| african swine fever virus replication in the midgut epithelium is required for infection of ornithodoros ticks. | although the malawi lil20/1 (mal) strain of african swine fever virus (asfv) was isolated from ornithodoros sp. ticks, our attempts to experimentally infect ticks by feeding them this strain failed. ten different collections of ornithodorus porcinus porcinus ticks and one collection of o. porcinus domesticus ticks were orally exposed to a high titer of mal. at 3 weeks postinoculation (p.i.), <25% of the ticks contained detectable virus, with viral titers of <4 log(10) 50% hemadsorbing doses/ml. ... | 1999 | 10482612 |
| dusky-footed wood rats (neotoma fuscipes) as reservoirs of granulocytic ehrlichiae (rickettsiales: ehrlichieae) in northern california. | dusky-footed wood rats (neotoma fuscipes) and peromyscus sp. mice (p. maniculatus and p. truei) were collected from one site in placer county, one site in santa cruz county, and two sites in sonoma county in northern california. serum or plasma samples from 260 rodents were tested for antibodies to the agent of human granulocytic ehrlichiosis. of these, samples from 25 wood rats (34% of those tested) and 10 (8%) peromyscus sp. mice were found to be seropositive, but only those from one site. pcr ... | 1999 | 10488199 |
| the current epidemiological status of bovine theileriosis in eastern zambia. | results of a longitudinal study conducted in the eastern province of zambia from 1994 to 1997 indicate that it is doubtful whether a state of endemic stability of east coast fever (ecf) can be reached in the near future. even in endemic areas, the mortality of theileria parva infections is still estimated above 50%. the main factors limiting progress towards endemic stability are high innate susceptibility of the zebu cattle, the virulence of the parasite and the climate. the unimodal rainfall p ... | 1999 | 10540309 |
| epidemiological uses of a population model for the tick rhipicephalus appendiculatus. | the spatial and temporal risk of tick-borne disease depends fundamentally on the distribution, abundance and seasonal dynamics of the vector ticks. the latter factor exerts a major quantitative influence on the transmission dynamics of tick-borne parasites. the population model for rhipicephalus appendiculatus applies throughout the range of this tick in eastern africa, and predicts all three fundamental risk factors on the basis of the local temperature and rainfall conditions. satellite imager ... | 1999 | 10540310 |
| spatial and temporal variation in rhipicephalus appendiculatus size in eastern zambia. | the size of rhipicephalus appendiculatus collected at different altitudes in the eastern province of zambia between february 1985 and may 1986 and between october 1994 and december 1996 showed distinct variation dependent on altitude and season. the ticks were smallest during the dry season and at the start of the rains, and specimens were larger as the rainy season progressed. second-generation adults where on average smaller than first-generation ticks. at higher altitudes, where a one-generat ... | 1999 | 10540311 |
| spatial and temporal distributions of parasites: can wild and domestic ungulates avoid african tick larvae? | infestation of a new host is a crucial stage in the life-cycle of parasites, and the possibility that hosts avoid infesting contact depends, in part, on the predictability of infestation risk. immature free stages of ticks (acari, ixodidae) have limited mobility and survival in the vegetation and strongly depend on host behaviours for their infestation. we studied spatial and temporal distributions of the larvae of 2 major groups of african risk species in a ranch in zimbabwe. no difference in t ... | 1999 | 10599078 |
| comparison of acetylcholinesterase genes from cattle ticks. | we describe the isolation and characterisation of two putatively new acetylcholinesterase genes from the african cattle ticks boophilus decoloratus and rhipicephalus appendiculatus. the nucleotide sequences of these genes had 93% homology to each other and 95% and 91% identity, respectively, to the acetylcholinesterase gene from an australian strain of another cattle tick, boophilus microplus. translation of the nucleotide sequences revealed putative amino acids that are essential for acetylchol ... | 1999 | 10616922 |
| parasites of domestic and wild animals in south africa. xxxvii. ixodid ticks on cattle on kikuyu grass pastures and in valley bushveld in the eastern cape province. | individual calves, exposed to infestation for 14 d on dry-land kikuyu grass pastures on the coast near alexandria, were slaughtered at approximately monthly intervals over a period of 2 years and examined for ticks. although seven species were recovered total tick burdens were for the most part low. changing the acaricide with which other cattle on the farm, but not the survey calves, were treated from an organophosphate-based compound to a synthetic pyrethroid resulted in a marked sustained red ... | 1999 | 10631707 |
| immunity reduces reservoir host competence of peromyscus leucopus for ehrlichia phagocytophila. | infection with ehrlichia phagocytophila in white-footed mice is transient and followed by a strong immune response. we investigated whether the presence of acquired immunity against e. phagocytophila precludes white-footed mice from further maintenance of this agent in nature. mice were infected with e. phagocytophila via tick bite and challenged either 12 or 16 weeks later by ixodes scapularis nymphs infected with the same agent. xenodiagnostic larvae fed upon each mouse simultaneously with cha ... | 2000 | 10678968 |
| pathological effects and reduced survival in rhipicephalus appendiculatus ticks infected with theileria parva protozoa. | pathological effects have been demonstrated in a number of arthropod species as a consequence of parasitic infection. this is usually manifest as reduced arthropod survival and/or fecundity. this paper describes the detrimental effects the protozoan parasite, theileria parva has on rhipicephalus appendiculatus ticks. r. appendiculatus ticks were dissected and sectioned at regular intervals during their nymph to adult moult after detaching from a t. parva infected calf, and assessed by light and ... | 2000 | 10726991 |
| a rapid method to select rhipicephalus appendiculatus salivary glands infected with theileria parva. | | 1984 | 6439849 |
| cutaneous responses of cattle to extracts from rhipicephalus appendiculatus larvae. | a component of an extract from rhipicephalus appendiculatus larval ticks induced an immediate hypersensitivity reaction in sensitized cattle when intra-dermally inoculated. generally, the magnitude of the cutaneous reaction depended upon the duration of exposure of the cattle to tick infestation. the skin reaction was absent in steers not previously fed on by ticks. field trials, using the extract in the narok district of kenya (masailand), showed that the skin swelling thus induced was biggest ... | 1984 | 6541396 |
| development of an indirect tams1 enzyme-linked immunosorbent assay for diagnosis of theileria annulata infection in cattle. | an enzyme-linked immunosorbent assay (elisa) was developed based on a recombinant major theileria annulata merozoite surface antigen, tams1. four different recombinant proteins derived from two different tams1 alleles, both in two different truncated forms, were tested for their performance in the elisa. furthermore, antigen concentration, various buffers, washing protocol, and the choice of anti-total-immunoglobulin g (igg), anti-igg1, or anti-igg2 as second antibody were evaluated. the perform ... | 2000 | 10799453 |
| a monomeric gtpase-negative mxa mutant with antiviral activity. | mxa is a large, interferon-induced gtpase with antiviral activity against rna viruses. it forms large oligomers, but whether oligomerization and gtpase activity are important for antiviral function is not known. the mutant protein mxa(l612k) carries a lysine-for-leucine substitution at position 612 and fails to form oligomers. here we show that monomeric mxa(l612k) lacks detectable gtpase activity but is capable of inhibiting thogoto virus in transiently transfected vero cells or in a thogoto vi ... | 2000 | 10933733 |
| earth observation, geographic information systems and plasmodium falciparum malaria in sub-saharan africa. | this review highlights the progress and current status of remote sensing (rs) and geographical information systems (gis) as currently applied to the problem of plasmodium falciparum malaria in sub-saharan africa (ssa). the burden of p. falciparum malaria in ssa is first summarized and then contrasted with the paucity of accurate and recent information on the nature and extent of the disease. this provides perspective on both the global importance of the pathogen and the potential for contributio ... | 2000 | 10997207 |
| optimization of the in vitro feeding of rhipicephalus appendiculatus nymphae for the transmission of theileria parva. | an apparatus for artificial feeding of rhipicephalus appendiculatus nymphae was modified to improve feeding performance. heparinized blood was supplied above a treated artificial membrane while the ticks attached below on its undersurface. the feeding apparatus was incubated at 37 degrees c in an atmosphere of 3% co2 concentration and a relative humidity of 75-80%. under these conditions, 91% of the engorged nymphae attained a mean weight of 6-11 mg, and an average of 93% of those nymphae moulte ... | 1995 | 11023410 |
| cutaneous basophil associated resistance to ectoparasites (ticks). electron microscopy of rhipicephalus appendiculatus larval feeding sites in actively sensitised guinea pigs and recipients of immune serum. | electron microscopy has been used to monitor cellular activity in dermal lesions elicited by larval rhipicephalus appendiculatus feeding on actively sensitised guinea pigs and recipients of immune serum. the early primary response is characterised by mononuclear cells, many of which appear to be activated fibroblasts. collagen deposition is enhanced as the reaction progresses. granulocytes of all types appear in the lesion between 18 and 96 hr but they show no evidence of degranulation. free, me ... | 1983 | 6834174 |
| transmission of theileriosis in the traditional farming sector in the southern province of zambia during 1995-1996. | the incidence of first contact with the protozoan theileria parva was determined in three traditional cattle herds in the southern province of zambia in 1995 and 1996. the majority of first contacts occurred during the dry season in june, july and august, at a time of nymphal activity and in the absence of rhipicephalus appendiculatus adults, indicating that larva to nymph transmission plays a more prominent role than nymph to adult transmission under the prevailing conditions. | 2000 | 11059039 |
| natural attraction of livestock ticks by the leaves of a shrub. | during examination of leaves of different plants on rusinga island, kenya, ticks were commonly found on the leaves of a plant identified as acalypha fruticosa forsk. var. villosa hutch (euphorbiaceae). larvae of rhipicephalus appendiculatus were the predominant ticks encountered, found quiescent on the undersurface of the leaves. laboratory investigations showed that significant numbers of ticks were attracted by odours from this plant. it was concluded that the leaves of a. fruticosa are attrac ... | 1994 | 7941035 |
| cross-reactivity between hard tick antigens. | 1. the present study was carried out to determine the target cells and tissues for anti-tick immunoglobulins using an indirect immunohistochemical technique. 2. sections in triplicate prepared from unfed ticks rhipicephalus appendiculatus, r. evertsi and amblyomma variegatum were used to assess the cross-reactivity of serum from guinea pigs naturally infested with these tick species or immunized against them. 3. the sections showed slight (+) to strong ( +) labelling of several structures in the ... | 1994 | 8081294 |
| laboratory evaluation of pathogenicity of entomogenous nematodes to african tick species. | five strains of entomogenous nematodes, steinernema carpocapsae strains dd, mexican, sr, and heterorhabditis bacteriophora strains 1s5 and hp88, were tested for their pathogenicity to various developmental stages of five african tick species namely; rhipicephalus appendiculatus, r. evertsi, amblyomma variegatum, a. gemma, and boophilus decoloratus. in engorged female r. appendiculatus, all nematodes at a concentration of 1,000 infective juveniles (ij)/dish, except s. carpocapsae mexican strain, ... | 2000 | 11193637 |
| parasites of domestic and wild animals in south africa. xxxviii. ixodid ticks collected from 23 wild carnivore species. | ixodid ticks were collected from 104 wild carnivores belonging to 23 species in various nature reserves and on several farms in all nine provinces of south africa. seven feral cats in a nature reserve were also examined. twenty-four tick species belonging to seven genera were recovered and identified. amongst these ticks we consider the adults of haemaphysalis leachi, haemaphysalis spinulosa, haemaphysalis zumpti, ixodes rubicundus, rhipicentor nuttalli, rhipicephalus simus and rhipicephalus tur ... | 2000 | 11206391 |
| immunoglobulin-binding proteins in ticks: new target for vaccine development against a blood-feeding parasite. | humans have a long history of trying to control ticks. at first, attempts focused on modifying the habitat, whereas later efforts relied heavily on the use of chemicals. current research is directed at finding a vaccine against ticks. a strategy of targeting 'concealed antigens' succeeded with the first commercialised vaccine against the cattle tick boophilus microplus. however, vaccine development against other tick species appears unsatisfactory to date. vaccination depends on a specific antib ... | 1999 | 11212356 |
| antibody responses to map 1b and other cowdria ruminantium antigens are down regulated in cattle challenged with tick-transmitted heartwater. | serological diagnosis of heartwater or cowdria ruminantium infection has been hampered by severe cross-reactions with antibody responses to related ehrlichial agents. a map 1b indirect enzyme-linked immunosorbent assay that has an improved specificity and sensitivity for detection of immunoglobulin g (igg) antibodies has been developed to overcome this constraint (a. h. m. van vliet, b. a. m. van der zeijst, e. camus, s. m. mahan, d. martinez, and f. jongejan, j. clin. microbiol. 33:2405-2410, 1 ... | 2001 | 11238227 |
| tick-theileria interactions in response to immune activation of the vector. | watt, d. m., walker, a. r., lamza, k. a., and ambrose, n. c. 2001. tick-theileria interactions in response to immune activation of the vector. experimental parasitology 97, 89-94. immune mechanisms towards the haemoprotozoan parasite theileria parva were investigated in their tick vector, rhipicephalus appendiculatus. the exoskeletons of adult ticks were initially pierced with bacteria-coated, saline-coated, or sterile dry glass needles. haemolymph was extracted from the ticks at 6, 24, 48, and ... | 2001 | 11281705 |
| contrasting effects of sera from rabbits and cattle infested with ticks on the in vitro feeding performance of the tick rhipicephalus appendiculatus. | the in vitro feeding activity of partially engorged rhipicephalus appendiculatus (neumann) (acari: ixodidae) females fed on sera from uninfested hosts was compared to that of ticks fed serum of hosts which had previously been infested with ticks. although ticks fed best on sera from bovid hosts which had no prior exposure to this ectoparasite, two infestations of a bovid had no significant effect on the acceptability of its serum. in contrast, ticks fed sera from rabbits which had twice been inf ... | 1993 | 8333141 |
| entomogenous fungi as promising biopesticides for tick control. | when ticks were sealed in nylon tetrapacks and infected with the entomogenous fungi, beauveria bassiana and metarizium anisopliae and maintained in potted grass in the field, the fungal oil formulations (10(9) conidia per ml) induced 100% mortality in larvae of rhipicephalus appendiculatus and amblyomma variegatum, whereas mortalities in nymphs varied between 80-100% and in adults 80-90%. the aqueous formulations (10(9) conidia per ml) induced mortalities of 40-50% and reductions in egg hatchabi ... | 2000 | 11354619 |
| salivary gland extract of rhipicephalus appendiculatus ticks inhibits in vitro transcription and secretion of cytokines and production of nitric oxide by lps-stimulated ja-4 cells. | there is increasing evidence that compounds in tick saliva and salivary gland extract (sge) have a suppressive effect on host immunity and that tick-borne pathogens exploit this situation to their benefit thus causing diseases. we have demonstrated that sge derived from rhipicephalus appendiculatus ticks has a suppressive effect on a macrophage like cell line, ja-4, in terms of secretion as well as mrna transcription of three cytokines. percent suppression of cytokine secretion by ja-4 cells cul ... | 2001 | 11445155 |
| evidence for the utility of the bm86 antigen from boophilus microplus in vaccination against other tick species. | the bm86 antigen, as originally identified in boophilus microplus, is the basis of commercial tick vaccines against this tick species. the potential for using this antigen or homologues of the antigen in vaccination against other tick species has been assessed. we have conducted vaccine trials in cattle using the b. microplus-derived recombinant bm86 vaccine (tickgard) using pairs of vaccinated calves and control calves. these were infested with b. microplus and boophilus decoloratus larvae simu ... | 2001 | 11523920 |
| rescue of recombinant thogoto virus from cloned cdna. | thogoto virus (thov) is a tick-transmitted orthomyxovirus with a genome consisting of six negative-stranded rna segments. to rescue a recombinant thov, the viral structural proteins were produced from expression plasmids by means of a vaccinia virus expressing the t7 rna polymerase. genomic virus rnas (vrnas) were generated from plasmids under the control of the rna polymerase i promoter. using this system, we could efficiently recover recombinant thov following transfection of 12 plasmids into ... | 2001 | 11533190 |
| natural antibody affects survival of the spirochete borrelia burgdorferi within feeding ticks. | natural antibodies are those immunoglobulin molecules found in mammalian serum that arise in the absence of exposure to environmental pathogens and may comprise an early host defense against invading pathogens. the spirochete borrelia burgdorferi first encounters natural antibodies when its arthropod vector, ixodes scapularis, begins feeding on a mammalian host. natural antibodies may therefore have an impact on pathogens within blood-sucking vectors, prior to pathogen transmission to the mammal ... | 2001 | 11553590 |
| anti-interleukin-8 activity of tick salivary gland extracts. | interleukin-8 (il-8) is one of many mammalian chemokines (chemotactic cytokines) that direct mammalian inflammatory and immune cells to sites of injury and infection. chemokines are produced locally and act on leucocytes through selective receptors. the principal role of il-8 is to control the movement and activity of neutrophils. to date, several tick species have been shown to modulate the production or activity of certain cytokines but none of these are chemokines. using an il-8 specific elis ... | 2001 | 11589777 |
| feeding aggregation of the tick rhipicephalus appendiculatus (ixodidae): benefits and costs in the contest with host responses. | gregariousness can be advantageous in interspecific competition while intraspecific competition may favour solitude. we examined feeding behaviour of the ixodid tick, rhipicephalus appendiculatus, in the context of interspecific (tick-host) and intraspecific (tick-tick) competition. such competition is mediated through host rejection responses to tick infestation to which ticks respond by secreting immunodulatory saliva. we observed that group feeding adults increased their blood-feeding rate, r ... | 2001 | 11719955 |
| epidemiological observations of zimbabwean theileriosis: disease incidence and pathogenicity in susceptible cattle during rhipicephalus appendiculatus nymphal and adult seasonal activity. | fifty-nine hereford cattle susceptible to tick-borne diseases were used as tracer animals to assess the tick challenge and pathogenicity of theileria parva under field conditions in zimbabwe. they were moved periodically in groups of five to three commercial farms (one group consisted of four) during seasons of rhipicephalus appendiculatus nymphal and adult activity. all tracer cattle were herded together with the farm cattle but were not dipped. the nymphal tick counts were high on two of the f ... | 2001 | 11769350 |
| exposure of cattle immunized with different stocks of theileria parva to buffalo-associated theileria challenge on two game parks in zimbabwe. | eight cattle immunized with cattle-derived theileria parva boleni stabilate together with six susceptible controls were released in dombawera game park on the highveld of zimbabwe. this coincided with rhipicephalus appendiculatus nymphal activity. the cattle grazed together with african buffaloes (syncerus caffer) and were not treated against tick infestation. the nymphal tick infestation was high, and seven of the eight immunized cattle and three of the controls had severe and fatal reactions. ... | 2001 | 11769351 |
| laboratory and field investigations into the theileria parva carrier-state in cattle in zimbabwe. | the theileria parva carrier-state in cattle on commercial farms on zimbabwe was investigated using parasitological and serological methods. the proportion of cattle showing theileria piroplasms on two farms, which had recent histories of disease outbreaks, were 64% (n = 106, total of heifers and weaned calves examined) and 71.5% (n = 60) while the proportion of t. parva antibodies for the same animals were 59% and 98.5%, respectively. on four farms where no cases of the disease occurred for over ... | 2001 | 11769352 |
| climate, satellite imagery and the seasonal abundance of the tick rhipicephalus appendiculatus in southern africa: a new perspective. | recent predictive models for the distribution of the african tick rhipicephalus appendiculatus neumann, based on the computer packages climex and bioclim and data derived from meteorological satellites, and for the seasonal dynamics of the same tick using the computer simulation models ecfxpert and t3host, all have their limitations. statistical analysis of the relationships between the seasonal abundance of all three life stages of this tick and climatic and satellite-derived data from five sit ... | 1993 | 8369559 |
| ixodid ticks (acari: ixodidae) and livestock production: effect of varying acaricide treatments on ticks and productivity in east coast fever-immunized weaner and dairy cattle. | in a pilot trial to evaluate cost-effective methods of acaricide application, east coast fever-immunized weaner and dairy cattle were subjected to varying tick control regimens. all experimental cattle were maintained under the same extensive system of management. their monthly tick load, packed cell volumes, incidence of blood protozoans, weight changes, and daily milk production were noted. apart from rhipicephalus appendiculatus neumann, other tick species found in the study site were r. pulc ... | 1993 | 8510109 |
| immunity induced by vaccination with rhipicephalus appendiculatus salivary gland antigens does not augment protective immunity acquired naturally by exposing rabbits to adult ticks. | a study was conducted using rabbits to ascertain the effects of immunity induced with salivary gland antigens (sga) on naturally acquired host resistance, which was confirmed by exposing groups of rabbits to adult rhipicephalus appendiculatus (neumann) ticks. a reciprocal experiment was conducted to establish the effect of naturally acquired resistance on vaccination with sga. after the acquisition of resistance by either method of vaccination, rabbits were then challenged with the 3 life stages ... | 1996 | 8699449 |
| theileria parva epidemics: a case study in eastern zambia. | this paper presents the results of the follow-up of three sentinel herds between 1994 and 2000 during an east coast fever (ecf) epidemic in eastern zambia. the animals of the sentinel herds were closely monitored clinically and serologically together with detailed rhipicephalus appendiculatus counts. peaks of disease incidence occurred in the rainy season (december-february) and the dry months of may-july with nymph-to-adult tick transmission dominating the infection dynamics. a second wave of a ... | 2002 | 12072213 |
| ixodid ticks on indigenous goats owned by small-scale farmers in four communal grazing areas in south africa. | indigenous goats belonging to small-scale farmers in 4 communal grazing areas in south africa were sampled for ixodid ticks during the period september 1991 to may 1993. three of these areas were in the north west province (rietgat, madinyane and bethany), and one in mpumalanga province (geluk). no tick control was practised unless requested by the owners. seven ixodid tick species, of which the majority were immature ticks, were collected from the goats in north west province. amblyomma hebraeu ... | 2002 | 12088070 |
| rickettsia aeschlimannii: a new pathogenic spotted fever group rickettsia, south africa. | | 2002 | 12141981 |
| salivary fluid secretion in the ixodid tick rhipicephalus appendiculatus is inhibited by thogoto virus infection. | adult rhipicephatus appendiculatus ticks, infected with thogoto (tho) virus or control, were fed on guinea pigs and removed at intervals throughout the feeding cycle. salivary fluid secretion was measured by an in vitro technique. the salivary glands of infected, partially-fed ticks secreted fluid in vitro at about 75% the rate of controls, but the difference between infected and controls among engorged ticks was not statistically significant. basal and da-stimulated levels of cyclic amp (camp) ... | 2001 | 12171274 |
| studies on theileria and babesia infecting live and slaughtered animals in al arish and el hasanah, north sinai governorate, egypt. | during the year 2001, a total of 475 sheep, 200 goats, 135 cattle and 190 camels in el arich city and el hassanah center were examined for babesia ovis and theileria ovis. blood films were taken from the vein of the ear. meanwhile, the animals were examined for tick infestations. b. ovis and th. ovis were detected in 13 (2.7%), and 14 (2.9%) sheep, 14 (7.0%), and 15 (7.5%) goats, 13 (9.6%), and 11 (8.1%) cattle and 18 (9.5%), and 24 (12.6%) camels respectively. on the other hand, double infectio ... | 2002 | 12214937 |
| acaricide resistance profiles of single- and multi-host ticks from communal and commercial farming areas in the eastern cape and north-west provinces of south africa. | a field study (february 2000 to august 2001) was conducted on communal and commercial farms in the eastern cape and north-west provinces of south africa to detect the levels of tick resistance to commonly used acaricides. the larvae obtained from engorged females of the one-host tick boophilus decoloratus, the two-host tick rhipicepalus evertsi evertsi and the three-host ticks amblyomma hebraeum and rhipicephalus appendiculatus were tested against various concentrations of amitraz, chlorfenvinph ... | 2002 | 12234005 |
| immunisation against theileria parva in eastern zambia: influence of maternal antibodies and demonstration of the carrier status. | immunisation of calves by the infection and treatment method (i & t) has been extensively used in the eastern province of zambia to control east coast fever (ecf), a protozoan tick-borne disease. this paper presents the results of a field longitudinal study, which included a total of 148 angoni calves. after immunisation against ecf, they were monitored for a full rainy season, coinciding with the main peak of activity of the vector of theileria parva, the tick rhipicephalus appendiculatus. dysi ... | 2002 | 12446089 |
| distribution and phenology of ixodid ticks in southern zambia. | distribution data for epidemiologically important ticks (acari: ixodidae) in the southern province of zambia, one of the main cattle areas of the country, are presented. boophilus microplus (canestrini) was not recorded in southern zambia, whereas boophilus decoloratus (koch) is present throughout the area. new distribution patterns for less economically important ixodid ticks are also discussed. southern zambia is a transition zone because it is the most northern area in africa where mixed rhip ... | 2002 | 12510896 |
| ixodid ticks on cattle belonging to small-scale farmers at 4 communal grazing areas in south africa. | ixodid ticks were collected during the period september 1991 to august 1993 from cattle belonging to small-scale farmers utilising 4 communal grazing areas. three of these were in north west province and 1 in mpumalanga province, south africa. ten tick species were collected in north west province and 7 in mpumalanga. the adults of amblyomma hebraeum, rhipicephalus appendiculatus and rhipicephalus evertsi evertsi were most numerous in north west province, while in mpumalanga boophilus decoloratu ... | 2002 | 12515294 |
| four serine proteinase inhibitors (serpin) from the brown ear tick, rhiphicephalus appendiculatus; cdna cloning and preliminary characterization. | while development of an anti-boophilus microplus vaccine is advanced and practical, work on other economically important ticks such as rhipicephalus appendiculatus is still in its infancy. guess pcr primers, designed from a consensus amino acid sequence (navykfg) motif were used with rapid amplification of cdna ends (race) to clone four cdnas encoding serine proteinase inhibitors (serpin) from the brown ear tick rhipicephalus appendiculatus. the four genes designated as r. appendiculatus serpin ... | 2003 | 12535684 |
| evaluation of pcr to detect theileria parva in field-collected tick and bovine samples in tanzania. | the ability of pcr to detect infections of theileria parva, the cause of east coast fever, in field-collected tick and bovine samples from tanzania was evaluated. pcr-detected infection prevalence was high (15/20, 75%) in unfed adult rhipicephalus appendiculatus ticks that fed as nymphs on an acutely-infected calf, but low (22/836, 2.6%) in unfed adult r. appendiculatus collected from field sites in tanzania. tick infection prevalence was comparable to that in previous studies that used salivary ... | 2003 | 12591193 |
| ixodid ticks feeding on humans in south africa: with notes on preferred hosts, geographic distribution, seasonal occurrence and transmission of pathogens. | this paper records the identities of 558 ixodid ticks feeding on 194 humans in south africa. these ticks belonged to 20 species in six genera and those most frequently encountered were amblyomma hebraeum, haemaphysalis leachi, hyalomma marginatum rufipes, hyalomma truncatum, rhipicephalus appendiculatus, rhipicephalus gertrudae and rhipicephalus simus. with the exception of the larvae of r. appendiculatus, the incidents of these ticks feeding on humans correlated well with their seasonal occurre ... | 2002 | 12593517 |
| mating, male ixodes scapularis express several genes including those with sequence similarity to immunoglobulin-binding proteins and metalloproteases. | we created a cdna library from mating, male ixodes scapularis ticks and screened the library with a subtracted probe to eliminate genes common to feeding female and mating male i. scapularis ticks. a total of seven unique cdnas were identified in this screen. one cdna had sequence similarity to the igbp-mc gene from rhipicephalus appendiculatus, and another cdna potentially encodes a protein with similarity to metalloproteases. rt-pcr, using rna isolated from male and female i. scapularis ticks, ... | 2002 | 12593519 |
| the impact of ixodiphagus hookeri, a tick parasitoid, on amblyomma variegatum (acari: ixodidae) in a field trial in kenya. | in an experiment to investigate the effect of the tick parasitoid, ixodiphagus hookeri, on tick numbers on cattle, 150000 parasitoids were released over a period of 1 year in a field where ten cattle infested with multiple tick species were kept. amblyomma variegatum was reduced from 44 to two ticks per animal while rhipicephalus appendiculatus increased over the time of parasitoid release. during the time of release 51% of the nymphs of a. variegatum collected from the animals were parasitized. ... | 1997 | 9080682 |
| the effects of the brown ear-tick, rhipicephalus appendiculatus, on milk production of sanga cattle. | lactating sanga cows of the mashona breed from zimbabwe, receiving either a low or high level of nutritional supplement, were exposed to two levels of infestation of adults of the brown ear-tick, rhipicephalus appendiculatus in the highveld of zimbabwe. the effect of the ticks on the milk yield was measured over an 11-week period during the rainy season from january to april 1986. a technique in which calves were weighed before and after suckling was used to estimate milk yield. there were signi ... | 1997 | 9226644 |
| survival of theileria parva in its nymphal tick vector, rhipicephalus appendiculatus, under laboratory and quasi natural conditions. | groups of nymphal rhipicephalus appendiculatus muguga, having a mean of 1 or 9 theileria parva muguga-infected salivary gland acini per tick, were kept under quasi-natural conditions at an altitude of 1950 m or 20 degrees c at a relative humidity of 85% in the laboratory and their survival and infection prevalence and abundance determined over time. theileria parva infections for both categories of ticks survived in the nymphal ticks for 50 or 26 weeks post salivary gland infection under quasi-n ... | 2003 | 12866795 |
| rickettsia aeschlimannii in spain: molecular evidence in hyalomma marginatum and five other tick species that feed on humans. | | 2003 | 12899141 |
| internal and external mycoflora of the american dog tick, dermacentor variabilis (acari: ixodidae), and its ecological implications. | scopulariopsis brevicaulis, the anamorph of microascus brevicaulis (microascaceae, ascomycota), has been identified in the body contents of the tick dermacentor variabilis. after topical application of the fungal inoculum, tick mortality was marked. this is the first account describing the internal mycoflora of d. variabilis with a novel technique used to recover potential biological control agents. | 2003 | 12902299 |
| the effects of the brown ear-tick, rhipicephalus appendiculatus, on milk production in dairy cattle. | the effect is reported of artificially controlled levels of infestation with adults of rhipicephalus appendiculatus on the milk yield of twenty commercial bos taurus dairy cattle on a high plane of nutrition and eighteen crossbred b.taurus x sanga cattle on a lower plane of nutrition on the highveld of zimbabwe. the results showed no significant effect on milk yield of infestations averaging twenty engorging ticks per animal per day, despite severe ear damage in some animals. they indicate that ... | 1997 | 9226645 |
| climate change decreases habitat suitability for some tick species (acari: ixodidae) in south africa. | models predicting current habitat availability for four prominent tick species in africa (boophilus decoloratus, amblyomma hebraeum, rhipicephalus appendiculatus and hyalomma truncatum) were constructed using remotely sensed information about abiotic variables and a point-to-point similarity metric. year-to-year variations in the forecasted habitat suitability over the period 1983-2000 show a clear decrease in habitat availability, which is attributed primarily to increasing temperature in the r ... | 2003 | 12967169 |
| parasites of domestic and wild animals in south africa. xli. arthropod parasites of impalas, aepyceros melampus, in the kruger national park. | ectoparasites were collected from impalas, aepyceros melampus, at four localities within the kruger national park, namely skukuza, in the biyamiti region, crocodile bridge and pafuri. animals were also examined at skukuza during a severe drought and at skukuza and pafuri towards the end of a second drought. parasite burdens were analysed in relation to locality, sex, age class, month and drought. the impalas were infested with 13 ixodid ticks species, including two that were identified only to g ... | 2003 | 12967174 |
| rhipicephalus appendiculatus and east coast fever in tanganyika. | | 1961 | 13742371 |
| cyclic development and longevity of theileria parva in the tick rhipicephalus appendiculatus. | | 1964 | 14242265 |
| in vitro growth of tick tissues (rhipicephalus appendiculatus neumann, 1901). | | 1962 | 14470381 |
| immunogenicity of ehrlichia ruminantium grown in tick cell lines. | ehrlichia (previously cowdria) ruminantium, the pathogen which causes heart-water in domestic and wild ruminants, can now be propagated in cell lines from one vector (amblyomma variegatum) and five non-vector (ixodes scapularis, i. ricinus, boophilus decoloratus, b. microplus and rhipicephalus appendiculatus) tick species. e. ruminantium isolates from west and south africa and the caribbean vary in their cell line preference, growth patterns and immunogenic capability. in laboratory trials, cert ... | 2002 | 14570129 |
| helminths and arthropods of black and white rhinoceroses in southern africa. | helminths and arthropods were collected and quantified from two black rhinoceroses (diceros bicornis bicornis) and one white rhinoceros (ceratotherium simum), and ticks from an additional four black and two white rhinoceroses in southern africa. the helminths of a black rhinoceros from the republic of south africa and one from namibia were quantitatively measured and recorded for each compartment of the alimentary tract. probstmayria vivipara was the most abundant parasite in each animal. a rece ... | 1997 | 9249695 |
| survival of theileria parva-infected adult rhipicephalus appendiculatus under laboratory and quasi-natural conditions. | adult rhipicephalus appendiculatus muguga, having high or low intensities of theileria parva muguga infection in their salivary glands, were exposed to 20 degrees c and 85% relative humidity in the laboratory or quasi-natural conditions. survival of the ticks and t. parva infections in their salivary glands was then monitored over a two year period. ticks, having an average infection level of 2 infected acini per female, survived for up to 70 or 106 weeks after moulting under the laboratory or q ... | 2003 | 14635820 |
| a generic population model for the african tick rhipicephalus appendiculatus. | we present a simulation population model for the african tick rhipicephalus appendiculatus, based on previous analyses of the mortality factors most closely correlated with observed population changes at 11 sites in equatorial and south africa. the model incorporates temperature-dependent rates of egg production and development, climate-driven density-independent mortality rates, particularly during the adult-larval stage, and density-dependent regulation of both nymphs and adults. diapause is a ... | 1997 | 9300464 |
| tick histamine-binding proteins: isolation, cloning, and three-dimensional structure. | high-affinity histamine-binding proteins (hbps) were discovered in the saliva of rhipicephalus appendiculatus ticks. their ability to outcompete histamine receptors indicates that they suppress inflammation during blood feeding. the crystal structure of a histamine-bound hbp, determined at 1.25 a resolution, reveals a lipocalin fold novel in containing two binding sites for the same ligand. the sites are orthogonally arranged and highly rigid and form an internal surface of unusual polar charact ... | 1999 | 10360182 |
| ehrlichia ruminantium grows in cell lines from four ixodid tick genera. | continuous cell lines from the ticks amblyomma variegatum, boophilus decoloratus, boophilus microplus, hyalomma anatolicum anatolicum, ixodes scapularis, ixodes ricinus and rhipicephalus appendiculatus were tested for ability to support growth of the rickettsial pathogen ehrlichia (previously cowdria) ruminantium. five e.ruminantium isolates, from west africa, south africa and the french west indies, were used. twelve tick cell lines were inoculated with e.ruminantium derived either from culture ... | 2004 | 15053931 |
| comparative studies on the infectivity of theileria parva in ticks fed in vitro and those fed on cattle. | nymphs of the brown ear tick, rhipicephalus appendiculatus, were fed on heparinised bovine blood infected with theileria parva parasites in an in vitro feeding system consisting of rabbit skin membranes. the main feeding and development parameters such as the mean attachment rate, feeding duration and engorgement weights of membrane-fed ticks were not significantly different from nymphs fed on cattle. the moulting rate was also comparable although a slight significant difference was observed. as ... | 2004 | 15139272 |
| identification of four genes expressed by feeding female ixodes scapularis, including three with sequence similarity to previously recognized genes. | we created a cdna library from feeding, female ixodes scapularis ticks and screened the library with a subtracted probe to eliminate most genes common to feeding female and mating male i. scapularis ticks. four unique genes were identified in this screen. one gene, is 9, (represented by 16 cdnas) was more highly expressed in female ticks. this gene encodes a putative glycine-rich protein, which matched a number of glycine-rich proteins including attachment cement proteins from rhipicephalus appe ... | 2004 | 15139276 |
| diapause induction in adults of three rhipicephalus appendiculatus stocks. | newly-moulted adults of three rhipicephalus appendiculatus stocks, originating from kenya, zambia and zimbabwe, were kept in different photoperiods (12h:12h, 13h:11h and 14h:10h light:dark). the stock originating from kenya showed almost no behavioural diapause in any of these day lengths, whereas virtually all individuals of the zimbabwean stock entered a behavioural diapause irrespective of day length. adults from the eastern province of zambia, a transition zone between the multivoltine pheno ... | 1999 | 10737730 |
| cloning, expression and partial characterization of a haemaphysalis longicornis and a rhipicephalus appendiculatus glutathione s-transferase. | the ticks haemaphysalis longicornis and rhipicephalus appendiculatus are important parasites worldwide. the current method for control of cattle ticks involves the use of chemicals. nevertheless, parasite resistance is an ever increasing global problem. glutathione s-transferases (gsts) play a central role in detoxication of xenobiotic and endogenous compounds. several authors have noted that an increase in gst activity is associated with resistance to insecticides and acaricides. in the present ... | 2004 | 15157234 |
| molecular individuality: polymorphism of salivary gland proteins in three species of ixodid tick. | pooled tissue samples are frequently used in biochemical studies involving parasites in order to ensure that there is sufficient material for experimentation. a pooled sample is considered to represent the overall phenotypic characteristics of the investigated population. however, this will not be the case if there is a significant degree of molecular polymorphism among individuals in the sampled population. here we demonstrate marked differences in the protein profile of salivary glands among i ... | 1999 | 10737731 |
| non-systemic infection in rhipicephalus appendiculatus ticks. | | 1997 | 15275093 |
| artificial feeding of ixodid ticks. | ixodid ticks are economically important as they cause direct damage to livestock and are vectors of several pathogens that cause diseases in humans and animals. some of the important tick-borne pathogens of livestock are theileria parva, t. annulata, babesia bigemina, b. bovis, anaplasma marginale and cowdria ruminantium. these pathogens are responsible for causing enormous losses in livestock. identification of factors that influence transmission and development of these pathogens in ticks will ... | 1996 | 15275192 |
| susceptibility of mosquito and tick cell lines to infection with various flaviviruses. | the genus flavivirus consists of more than 70 virus species and subtypes, the majority of which are transmitted by mosquitoes or ticks, although some have no known vector (nkv). the ability of these viruses to infect cultured cells derived from mosquito or tick species offers a useful insight into the suitability of such vectors to harbour and replicate particular viruses. we undertook a comparative study of the susceptibility of mammalian vero cells, a clonal mosquito cell line (c6/36) and rece ... | 2004 | 15347394 |
| climate, vegetation and the distribution of rhipicephalus appendiculatus in africa. | | 1990 | 15463309 |
| genes transcribed in the salivary glands of female rhipicephalus appendiculatus ticks infected with theileria parva. | we describe the generation of an auto-annotated index of genes that are expressed in the salivary glands of four-day fed female adult rhipicephalus appendiculatus ticks. a total of 9162 est sequences were derived from an uninfected tick cdna library and 9844 ests were from a cdna library from ticks infected with theileria parva, which develop in type iii salivary gland acini. there were no major differences between abundantly expressed ests from the two cdna libraries, although there was evidenc ... | 2004 | 15475305 |
| endemic stability for theileria parva infections in ankole calves of the ankole ranching scheme, uganda. | a population-based study was carried out on the ankole ranching scheme in south-west uganda with the aim of determining the endemic status of theileria parva infections. for this purpose, the age-related sero-prevalence of t. parva and the specific calf mortality associated with the parasite were assessed. blood samples were collected from 931 ankole calves of up to 12 months of age from 81 randomly selected herds. the relationship between rainfall pattern and whole-body rhipicephalus appendicul ... | 2004 | 15580767 |
| molecular cloning and sequence analysis of cdnas encoding for boophilus microplus, haemaphysalis longicornis and rhipicephalus appendiculatus actins. | the nucleotide and deduced amino acid sequences of the actins from ticks, boophilus microplus, haemaphysalis longicornis and rhipicephalus appendiculatus, have been determined. nucleotide sequence analysis showed open reading frames of 1128-nucleotide-long encoding proteins of 376 amino acids with a predicted molecular weight of 41.82 kda each. comparison between the nucleic acid and deduced amino acid sequences as well as structural and phylogenetic analyses of these genes confirmed the high si ... | 2004 | 15631908 |
| variation in body size in the tick complex rhipicephalus appendiculatus/rhipicephalus zambeziensis. | we examined the relationship between body size and the phenology of the tick complex rhipicephalus appendiculatus/rhipicephalus zambeziensis. these ticks transmit theileria parva in cattle. in africa, the body size of r. appendiculatus increases with latitude while the body size of the morphologically similar rhipicephalus zambeziensis is constant at two different latitudes. a larger body size is necessary once survival becomes a constraint. the most plausible explanation for the smaller r. appe ... | 2004 | 15707294 |
| risk factors for tick attachment to smallholder dairy cattle in tanzania. | a cross-sectional study was conducted in tanga and iringa regions of tanzania, and a longitudinal study in tanga, to investigate tick-control methods and other factors influencing tick attachment to the cattle of smallholder dairy farms. most farmers reported applying acaricides at intervals of 1-2 weeks, most used acaricides that require on-farm dilution and most farmers incorrectly diluted the acaricides. rhipicephalus appendiculatus and boophilus spp. ticks were those most-frequently encounte ... | 2004 | 15737429 |
| the prevalence of serum antibodies to tick-borne infections in mbale district, uganda: the effect of agro-ecological zone, grazing management and age of cattle. | between august and october 2000, a cross-sectional study was conducted in smallholder dairy farms in mbale district, uganda to assess the prevalence of ticks and tick-borne diseases under different grazing systems and agro-ecological zones and understand the circumstances under which farmers operated. a questionnaire was administered to obtain information on dairy farm circumstances and practices. a total of 102 farms were visited and sera and ticks were collected from 478 animals. sero-prevalen ... | 2004 | 15861224 |
| a cross-reactive tick cement antigen is a candidate broad-spectrum tick vaccine. | truncated constructs of 64p (64trps), a secreted cement protein from salivary glands of the tick rhipicephalus appendiculatus, provided cross-protection against rhipicephalus sanguineus and ixodes ricinus, apparently by targeting antigens in the midgut and salivary glands of adults and nymphs, causing mortality. tick feeding on 64trp-immunised animals stimulated local inflammatory immune responses (involving basophils, eosinophils, lymphocytes, mast cells, macrophages and dendritic-like cells) t ... | 2005 | 15913855 |
| artificial infection of rhipicephalus appendiculatus with theileria parva by percutaneous injection. | rhipicephalus appendiculatus nymphs were inoculated with fresh or cryopreserved blood containing theileria parva piroplasms, or with cell culture grown stages of t parva. the use of fresh blood was successful. cryopreserved blood containing dimethylsulphoxide (dmso), killed most nymphs after inoculation: dmso could be removed by slow dialysis, without destroying the infectivity of the blood. attempts to infect ticks by inoculating cell culture grown stages of t parva failed, even when large numb ... | 1980 | 6789418 |
| effects of combining the fungi beauveria bassiana and metarhizium anisopliae on the mortality of the tick amblyomma variegatum (ixodidae) in relation to seasonal changes. | the effect of formulation, fungal concentration, type and seasonal changes on the mortality of the tick amblyomma variegatum was investigated. a previous study demonstrated high pathogenicity of strains of the fungi beauveria bassiana and metarhizium anisopliae against the ticks rhipicephalus appendiculatus and amblyomma variegatum (kaaya et al. j invertebr pathol 1996; 67: 15-20). the present study was undertaken to explore possible additive or synergistic effects of the two fungi on a. variega ... | 2005 | 15983739 |
| rhipicephalus appendiculatus: larval feeding sites in guinea pigs actively sensitized and receiving immune serum. | histological analyses of larval rhipicephalus appendiculatus feeding sites in naive and actively sensitized guinea pigs were made at 6, 24, 48, 72, 96 hr post-tick attachment. as primary feedings progressed the cavity at the entrance of the ticks mouthparts into the uppermost dermis, and the surrounding cellular infiltrate (lesion) both increased. early (6 hr) lesions were dominated by eosinophils again predominated at 72 hr (44%), and finally basophils were dominant at 96 hr increased as tick f ... | 1983 | 6822283 |
| the effect of trypanosoma congolense infection on acquired immunity to the tick rhipicephalus appendiculatus. | | 1983 | 6882069 |
| the ecology of rhipicephalus zambeziensis and rhipicephalus appendiculatus (acarina, ixodidae) with particular reference to zimbabwe. | r. zambeziensis, like r. appendiculatus, is primarily a parasite of domestic and wild herbivores, and sometimes carnivores. both species occur in parts of east, central and southern africa, but they are not as a rule sympatric. in general, r. zambeziensis occurs in hotter, drier areas than does r. appendiculatus, especially along some of the great river valleys. in zimbabwe, r. zambeziensis is largely restricted to the northern, northwestern and southern parts of the country, whereas r. appendic ... | 1982 | 7185034 |
| a study of the diapausing behaviour of rhipicephalus appendiculatus and r. zambeziensis under quasi-natural conditions in zambia. | the diapausing behaviour of rhipicephalus appendiculatus was studied under quasi-natural conditions in the eastern province of zambia. newly-moulted adults of ticks indigenous to the study area entered a behavioural diapause when exposed to daylengths below a critical photoperiod, provisionally a daylength between 11 h 20 min and 11 h 45 min. in the eastern province of zambia the diapause was apparently not terminated by a long-day signal, but by a weakening of the photoperiodic maintenance of t ... | 1995 | 7548950 |
| repellent and acaricidal properties of ocimum suave against rhipicephalus appendiculatus ticks. | an oil extracted from the leaves of a tropical shrub ocimum suave was found to repel as well as kill all stages of the tick rhipicephalus appendiculatus. in an in vitro bioassay for the larvae, the lc50 of the oil in liquid paraffin was 0.024%. a 10% solution was found to kill all immatures and more than 70% of adults feeding on rabbits. rabbits were protected for 5 days against attaching larvae using a 10% solution. preliminary experiments undertaken with cattle kept in the field suggest that t ... | 1995 | 7621709 |
| immunisation of rabbits against the brown ear tick, rhipicephalus appendiculatus using tick haemolymph. | tick naive rabbits were immunised with haemolymph components from partially fed rhipicephalus appendiculatus adult ticks and subsequently challenged with all the developmental instars of the tick. the results obtained showed that the rabbits were rendered resistant to all the instars of the tick. however, the resistance was more pronounced in adult ticks than in the immature stages. the resistance was manifested as a reduction in the number of ticks that fed successfully to engorgement, reduced ... | 1994 | 7628248 |
| evidence for a mounting sex pheromone in the brown ear tick rhipicephalus appendiculatus, neuman 1901 (acari: ixodidae). | the presence of a mounting sex pheromone was demonstrated on the surface of fed female rhipicephalus appeniculatus. this pheromone, which is present on the female cuticle, allows the male to recognise the female. the pheromone was removed by cleaning the female in hexane, resulting in the loss of male mating behaviour in in vitro experiments. male mating behaviour was resumed when extract made from fed female cuticle was replaced on cleaned females. when the extract was transferred to inanimate ... | 1994 | 7628251 |
| isotopes as host blood markers to measure blood intake by feeding ticks (acari: ixodidae). | we have modified an experimental technique in which two different isotopes (cr51 and i125) were used simultaneously as blood markers for determining the amount of blood removed by feeding ticks. this method enables us to measure separately and directly the volumes of red blood cells and plasma in ticks and to calculate the ratio between the two parameters (concentrating ability). the concentration of red blood cells in nymphs of amblyomma hebraeum kock and rhipicephalus appendiculatus neumann an ... | 1994 | 7932595 |
| nitrophorins and related antihemostatic lipocalins from rhodnius prolixus and other blood-sucking arthropods. | recent gene sequence and crystal structure determinations of salivary proteins from several blood-sucking arthropods have revealed an unusual evolutionary relationship: many such proteins derive their functions from lipocalin protein folds. many blood-sucking arthropods have independently evolved the ability to overcome a host organism's means of preventing blood loss (called hemostasis). most blood feeders have proteins that induce vasodilation, inhibit blood coagulation, and reduce inflammatio ... | 2000 | 11058753 |
| ticks and tick-borne diseases: a vector-host interaction model for the brown ear tick (rhipicephalus appendiculatus). | an analytical model is derived for the interaction of the brown ear tick (rhipicephalus appendiculatus) with its hosts. such models are rare due to the complexity and lack of information on the entire stages of ticks life cycles. most models are simulations rather than analytical. the vector is categorized into a discrete number of compartments according to its life cycle. the starting model in this article consists of a system of differential equations with constant coefficients. a general mode ... | 2000 | 11084709 |
| assessing infestation risk by vectors. spatial and temporal distribution of african ticks at the scale of a landscape. | control of major livestock diseases in the tropics, such as theileriosis or trypanosomosis, is still largely based on the control of their vectors. understanding the distribution of vectors, such as ticks and tsetse flies, is needed in order to improve the efficiency and economical viability of control operations. technical improvements such as remote sensing and global information systems have allowed valuable improvements for the prediction of large-scale vector distribution (continental to na ... | 2000 | 11193624 |
| intra-stadial tick-borne thogoto virus (orthomyxoviridae) transmission: accelerated arbovirus transmission triggered by host death. | haematophagous insect vectors of arthropod-borne viruses (arboviruses) feed repeatedly. consequently, they can transmit arboviruses to more than one host during the same developmental stage (intra-stadial transmission). by contrast, ixodid ticks generally feed only once at each parasitic stage (larva, nymph, and adult) and hence they have only one opportunity for tickborne virus transmission per stadium (inter-stadial transmission). under natural conditions, tick-infested hosts may die (from dis ... | 2001 | 11315177 |
| molecular individuality and adaptation of the tick rhipicephalus appendiculatus in changed feeding environments. | the tick rhipicephalus appendiculatus neumann (acari: ixodidae) naturally infests many host species. however, the mechanisms that enable it to feed on such a wide range of hosts are unclear. one possibility is that a tick population maintains molecular (genotypic and/or phenotypic) diversity among individuals such that individuals vary in their competency in taking bloodmeals under different feeding conditions. as a first step in testing this hypothesis, we showed that the polymorphism of saliva ... | 2001 | 11776459 |