limbs of mongoose and the limbs and ears of dogs, goats and cattle. adults feed only ...19911843828
predation on livestock ticks by chickens.chickens were shown to be natural predators of ticks. rhipicephalus appendiculatus were recovered in large numbers from the crops and gizzards of chickens which had scavenged for 30 min-1 h among tick-infested cattle. other ticks recovered were amblyomma variegatum and boophilus decoloratus. the numbers of ticks recovered ranged from 3 to 331, with an average of 81 per chicken. cattle facilitated the predation of ticks by certain behavioural actions. chickens also picked up both engorged and une ...19911858289
histopathology of attachment sites of amblyomma variegatum and rhipicephalus appendiculatus on zebu cattle of varying resistance to ticks.mature, unimproved east african zebu cattle (bos indicus) naturally exposed to ticks from birth were ranked for resistance to ticks by repeated whole-body counts of infesting ticks. four cattle of high resistance, four of low resistance and two of intermediate resistance were artificially infested with nymphs of amblyomma variegatum and rhipicephalus appendiculatus. two friesian cattle (bos taurus) with less exposure to ticks were similarly infested. biopsies of tick attachment sites were examin ...19911858290
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
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
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
dugbe virus replication in nymph and adult amblyomma variegatum. 19892772415
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
[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
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
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
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
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
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
[effect of natural infestation by amblyomma variegatum ticks on the growth of creole cattle and goats]. 19883253862
remote recognition of amblyomma variegatum habitats in guadeloupe using landsat-tm imagery. 19883232619
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
[spreading of the tick amblyomma variegatum in the west indies: how can this serious menace be explained and what should be done?].the author presents a brief history of the introduction and extension of the african tick amblyomma variegatum in the caribbean. the tick is particularly dangerous for the livestock industry because of its role as a vector of heartwater and its association with severe dermatophilosis. it is already distributed in the lesser antilles from puerto rico to barbados and st. vincent. the chronology of its sudden unexplained expansion since the 1960s corresponds well with the multiplication of the catt ...19902103050
the reservoir status of goats recovered from heartwater.experiments were conducted with creole goats and amblyomma variegatum ticks in guadeloupe to investigate whether it is possible to transmit cowdria ruminantium to susceptible hosts with nymphs fed in the larval stage on recovered goats. of 88 batches of larvae fed after the return of the goats' temperature to normal, or after challenge or immunosuppression, only the 9 batches of larvae fed during the febrile reaction, 2 batches applied 2 and 3 days respectively after recovery, and a single batch ...19873448574
cowdria ruminantium: stability and preservation of the organism.blood collected in either sodium heparin or disodium edetate vacutainers from febrile goats infected with 4 isolates of cowdria ruminantium and cryopreserved with 10% dimethyl sulphoxide at -70 degrees c and -196 degrees c was an effective stabilate to initiate heartwater infections in goats. a homogenized pool of whole amblyomma variegatum ticks in snyder's buffer, maintained at -196 degrees c, was used to infect a goat with c. ruminantium. liver and spleen collected from swiss mice infected wi ...19873448560
epidemiology of heartwater in guadeloupe and in the present, heartwater in the caribbean is known with certainty only on guadeloupe, marie galante and antigua; the first 2 islands are widely infected. the most important factors responsible for particular aspects of heartwater in guadeloupe are: cowdria ruminantium of high virulence. a very resistant cattle population (creole), not normally clinically affected. a fairly susceptible goat population (creole) (22% goats born in endemic areas die after experimental inoculation) which, fortunately, ...19873448572
ecology and phenology of ticks in zambia: seasonal dynamics on cattle.a study of the seasonality and infestation rates of ticks was carried out in 11 cattle herds in different ecological habitats in zambia between 1980 and 1982. wherever possible supplementary data were obtained from opportunistic collections from cattle and other hosts. analysis of over 1000 tick collections from cattle indicated that infestation rates of the most important species, amblyomma variegatum and rhipicephalus appendiculatus vary in different ecological habitats: (i) in western provinc ...19863451861
the effect of immersion in water on the immature stages of the ixodid ticks-rhipicephalus appendiculatus neumann 1901 and amblyomma variegatum fabricius 1794. 19734787718
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
[trial of flumethrine for amblyomma variegatum tick control on a cattle ranch in guadeloupe]. 19873453502
[oviposition and longevity of amblyomma variegatum fabricius, 1794 (ixodoidea : ixodidae) ticks in the people's republic of the congo]. 19873453516
susceptibility of ticks to acaricides in zambia.the susceptibility of some zambian ticks to dieldrin, dioxathion, dimethoate and chlorfenvinphos was determined on two- to three-week-old larvae of amblyomma variegatum, boophilus decoloratus, b. microplus, rhipicephalus appendiculatus, r. e. evertsi and a member of the r. pravus group. some strains of b. decoloratus and r. appendiculatus were resistant to dieldrin, dioxathion and dimethoate and some r. e. evertsi were resistant to dieldrin and dioxathion. a single strain of an r. pravus group t ...19846730000
theileria orientalis occurs in central outbreak of bovine theileriosis in burundi was investigated and the occurrence of theileria orientalis in central africa was confirmed for the first time. its identity was established on morphological and serological grounds. the parasite was associated with clinical signs and further complicates the disease picture of bovine theileriosis in africa. amblyomma variegatum is suspected as being the local vector.19863517994
demonstration of colonies of cowdria ruminantium in midgut epithelial cells of amblyomma variegatum.the development of colonies of cowdria ruminantium was studied in midgut epithelial cells of adult amblyomma variegatum that had become infected by feeding as nymphs on cattle with experimentally induced heart-water disease. colonies were not observed in gut tissues obtained from nymphs during the feeding period, but were present in midgut epithelial cells of ticks obtained at 15 days after they were replete through molting to the adult stage. colonies were small (1 to 10 micron) initially, but ...19873551699
prevalence of ectoparasites of small ruminants in nsukka, nigeria.over a period of one year (january 1983 to december 1983), an investigation was mounted to determine common ectoparasitic infestation of small ruminants in selected farms in nsukka, nigeria. the species identified in goats included ctenocephalides canis, boophilius decolouratus and amblyomma variegatum lides while those recovered from parasitized sheep were ctenocephalides canis and damalinia ovis. out of a total of 148 sheep and goats examined for ectoparasites, 68 (45.95%) were infested. a fur ...19853836218
tick infestations on livestock in the yemen arab republic and their potential as vectors of livestock diseases.a survey of ticks on cattle, camels, sheep, goats and donkeys in four different geographical locations of the yemen arab republic (yar) was carried out to provide more information on the possible risk of tick-borne diseases to imported exotic cattle included in the yar's plans for livestock development. the most abundant ticks were hyalomma spp. particularly on camels. ticks found on cattle included hyalomma spp., amblyomma variegatum, boophilus annulatus and rhipicephalus spp. in general with t ...19873603710
[isolation of a new orbivirus kindia (palyam group) from ticks amblyomma variegatum in the republic of guinea].a new arbovirus named "kindia" has been isolated from ticks amblyomma variegatum in guinea (west africa), district kindia. this virus is classified into palyam group of orbiviruses, due to its physico-chemical, biological and antigenic properties.19863731365
[preliminary note on the sensitivity of amblyomma variegatum and boophilus decoloratus (acarida, ixodidae) to organophosphate acaricides in the people's republic of the congo]. 19853841963
studies on ticks of veterinary importance in nigeria. xii. oviposition and eclosion in five species of ixodid ticks in contrasting habitats.the preoviposition and oviposition periods, the eclosion periods and numbers of eggs laid by adult ticks of five species, namely amblyomma variegatum, boophilus decoloratus, b. geigyi, hyalomma rufipes and h. truncatum, maintained in a natural habitat were compared with those maintained in semi-natural and artificial habitats. within the natural habitats, "open" and "shady" sites were distinguished. maximum oviposition occurred during the peak of the rains in engorged a. variegatum and b. decolo ...19853870956
amblyomma variegatum (acari: ixodidae): population dynamics and hosts used during an eradication program in puerto rico. 19873820244
hosts and population dynamics of amblyomma variegatum (acari: ixodidae) on guadeloupe, french west indies. 19883351867
field tests of the response of female amblyomma variegatum (acari:ixodidae) to the synthetic aggregation-attachment pheromone and its components.fifty percent of an amblyomma variegatum female population were able to find upwind-positioned targets containing the synthetic aggregation-attachment pheromone of this species or the pheromone component o-nitrophenol alone. the ticks were not attracted to the other components of the pheromone: methyl-salicylate and pelargonic acid. the mean time required for the ticks to reach a target at 1 m from the starting point was 3 min and 20 s.19863451866
abnormal development of amblyomma variegatum (acarina: ixodidae). 19883351871
studies on ticks of veterinary importance in nigeria xvii. resistance of rabbits to infestation with amblyomma variegatum and boophilus decoloratus (acari: ixodidae).rabbits exposed to larvae, nymphs and adults of amblyomma variegatum acquired resistance to the infestation with adults of this tick. the degree of acquired resistance was lowest in the rabbits exposed once previously to larvae and highest in those exposed twice previously to adults. rabbits also acquired resistance after primary infestation with boophilus decoloratus; their resistance became very high during the thrice-repeated feeding. new terms are introduced for the quantification of the deg ...19846510837
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