electron-microscopic studies on theileria ovis rodhain, 1916: development of kinetics in the gut of the vector tick, rhipicephalus evertsi evertsi neumann, 1897, and their transformation within cells of the salivary glands.gamogony of theileria ovis rodhain occurs within the gut of nymphs of the tick rhipicephalus evertsi evertsi neumann. after molting, spherical and ovoid parasites are found within the intestinal cells of the ticks. these stages are thought to be zygotes, because they undergo a transformation process leading ultimately (in 3 days) to the formation of a motile stage, the kinete, the fine structure of which is very similar to that of the ookinetes of the hemosporidia. the kinete leaves the gut cell ...1979119849
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 life cycle of the two-host tick rhipicephalus evertsi evertsi neumann, 1897, under laboratory conditions (acarina: ixodidae).the life cycle of rhipicephalus evertsi evertsi neumann, 1897, is discussed under the following headings: larval feeding; larval drop; nymphal feeding; nymphal drop; nymphal moulting; adult feeding; adult drop; preoviposition period; oviposition period and incubation. special attention has also been given to the development of both male and female reproductive organs, gametogensis and mating.1977614518
life cycle of the tick rhipicephalus evertsi evertsi neumann (acarina: ixodidae) under laboratory conditions.the preoviposition period of the tick rhipicephalus evertsi neumann maintained under laboratory conditions at 26 c was 6.1 +/- 0.38 days. the average number of eggs produced during the oviposition period was 10,400 +/- 397 (max. 13.307, min. 7,558). the greatest daily egg production was recorded on the 3rd day (1.107 eggs/female). the incubation period of eggs at 26 c was 24.8 +/- 1.37 and the feeding time of the larvae and nymphs (a two-host tick) was 17.2 +/- 0.14 days at 26 c. this tick repre ...1977864575
ticks from the african buffalo (syncerus caffer) in ngamiland, november 1972, 93 out of 100 african buffalo from 3 areas in ngamiland, botswana, were found to be infested with ticks. the tick species present and the percentage of buffalo infested by each were: hyalomma truncatum (63%), h. rufipes (54%), rhipicephalus evertsi evertsi (68%), r. tricuspis (11%), r. simus (4%) and boophilus decoloratus (1%). the mean number of ticks per animal was 8,6 (standard deviation +/-4,1), representing a mean of 6,5+/-3,4 male and 2,1+/-1,9 female ticks. the incidence ...1976940665
arsenic resistance in species of multi-host ticks in the republic of south africa and swaziland.a survey was made in the republic of south africa and swaziland to determine the incidence of arsenic resistance in multi-host ixodid ticks. arsenic resistant strains were found in the following species:- rihipicephalus appendiculatus, rhipicephalus evertsi, rhipicephalus capensis, amblyomma hebraeum and a species of hyalomma, tentatively identified as hyalomma rufipes. strains of haemaphysalis leachi, haemaphysalis silacea and ixodes pilosus were also tested.19751223285
arthropod parasites of springbok, gemsbok, kudus, giraffes and burchell's and hartmann's zebras in the etosha and hardap nature reserves, namibia.a total of 48 springbok, 48 gemsbok, 23 kudus and 6 giraffes were examined for ticks and lice, while 9 burchell's zebras and 6 hartmann's mountain zebras were examined only for ticks. springbok and gemsbok were shot in both the etosha national park in the north and the hardap nature reserve in the south of namibia. all the other animals were shot in the etosha national park. a total of 7 ixodid tick species and 8 lice species were recovered. the springbok carried few ticks. the adults of a rhipi ...19921297955
parasites of domestic and wild animals in south africa. xxx. ectoparasites of kudus in the eastern transvaal lowveld and the eastern cape province.sets of four kudus were shot and examined for arthropod parasites at approximately monthly intervals from april 1981 to march 1983 in the southern part of the kruger national park, eastern transvaal lowveld. these animals harboured 10 ixodid tick species of which boophilus decoloratus followed by amblyomma hebraeum were the most abundant. the seasonal abundances of these ticks and of amblyomma marmoreum, rhipicephalus appendiculatus, rhipicephalus evertsi evertsi and rhipicephalus zambeziensis w ...19921297956
parasites of domestic and wild animals in south africa. xxxi. adult ixodid ticks on sheep in the cape province and in the orange free state.four to 10 dorper sheep on each of 12 farms in the cape province and 3 farms in the orange free state were examined for adult ixodid ticks at approximately 2- to 4-weekly intervals over periods varying from 4 to 18 months, commencing during january, february or april 1989. the farms in the cape province were located in the north-west, south-west and south of the province. those in the orange free state were situated in the north-east and in the south. the sheep in the cape province harboured 10 ...19921297957
transmission and diagnosis of equine babesiosis in south africa.the transmission and prevalence of babesia equi and b. caballi are being studied. rhipicephalus evertsi mimeticus an ixodid tick from namibia was identified as a new vector of b. equi, however, r. turanicus, previously reported to be a vector, failed to transmit both b. equi and b. caballi in the laboratory. the accurate diagnosis of b. caballi is being investigated because the nature of its low level parasitaemia does not allow easy detection in thin blood smears, routinely used for diagnosis, ...19921343683
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
the effects of nutritional status of rabbits and sheep on their resistance to the ticks rhipicephalus evertsi evertsi and r. appendiculatus.rabbits and sheep were exposed to low- and high-protein diets and subsequently infested three times with adults of rhipicephalus appendiculatus and rhipicephalus evertsi evertsi. the mean weight of r.e. evertsi females which dropped from rabbits maintained on a high-protein diet decreased from 515.0 +/- 24.9 mg (naive) to 381.5 +/- 25.0 (second infestation) to 340.3 +/- 23.3 mg (third infestation) while the weight of ticks fed on animals which were exposed to a low-protein diet did not change si ...19921446570
the identification of a shared immunogen present in the salivary glands and gut of ixodid and argasid ticks.the identification of a 70-kda immunogen present in salivary gland extracts of several ixodid species, namely hyalomma truncatum (sweating-sickness-inducing (ss+) and non-inducing (ss-) strains), hyalomma marginatum rufipes and rhipicephalus evertsi evertsi, is reported. the immunogen was identified by western blots using a monoclonal antibody of the igm isotype directed against a 70-kda immunogen present in the salivary glands of (ss-) female h. truncatum ticks. cross-reactivity with the gut of ...19921446571
anaplasmosis in uganda. iii. parasitological and serological evidence of anaplasma infection in ugandan goats.randomly selected goat sera from north-western, central, and south-western regions of uganda were analyzed parasitologically and serologically for evidence of anaplasmosis. prevalence rates of 3.2% by parasitemia, 4.8% by card-agglutination test, and 12.9% by dot-elisa combined with western blotting were established. parasitologically positive samples were consistently serologically positive. positive samples were all from either the north-western or south-western regions of the country. goats i ...19921513596
development of resistance in laboratory animals to adults of the tick rhipicephalus evertsi evertsi.acquired resistance to adults of the two-host tick rhipicephalus evertsi evertsi neumann has been demonstrated in guinea-pigs and rabbits. four infestations of both hosts with r.e.evertsi adults resulted in a significant reduction in the mean weight of the engorged females. a decline in the mean weight of the female ticks was also observed in ticks which fed on a rabbit previously injected with serum taken from a rabbit resistant to r.e.evertsi. this suggests that humoral immunity may have an im ...19911768898
on the reaction of adult rhipicephalus evertsi mimeticus and hyalomma truncatum to horizontally incidenting optical radiation of various wavelengths ranges and different irradiances and to optical radiation of a sun-simulating wavelength spectrum.the valence of horizontally incidenting light/optical radiation for host-seeking-inclined ixodid ticks was investigated by exposing male and female adults of rhipicephalus evertsi mimeticus and hyalomma truncatum to narrow-band monochromatic radiation in the wavelength range of 300-801 nm at irradiances corresponding to an overcast to clear sunny day, a cloudy day and a full-moon night as well as to optical radiation of a sun-simulating wavelength spectrum of 190-2600 nm within a test chamber fr ...19911866424
viraemic transmission of crimean-congo haemorrhagic fever virus to order to determine the way in which vertebrates infected with crimean-congo haemorrhagic fever (cchf) virus and potential ixodid tick vectors interact in nature, immature and adult ticks of several species were fed on viraemic mammals and then assayed for virus content at varying times after feeding. cchf virus was not isolated from ticks of six species tested after feeding as adults and immature forms on sheep with viraemia of 10(2.5-3.2) ld 50/ml, nor from larval ticks fed on guinea-pigs an ...19911902186
parasites of domestic and wild animals in south africa. xxv. ixodid ticks on sheep in the north-eastern orange free state and in the eastern cape province.the tick burdens of 115 merino sheep, slaughtered over a period of 15 consecutive months on a farm in the north-eastern orange free state, were determined. a total of 7 ixodid and 1 argasid tick species were recovered and the seasonal abundances of boophilus decoloratus, hyalomma marginatum rufipes, margaropus winthemi and rhipicephalus evertsi evertsi were determined. one hundred and forty-nine merino sheep were slaughtered over periods varying from 10 to 25 months on 3 farms in eastern provinc ...19911923373
parasites of domestic and wild animals in south africa. xxvi. the mosaic of ixodid tick infestations on birds and mammals in the mountain zebra national park.sixteen species of ixodid ticks were collected over varying periods of time from 6 species of ground-frequenting birds and 15 species of small and large mammals in the mountain zebra national park, karoo, cape province. margaropus winthemi followed by rhipicephalus glabroscutatum and rhipicephalus evertsi evertsi were the most abundant species. the host preferences of 14 tick species and the seasonal abundances of 13 species were determined. small numbers of immature stages of only a few tick sp ...19911923374
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
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
seasonal abundance of ticks associated with indigenous goats on a northern transvaal farm.the 3 most abundant tick species on indigenous goats on a northern transvaal farm were found to be rhipicephalus evertsi evertsi, rhipicephalus appendiculatus and amblyomma hebraeum. three other tick species were present in small numbers. the economical and ecological importance of the ticks found on the goats, mainly in rural areas where chemical control of ticks is practically non-existant, is discussed. the high number of goats in the study area and the shift towards alternative methods of ti ...19912051439
efficacy of ivermectin delivered from an intraruminal sustained-release bolus against natural infestations of five african tick species on cattle.the efficacy of ivermectin delivered by an orally administered prototype sustained-release bolus over approximately 90 days was evaluated against natural infestations of five african tick species. twenty cattle, allocated by restricted randomization based on counts of standard boophilus decoloratus, were allocated to two groups and were either given an ivermectin bolus or designated as non-medicated controls. all cattle grazed a single pasture of native grasses for 20-40 days before treatment an ...19902267728
the isolation and transmission of an unidentified babesia sp. to cattle by hyalomma truncatum koch unidentified babesia sp. which causes a mild disease in cattle was isolated in a splenectomized ox that received pooled blood from field cattle. that this organism is pleomorphic and resembles babesia occultans makes it difficult to differentiate between these organisms microscopically. initially, it was suspected that this babesia could be b. occultans. several attempts to transmit this parasite transovarially with hyalomma marginatum rufipes, the vector of b. occultans, failed. continued ef ...19902293131
resistance of brahman and simmentaler cattle to southern african ticks.field collections of ticks from two breeds of cattle in the north western transvaal showed the common tick species to be rhipicephalus appendiculatus, amblyomma hebraeum, rhipicephalus evertsi evertsi and hyalomma marginatum rufipes. the number of these ticks was higher on simmentaler than on brahman cattle. correlation was found between the number of ticks on the cattle and their serum gamma globulin levels indicating an increase in the production of antibodies. similar correlation was also fou ...19902339000
the interaction between the immune response of rabbits to heterologous antigens and a primary infestation with rhipicephalus evertsi evertsi.rhipicephalus evertsi evertsi feeding on hosts inoculated with sheep red blood cells (srbc) and bovine serum albumin (bsa) suppressed the primary antibody response to the two antigens. in addition, while the ticks paralysed most hosts in the studies, fatality associated with this toxicosis occurred only in rabbits which had received srbc, either alone or with bsa. only those hosts inoculated with bsa developed any resistance against the ticks, manifested by a slight reduction of engorged weights ...19902345952
the effects of non-specifically activated immunity in rabbits on primary infestation with rhipicephalus evertsi evertsi.the secondary antibody response to sheep red blood cells and bovine serum albumin (bsa) was measured in rabbits infested with adult rhipicephalus evertsi evertsi. the response was reduced (particularly for bsa) but still displayed anamnestic characteristics. resistance against ixodid ticks associated with antibodies detected by gel diffusion and enzyme linked immunosorbent assay techniques early in the primary challenge was acquired by the immunized hosts only. this suggests that a non-specifica ...19902345953
on the morphology and organization of the eye of unfed adult rhipicephalus evertsi mimeticus (acari: ixodidae).investigations by scanning and transmission electron microscopy and freeze-etching revealed that eyes of adult rhipicephalus evertsi mimeticus consist of a lens and photoreceptor cells, which are separated by an acellular layer and the hypodermis. the lens contains numerous pore channels, which open beneath the epicuticula of the outer portion, converge uninterrupted to the inner closure and end in approximately 420 pore fields. the inner closure of the lens is formed as a deep circular invagina ...19902352920
resistance of brahman and hereford cattle to african ticks with reference to serum gamma globulin levels and blood composition.field collections of ticks from two breeds of cattle showed that the common species of ticks were amblyomma hebraeum, rhipicephalus appendiculatus and rhipicephalus evertsi evertsi. the density of these species was higher on hereford than on brahman cattle. the results also indicated that the density of immature stages of the above-mentioned ticks is higher on hereford than on brahman cattle. a positive correlation was found between the number of ticks on the cattle and the serum gamma globulin ...19872456184
experimental studies on the replication and transmission of crimean-congo hemorrhagic fever virus in some african tick african tick species were studied as potential vectors of crimean-congo hemorrhagic fever (cchf) virus. engorged nymphae of 4 ixodid species, hyalomma marginatum rufipes, h. truncatum, rhipicephalus evertsi mimeticus, and amblyomma hebraeum, were inoculated intracoelomically with cchf virus and assayed for virus content at varying times post-inoculation. the virus replicated in all 4 species, reaching maximum titers of 4.6-5.5(10) fluorescence focus units per ml on days 5-9 post-inoculatio ...19892494900
expression of acquired immunity to immature stages of the tick rhipicephalus evertsi evertsi by rabbits and guinea-pigs.acquired immunity in guinea-pigs and rabbits to immature stages of the two-host tick rhipicephalus evertsi evertsi neumann was demonstrated. repeated infestations of both hosts with larvae resulted in a significant reduction in the weight of later engorged nymphs. a sharp decline in the numbers of nymphs which successfully fed on both hosts was also observed. this study provides evidence for a gradual decrease in the mean weight of engorged nymphs towards the end of the detachment period suggest ...19892519645
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
[the efficacy of alphamethrin-impregnated ear tags against ticks].the efficacy of 3 kinds of alphamethrin-impregnated ear tags was tested against natural amblyomma hebraeum, boophilus decoloratus, rhipicephalus appendiculatus, and rhipicephalus evertsi evertsi infestations of cattle. one type of ear tag was also tested in combination with a tail band of similar material. ticks were counted macroscopically on their predilection sites. counts of b. decoloratus, r. appendiculatus, and r. e. evertsi on all trial animals diminished steadily during the first 7d afte ...19892607535
resistance to rhipicephalus evertsi evertsi in immunosuppressed rabbits.rabbits treated with goat anti-rabbit thymocyte serum acquired less resistance to rhipicephalus evertsi evertsi infestation than untreated controls. this inferior resistance was manifested as higher engorged weights of ticks and higher biotic potential, undue persistence of the ticks on the hosts and poor anti-tick antibody and delayed-type hypersensitivity responses. these observations highlight the significance of host t-cells in mediating resistance to ticks.19892672558
changes in the concentration of globulins in naive guinea pigs during feeding by the immature stages of rhipicephalus evertsi evertsi (acari: ixodidae).the weight of rhipicephalus evertsi evertsi neumann nymphs, which as larvae and nymphs completed the entire blood meal on the same individual guinea pig, was significantly lower than the weight of those that as larvae and nymphs fed on two separate naive hosts. nymphs of the latter category spent 1 wk (from unfed larvae to unfed nymphs) on one animal before their transfer to the second host to complete the blood meal. the albumin concentration of the host blood decreased and was related to the t ...19892769702
acquired resistance in rabbits to immature stages of rhipicephalus evertsi resistance, accompanied by demonstrable anti-tick antibodies, developed in groups of rabbits that were infested repeatedly with different numbers of rhipicephalus evertsi evertsi larvae. this resistance was associated with a drastic reduction in the number of ticks that attached but not in the ability to feed and moult by immatures already established on the hosts. furthermore, resistance reduced to below 50% the proportion of nymphs which emerged from the larvae applied to the three host g ...19883195049
on the critical transition temperature of unfed adult rhipicephalus evertsi evertsi and rhipicephalus eversti mimeticus (ixodoidea: ixodidae). 19883218395
arthropod parasites of common reedbuck, redunca arundinum, in natal.twenty-five common reedbuck, redunca arundinum, from the himeville region, 21 from the eastern shores nature reserve, 4 from the charter's creek nature reserve and 2 from the st lucia game park, natal were examined for arthropod parasites. the reedbuck from himeville were infested with 4 ixodid tick species, those from the eastern shores with 7 species and those from charter's creek and st lucia with 6 species. rhipicephalus evertsi evertsi was the only tick common to the 4 localities. the lice ...19883353095
the infection of various tick species with babesia bigemina, its transmission and identification.strains of boophilus decoloratus and b. microplus were easily infected with a single stock of babesia bigemina; boophilus annulatus could be infected less easily, and it was difficult to infect rhipicephalus evertsi. two strains of r. appendiculatus and one strain each of r. bursa and hyalomma anatolicum excavatum were refractory. the same stock of b. bigemina was transmitted by nymphs and adults of b. decoloratus but only by nymphs of r. evertsi. vertical infection was not observed in r. everts ...19883387405
kinetic properties of toxic protease inhibitors isolated from tick eggs.1. egg-toxins from rhipicephalus evertsi evertsi, boophilus microplus, boophilus decoloratus and hyalomma truncatum were found to be inhibitors of trypsin and in two cases also of chymotrypsin. 2. fast tight-binding and slow-binding inhibition were observed. 3. immunological identity of the toxins were assessed with ouchterlony immunodiffusion and elisa. 4. the protease content of b. decoloratus and amblyomma hebraeum tick eggs were determined by a linked enzyme assay. 5. the predictive value of ...19883391338
[interactions of temperature and relative humidity on the adult phase of rhipicephalus evertsi mimeticus off the host]. 19873434029
[interaction of temperature and relative humidity on preimaginal stages of rhipicephalus evertsi mimeticus off the host]. 19873439392
the transstadial transmission of babesia caballi by rhipicephalus evertsi evertsi.rhipicephalus evertsi evertsi larvae were fed on the ears of rabbits. seven days after larval infestation, unfed, newly moulted nymphae were manually removed to infest a splenectomized donkey showing a patent babesia caballi infection. engorged nymphae were collected from the donkey and the ensuing adult ticks were placed on a susceptible horse. the horse contracted a b. caballi infection showing a prepatent period of 19 days after tick infestation. a very low parasitaemia, (highest score 2), wh ...19873444624
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
histology and ultrastructure of the glands associated with the porose areas on the gnathosoma of rhipicephalus evertsi evertsi before and during oviposition.histological and electronmicroscopical studies have shown that the subcuticular tissue associated with the porose areas of female rhipicephalus evertsi evertsi consists of paired multicellular, alveolar and lobularly arranged glands. at least two types of cells are clearly distinguishable, according with their location. proximally, in direct association with the pores, cells with small and long nuclei are present. these cells are aligned along large, elongated lumina containing numerous microvil ...19873453789
[functional significance of the areae porosae of female rhipicephalus evertsi evertsi, neumann, 1897]. 19863536406
[the mechanics of oviposition in rhipicephalus evertsi evertsi neumann, 1897]. 19873593192
detection of immune response in rabbits infested with rhipicephalus appendiculatus and rhipicephalus evertsi evertsi.two groups of rabbits infested repeatedly with rhipicephalus evertsi evertsi and r appendiculatus acquired resistance as evidenced by reduced ectoparasite engorged weights and development of anti-tick antibodies in the hosts. the enzyme-linked immunosorbent assay (elisa) using salivary gland antigens of r appendiculatus was able to detect antibody responses to both the homologous and heterologous tick challenges. it was concluded that the immune response in hosts infested by these two tick speci ...19873685635
[the subspecific validity of rhipicephalus evertsi mimeticus donitz, 1910]. 19863705799
[development and reproduction of rhipicephalus evertsi mimeticus (donitz, 1910). 1. the biology of reproduction]. 19863727870
[development and reproduction of rhipicephalus evertsi mimeticus (donitz, 1910). 2. the biology of development]. 19863727871
changes in the protein pattern in the salivary glands of paralysis inducing female rhipicephalus evertsi evertsi during infestation. 19863751387
investigations into the localization of pheromone emission of male rhipicephalus evertsi evertsi during infestation. 19863751390
investigations into the function and chemical compositions of the porose areas secretion of rhipicephalus evertsi evertsi during oviposition.major differences were observed in hexane, ethanol and butanol extracts of eggs obtained from rhipicephalus evertsi evertsi females in which the porose areas functioned normally (ap+ eggs) and from r. evertsi evertsi in which the porose areas were selectively destroyed by electrocautery (ap- eggs). mass yields and uv spectra of the hexane extracts were similar for ap+ and ap- eggs. the uv spectra changed only slightly in the 294-320 nm range with respect to time and temperature. high performance ...19863763167
immunological responses and the role of the paralyzing toxin in rabbits infested with rhipicephalus evertsi evertsi.twenty-nine rabbits were exposed to 4 infestations with 20, 50, and 100 adult red-legged ticks (rhipicephalus evertsi evertsi). upon challenge, 16 rabbits (55%) contracted paralysis, and 14 of these (88%) died. most deaths occurred in rabbits challenged with 100 ticks. immunity to paralysis and subsequent resistance to tick feeding developed in the hosts that survived the initial challenge. antibody titers to a salivary gland antigen increased progressively as determined by the following tests: ...19863789273
isolation of a neurotoxin from the salivary glands of female rhipicephalus evertsi evertsi.a quantitative study of the changes in the protein pattern of the salivary glands of female rhipicephalus evertsi evertsi during the entire repletion process was undertaken. these results, in conjunction with the previously determined toxic phase, indicated the presence of a toxic protein. the development of a sensitive in vitro assay using a xenopus nerve-muscle preparation, made it possible to identify toxic phases during feeding and to assay fractions of salivary gland extracts during toxin i ...19863819963
studies on the ability of different strains or populations of female rhipicephalus evertsi evertsi (acarina:ixodidae) to produce paralysis in sheep.simultaneous infestation of 3-6 month-old black-head sheep with 15 south african wild strains of rhipicephalus evertsi evertsi males and females as well as a strain from rwanda clearly showed that all strains are capable of inducing paralysis. assessment of the infestation-rate of engorging female ticks during the period that their mass ranged between 15 and 21 mg/kg sheep body mass indicated that toxicity is quantitatively identical and exhibits no intraspecific gradations. the period between t ...19863960487
investigations into the paralysis-inducing ability of rhipicephalus evertsi mimeticus and that of hybrids between this subspecies and rhipicephalus evertsi evertsi.studies performed on sheep showed that rhipicephalus evertsi mimeticus is a paralysis-competent tick species whose toxicity is either the same as, or only slightly less than that of r.e. evertsi. it was also proved that the paresis or paralysis induced by the mimeticus females is characterized by a constant incubation period which is independent of the tick infestation rate and body mass of the host, and consequently of its age. this period is entirely determined by the state of repletion of the ...19863960488
investigation into the participation of male pheromones of rhipicephalus evertsi evertsi during was shown in this study that rhipicephalus evertsi evertsi males emit pheromones in the preparasitic as well as in the parasitic phases. conspecific unengorged male and female images exhibited a high response to water-soluble volatiles collected from unengorged males. a vigorous assembly of unfed female r. evertsi evertsi occurred on filter paper discs which had been in contact with either unfed or 5- and 9-day fed males. progressively increasing percentages of conspecific unengorged males re ...19854047618
the experimental transmission of theileria ovis by rhipicephalus evertsi mimeticus and r. bursa. 19724197846
observations on babesia equi in the salivary glands of rhipicephalus evertsi. 19734802548
[investigations on the influence of temperature and relative humidity on development and survival of rhipicephalus evertsi evertsi neumann, 1897 (author's transl)]. 19744833627
toxaphene-resistant ticks occurring on cattle in uganda: boophilus decolaratus, rhipicephalus evertsi and rhipicephalus appendiculatus. 19705526750
crimean-congo hemorrhagic fever in south africa.crimean-congo hemorrhagic fever virus was isolated for the first time in south africa in february 1981, from the blood of a 13-year-old boy who died in johannesburg after attending a camp in a nature reserve in the western transvaal. virus was isolated from 21/120 pools of questing ticks from the nature reserve, the infected species being hyalomma marginatum rufipes and h. truncatum. virus was also isolated from 4/38 pools of partially engorged ticks and other ectoparasites collected off hosts, ...19836418019
seasonal prevalence of ixodid ticks on cattle in the windhoek district of south west africa/namibia.the seasonal prevalence of ixodid ticks was determined over a 2-year period by the weekly removal from at least 5 cattle of all adult ticks and the immature stages of rhipicephalus evertsi mimeticus in the ears. the highest mean weekly burden was 286,6 adult ticks/cow/week in march 1979, and the lowest 6,9 adult ticks/cow/week in july 1979. virtually no tick control is practised in this area. rhipicephalus capensis group adults peaked in the summer from october to march/april. rhipicephalus ever ...19846533509
arthropod parasites of hartmann's mountain zebra, equus zebra hartmannae, in south west africa/namibia.twelve hartmann's mountain zebra, equus zebra hartmannae, were shot for arthropod parasite recovery during the period june 1980-june 1981 on a farm in the khomas hochland region of south west africa/namibia. four species of gasterophilus larvae, 1 species of rhinoestrus larvae and 3 ixodid tick species were recovered. the seasonal prevalence of the gasterophilus species larvae and of rhipicephalus evertsi mimeticus was determined. three horses examined on the same farm were infested with larvae ...19846533510
some helminth and arthropod parasites of the grey duiker, sylvicapra grimmia.sixteen grey duikers were culled on the farm riekert 's laager in the central transvaal at irregular intervals from may 1979-march 1981. one trematode species, 3 cestode species and 16 nematode species were recovered from these animals. of these the following are new helminth records for this antelope: cooperia hungi , cooperia neitzi , cooperia pectinata , trichostrongylus axei, trichostrongylus colubriformis, trichostrongylus falculatus , trichostrongylus instabilis , impalaia tuberculata , ne ...19836676685
[efficacy of the paraimmunity inducer pind-avi in rhipicephalus evertsi evertsi infestations in sheep: current perspectives in tick control and the prevention of tick paralysis]. 19846720165
[physiopathology of rhipicephalus evertsi evertsi neumann, 1897, induced tick paralysis of sheep]. 19836847597
karai virus, a probable arbovirus isolated from sheep and from the tick rhipicephalus evertsi in kenya. 19827068957
[sectional classification of the toxicity of the paralysis-inducing female rhipicephalus evertsi evertsi neumann, 1897, during repletion]. 19827090645
[antitoxic immunity in rhipicephalus evertsi evertsi-paralysis in sheep]. 19827090650
relationship between ticks and zebu cattle in southern uganda.tick populations were observed on zebu (bos indicus) cattle over a period of 2 years at entebbe, uganda where the climate was thought to be highly favourable for the free-living stages of ticks. collections of all instars of ticks were made from the body surfaces of the cattle at intervals of between 1 and 5 weeks. the species recorded in order of decreasing abundance were rhipicephalus appendiculatus, amblyomma variegatum, boophilus decoloratus, rhipicephalus evertsi evertsi, rhipicephalus simu ...19827101465
[action potentials and conduction velocities of the tibial nerve in sheep paralysis caused by rhipicephalus evertsi evertsi]. 19827113523
[sensitivity of laboratory animals to rhipicephalus evertsi evertsi paralysis]. 19827124196
parasites of domestic and wild animals in south africa. xv. the seasonal prevalence of ectoparasites on impala and cattle in the northern transvaal.the prevalence of ectoparasites on a total of 36 impala (aepyceros melampus) slaughtered monthly from february 1975 to february 1976 and a total of 24 cattle slaughtered monthly from march 1976 to march 1977 in the nylsvley provincial nature reserve was determined. six species of ixodid ticks were collected from the impala and these, in order of abundance, were: rhipicephalus evertsi evertsi, rhipicephalus appe. diculatus, amblyomma hebraeum, boophilus decoloratus, ixodes cavipalpus and hyalomma ...19827177586
[plasma lysozyme activity in tick paralysis of sheep caused by rhipicephalus evertsi evertsi]. 19827201794
[neurophysiopathology of rhipicephalus evertsi evertsi paralysis]. 19817282181
[histology of the foveal glands in rhipicephalus evertsi evertsi neumann, 1897]. 19817337651
cattle ticks from the waterberg district of the transvaal.macroscopically visible ticks were collected from the hides of 28 cattle slaughtered in pairs during a period of 14 months in the waterberg district. in order of prevalence rhipicephalus appendiculatus, rhipicephalus evertsi evertsi, amblyomma hebraeum, hyalomma marginatum rufipes, ixodes cavipalpus, hyalomma truncatum and boophilus decoloratus were recovered. immature stages of the three commonest species constituted a major portion of the population for varying periods during the months april ...19807452655
[toxic phase of the paralysis-inducing female rhipicephalus evertsi evertsi neumann, 1897, during repletion]. 19807456907
a shared epitope found in the major paralysis inducing tick species of africa.cross-reactivity between all the paralysis inducing tick species of veterinary relevance in africa was demonstrated, by using a monoclonal antibody directed against the paralysis inducing toxin of rhipicephalus evertsi evertsi. western blot results, together with amino acid composition studies indicated that this monoclonal antibody recognizes protein bands of similar molecular mass and amino acid composition in r. evertsi evertsi and ixodes rubicundus. this suggests that the karoo paralysis tox ...19947543039
the effect of host resistance on the metabolic rate of engorged females of rhipicephalus evertsi evertsi.this study investigated the effect of acquired resistance in guinea-pigs on the metabolic rate of adult females of the tick rhipicephalus evertsi evertsi. guinea-pigs were subjected to three successive infestations of ticks and the rate of co2 production (vco2) measured in first and third infestation engorged females. ticks which fed on resistant hosts showed a 52% decrease in mass compared to ticks that fed on naive animals. reduction in mass was accompanied by a decrease in vco2 (mlh-1) per ti ...19957548947
the effects of tick numbers and intervals between infestations on the resistance acquired by guinea-pigs to adults of rhipicephalus evertsi evertsi (acari: ixodidae).guinea-pigs were infested three times at short (1 week) intervals or long (10 week) intervals between successive infestations with low (1), medium (8) and high (15) numbers of adult rhipicephalus evertsi evertsi. to compare the resistance developed by the hosts at short and long intervals between infestations, a challenge (fourth) infestation was performed with the high number of ticks. resistance was assessed by comparing the mean weight of engorged female ticks that dropped from the hosts. con ...19947555412
the localization of a paralysis toxin in granules and nuclei of prefed female rhipicephalus evertsi evertsi tick salivary gland cells.a monoclonal antibody directed against a paralysis toxin of rhipicephalus evertsi evertsi ticks was used to localize the toxin in cytoplasmic granules and, surprisingly, chromatin of the nuclei of cells which resemble the "b" cell type in the salivary glands of rhipicephalus appendiculatus, boophilus microplus and ixodes holocyclus. the association of toxin with chromatin indicates that the toxin may have a regulatory function. evidence is provided to support the view that the toxin is made up o ...19937628232
investigations into lymphocyte transformation and histamine release by basophils in sheep repeatedly infested with rhipicephalus evertsi evertsi ticks.the immune response of a natural host of rhipicephalus evertsi evertsi to feeding by this tick species was investigated with respect to the effects of tick salivary gland extracts on the transformation of peripheral blood lymphocytes and the release of histamine by basophils obtained from repeatedly infested sheep. the results indicated that there was no stimulation of lymphocyte transformation but that histamine release was elevated 10 fold after four infestations. although this suggests a hype ...19937628233
[descriptive epidemiology of bovine theileriosis caused by theileria annulata in mauritania, subsaharian west africa].tropical bovine theileriosis due to theileria annulata has been discovered recently in mauritania. an epidemiological study performed in the dry season allowed to better determine the serological prevalence of t. annulata infection and its associated factors. the sex does not seem to have any influence, the role of the breed could not be clearly established, whereas, the age, the geographical origin and the management of the herd have a significant influence on the serological prevalence. these ...19947863061
parasites of domestic and wild animals in south africa. xxxii. ixodid ticks on scrub hares in the transvaal.a total of 264 scrub hares (lepus saxatilis) were examined for ixodid ticks at various localities in the kruger national park, eastern transvaal lowveld. thirteen tick species were recovered from these hares. the seasonal abundances of the immature stages of amblyomma hebraeum, amblyomma marmoreum, hyalomma truncatum, rhipicephalus appendiculatus, rhipicephalus evertsi evertsi, rhipicephalus simus and rhipicephalus zambeziensis and all stages of a rhipicephalus sp. (near r. pravus) were determin ...19937970571
[ticks and hemoparasitoses of livestock in senegal. vi. the soudano-sahelian zone].the authors report the results of a study on ticks and hemoparasitoses among cattle, sheep and goats in the sudano-sahelian zone. during a period of 15 months, ticks were systematically removed from 40 cattle, 40 sheep and 40 goats in order to assess the population dynamics and determine more accurately the preferential sites of settlement of the different species. the following species were collected in ruminants: hyalomma truncatum, h. marginatum rufipes, rhipicephalus evertsi evertsi, rh. gui ...19947991897
[crimean-congo hemorrhagic fever in senegal. latest data on the ecology of the cchf virus].the authors finalize the knowledge on the ecology of the cchf virus in senegal, west africa. they specify two new major data for the understanding of the viral ecology in west africa. the recognition of a bird species, common and widely distributed in senegal (tockus erythrorhynchus, coraciiformes, bucerotidae), that replicates the virus and infects the immature stages of its current parasite hyalomma marginatum rufipes in more than 90% of the cases, explains why the minimum infection rate of th ...19948003897
control of tsetse flies in uganda by dipping cattle in deltamethrin.the effect of treating cattle with deltamethrin to control tsetse flies and ticks was investigated on 2 ranches 8 km apart in central uganda where there is a high risk of trypanosomosis. this area had a moderate challenge of glossina pallidipes. the cattle had very low challenge of rhipicephalus appendiculatus, amblyomma variegatum, boophilus decolaratus and rhipicephalus evertsi evertsi, due to regular treatment with dioxathion. on one ranch a dip was charged with deltamethrin to treat cattle r ...19948009646
observations on cattle ticks in huila province (angola).in huila province of angola, 3864 ticks were collected during a parasitological survey carried out in the rainy season from october 1990 to april 1991. the samples were collected from cattle gathered for the annual vaccination campaign against contagious bovine pleuropneumonia, anthrax and blackleg in 18 veterinary stations of six municipalities. after tick classification, the following proportions of ticks were obtained: rhipicephalus evertsi mimeticus (27.1%), amblyomma pomposum (26.4%), booph ...19948171837
prevalence of rickettsia-like organisms and spotted fever group rickettsiae in ticks (acari: ixodidae) from zimbabwe.the prevalence of rickettsia-like organisms in ticks from zimbabwe was determined using the hemolymph test. amblyomma hebraeum had the highest prevalence of rickettsia-like organisms. other species with rickettsia-like organisms included amblyomma sparsum, amblyomma variegatum, hyalomma marginatum rufipes, ripicephalus simus, haemaphysalis leachi, amblyomma rhinocerotis, and hyalomma truncatum. ticks with no demonstrable rickettsia-like organisms infection were boophilus decoloratus, haemaphysal ...19958551500
comparison of resistance in three breeds of cattle against african ixodid ticks.tick resistance in three breeds of cattle, two indigenous breeds (arssi and boran) and one boran x friesian cross-bread, were compared following natural tick infestations at abernossa ranch in ethiopia. the local arssi breed was found to have the highest tick resistance, followed by the boran breed, whereas the boran x friesian was the least resistant. over a period of 12 months, from october 1991 to september 1992, a total of 32,897 ticks composed of four genera were collected from the animals. ...19968665816
efficacy of pheromone-acaricide-impregnated tail-tag decoys for controlling the bont tick, amblyomma hebraeum (acari: ixodidae), on cattle in zimbabwe.a large-scale field test using pheromone-acaricide-impregnated plastic tail-tag decoys demonstrated excellent efficacy of these devices for control of the bont tick, amblyomma hebraeum, on cattle in zimbabwe. the tail tags were impregnated with a mixture containing o-nitrophenol, methyl salicylate, 2,6-dichlorophenol and phenylacetaldehyde and one of three different acaricides (cyfluthrin, flumethrin or alphacypermethrin). o-nitrophenol and methyl salicylate are components of the a. hebraeum att ...19968746132
an assessment of host resistance to ticks on cross-bred cattle in burundi.groups of cattle of four different cross-breeds (ankole x friesian, ankole x brown-swiss, ankole x guernsey, ankole x sahiwal) plus a group of pure ankole cattle were immunized against tick-borne diseases: east coast fever, using a theileria parva trivalent vaccine, and anaplasmosis, babesiosis and, subsequently, heartwater. with the exception of two small subgroups of ankole and ankole x sahiwal which were treated by weekly spraying using delnav, all the groups were exposed to natural field cha ...19968834737
adult ixodid ticks on two cattle breeds in the south-western free state, and their seasonal dynamics.a study was conducted to compare the species of adult ixodid ticks on friesian and bonsmara cattle and their seasonal dynamics. between five and ten animals of each breed were kept on natural false upper karoo vegetation, typical of the south-western free state. between may 1990 and october 1991, the animals were examined once or twice a month for the presence of adult ticks which were removed, counted and identified. six species of ixodid ticks were recorded. the species composition on the two ...19968848299
detection of theileria annulata by the pcr in ticks (acari:ixodidae) collected from cattle in mauritania.we report on the detection of theileria annulata in infected hyalomma ticks by the pcr using primers derived from the gene encoding the 30 kda major merozoite surface antigen (tamsi-1). no inhibition of the pcr was observed and as little as 0.1 pg of parasite dna, corresponding to 12 sporozoites, could be detected in non-infected tick dna samples, spiked with t. annulata genomic dna. hyalomma dromedarii ticks, fed on a calf experimentally infected with t. annulata, were used to validate the pcr ...19979203350
a sero-epidemiological survey of equine piroplasmosis in the northern and eastern cape provinces of south africa.serum samples from yearling thoroughbred horses (n = 176) in the magisterial districts of colesberg, venterstad, and wodehouse in the northern and eastern cape provinces were collected between september and november 1995 to determine the prevalence of antibodies to babesia equi and babesia caballi in these regions. samples were examined for specific antibodies using the indirect fluorescent antibody test. the 95% confidence intervals for the prevalence of serum antibodies in the 3 districts comb ...19969284032
evidence to show that an agent that cross-reacts serologically with cowdria ruminantium in zimbabwe is transmitted by ticks.the serological diagnosis of heartwater based on reactions to the immunodominant cowdria ruminantium major antigen protein-1 (map-1) is impaired by the detection of false-positive reactions. in this study, the prevalence of false-positive reactions on seven heartwater-free farms in zimbabwe was determined to be 8-94% by immunoblotting against c. ruminantium antigens. the highest prevalence of false-positives on spring valley farm correlated with the presence of rhipicephalus evertsi evertsi tick ...19989493330
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