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1.
A serological survey of bovine babesiosis and anaplasmosis was conducted in the foot-and-mouth disease buffer zone surrounding the Kruger National Park in South Africa between 2001 and 2003 to determine whether the withdrawal of government-subsidized dipping in certain regions had affected the seroprevalence of these tick-borne diseases. Seroprevalence of Anaplasma marginale and Babesia bovis increased during the study period. This increase was greater in Limpopo Province where farmers had to supply their own acaricide than in Mpumalanga Province where dipping materials were provided by the local Veterinary Services. The number of animals testing positive for B. bigemina decreased in both provinces during the study period, which was attributed to possible vector displacement rather than more effective tick control measures. Responses to a questionnaire on ticks and tick-borne diseases revealed local knowledge on the subject to be highly variable and sometimes incorrect.  相似文献   

2.
A molecular epidemiology investigation was undertaken in two Nigerian states (Plateau and Nassarawa) to determine the prevalence of pathogens of veterinary and public health importance associated with ticks collected from cattle and dogs using PCR, cloning and sequencing or reverse line blot techniques. A total of 218 tick samples, Amblyomma variegatum (N=153), Rhipicephalus (Boophilus) decoloratus (N=45), and Rhipicephalus sanguineus (N=20) were sampled. Pathogens identified in ticks included piroplasmids (Babesia spp., Babesia bigemina and Babesia divergens), Anaplasma marginale and Rickettsia africae. Piroplasmids were identified in A. variegatum, A. marginale was found in R. decoloratus, while R. africae was detected in all tick species examined. Ehrlichia spp. and Theileria spp. were not identified in any of the ticks examined. Of the 218 ticks examined, 33 (15.1%) contained pathogen DNA, with the presence of B. divergens and R. africae that are zoonotic pathogens of public health and veterinary importance. The variety of tick-borne pathogens identified in this study suggests a risk for the emergence of tick-borne diseases in domestic animals and humans, especially amongst the Fulani pastoralists in Plateau and Nassarawa states of Nigeria.  相似文献   

3.
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 encountered on the cattle, but few cattle carried ticks of any species (only 13 and 4.6% of tick counts of the cattle yielded adult R. appendiculatus and Boophilus spp., respectively). Animals were more likely to carry one or more adult Boophilus spp. ticks if they also carried one or more R. appendiculatus adults (OR=14.4, CI=9.2, 22.5). The use of pour-on acaricides was associated with lower odds that animals carried a R. appendiculatus tick (OR=0.29, CI=0.18, 0.49) but higher odds that they carried a Boophilus spp. tick (OR=2.48, CI=1.55, 3.97). Animals >4 months old and those with a recent history of grazing had higher odds of carrying either a R. appendiculatus (ORs=3.41 and 2.58, CIs=2.34, 4.98 and 1.80, 3.71), or a Boophilus spp. tick (ORs=5.70 and 2.18, CIs=2.34, 4.98 and 1.49. 3.25), but zero-grazing management did not prevent ticks attaching to cattle even when combined with high-frequency acaricide treatments. The odds that animals carried ticks varied amongst the agro-ecological zones (AEZs) and administrative districts where the farms were situated-but there was still considerable residual variation in tick infestation at the farm level.  相似文献   

4.
The study was conducted in a peri-urban agricultural system at Botshabelo, a city in the south-eastern Free State. A questionnaire survey revealed that 88.5% of cattle farmers in the area experienced problems related to ticks and tick-borne diseases. Because of the cost of commercial acaricides the Botshabelo farmers use alternative, cheaper methods of tick control, including the application of used engine oil. The specific aim of the study was to determine whether used engine oil can effectively control ticks on cattle. From March to August 1996 the tick burdens of ten control animals and six animals treated by their owner with used engine oil were compared. The total tick burdens for the 6 month period differed significantly between the two experimental groups. The efficacy of the used engine oil on the treated group varied between 15.1% and 64.8% with a mean of 38.1%. Although commercial acaricides can be more cost-effective, the application of used engine oil can be useful to reduce tick numbers on cattle during periods of peak abundance. Another advantage in that the use of the oil will not influence existing endemic stability of Anaplasma marginale and Babesia bigemina infections because of the residual tick burdens after treatment.  相似文献   

5.
A serological survey of bovine babesiosis and anaplasmosis in communal cattle was conducted in the northwestern province of Tete, Mozambique. Blood was collected from cattle ranging from 4 to 15 months old from randomly selected farms from six districts. Thirty-nine per cent of all 478 calves tested in Tete Province were seropositive to the ELISA for Babesia bovis antibodies and 63% of all calves were seropositive in the card agglutination test for Anaplasma marginale. Seroprevalence of B. bovis ranged from 22.8% in Tete City District to 48.1% in Angonia District. For A. marginale, it ranged from 34.4% in Angonia District to 87.3% in Moatize District. The dominant factor affecting seroprevalence for both haemoparasites was district and there was a trend for higher intensity of tick control to be associated with a higher seroprevalence of B. bovis and a lower seroprevalence of A. marginale. The obvious differences were the low prevalence of B. bovis in Tete City Council District and the low prevalence of A. marginale in Angonia District. The levels of exposure to B. bovis seen in our study are well below any that could be considered to be consistent with endemic stability, yet they are sufficiently high to ensure that clinical disease would be a risk. The seroprevalence of A. marginale, however, suggests that endemic stability with respect to this disease could exist in districts other than Angonia. There was no strong and consistent relationship between the intensity of control and the likelihood of seropositivity to either of the diseases.  相似文献   

6.
Tick-borne diseases are of increasing concern in many countries, particularly as a consequence of changes in land use and climate. Ticks are vectors of numerous pathogens (viruses, bacteria, protozoa) that can be harmful to humans and animals. In the context of animal health, bovine babesiosis poses a recurrent threat to cattle herds. In this study, we use a modeling approach to investigate the spread of babesiosis and evaluate control measures. A previously developed tick population dynamics model (here, Ixodes ricinus) is coupled with a pathogen spread model (here, the protozoan Babesia divergens), which describes pathogen spread in a dairy herd through the following processes: transmission, acquisition, transovarial transmission, transstadial persistence, and clearance of the pathogen. An assessment of the simulated B. divergens prevalence levels in ticks and cattle in the context of existing knowledge and data suggested that the model provides a realistic representation of pathogen spread. The model was then used to evaluate the influence of host density and the effect of acaricides on B. divergens prevalence in cattle. Increasing deer density results in an increase in prevalence in cattle whereas increasing cattle stocking rate results in a slight decrease. A potential increase in deer density would thus have an amplification effect on disease spread due to the increase in the number of infected ticks. Regular use of acaricides produces a reduction in pathogen prevalence in cattle. This model could be adapted to other tick-borne diseases.  相似文献   

7.
Blood samples and ticks were collected from 48 cattle and 74 horses from seven sites in the Peten region of Guatemala. Data on body condition, mucous membrane capillary refill time and tick infestation levels were recorded for each animal in the study. Horses had significantly higher levels of tick infestation than cattle, as well as poorer body condition scores. Seroprevalence of Babesia spp. was 95.8% for B. bovis in cattle, 89.6% for B. bigemina in cattle, and 92.7% for B. equi in horses. Seroprevalence of Anaplasma marginale in cattle was 87.5%, similar to reports in animals from other regions of Central America. This is the first time that A. phagocytophilum has been reported in animals from this region, with overall PCR-prevalence of 27.6% in cattle and horses, and seroprevalence of 28.4% (52% in cattle and 13% in horses). An agent was identified with serological cross-reactivity and close genetic relatedness to Ehrlichia ruminantium, but further testing confirmed that the agent in Guatemalan cows was not the agent of heartwater. Ticks were identified to species with the predominant species identified on cattle as Boophilus microplus and Amblyomma cajennense, while Anocentor nitens and A. cajennense were most commonly found on horses. Prevalence of infection, tick infestation levels, host factors and environmental data were analyzed for association; A. nitens was significantly associated with A. phagocytophilum prevalence by village.  相似文献   

8.
Variations in the seroprevalence of antibody to Babesia bigemina infection by farm and animal level risk factors were investigated for 2 contrasting regions of Tanga and Iringa in Tanzania. Tanga is situated in the eastern part of the country and has typical tropical coast climate while Iringa is situated in the Southern Highlands and has a tropical highland climate. Two hundred farms from each region were selected using simple random sampling procedure and visited once between January 1999 and April 1999. Blood samples were collected from 1329 smallholder dairy animals on selected farms for harvesting serum which was subsequently used for serodiagnosis of B. bigemina using an indirect enzyme linked immuno-sorbent assay (ELISA). Of the 1329 sera samples screened, 34.9 % were positive for B. bigemina. The prevalence was higher in Iringa Region [43%, 95% confidence intervals (CI) = 39.5-47.3] than in Tanga Region (27%, CI = 23.6-30.5). Using a logistic binomial regression model as an analytical method for predicting the likelihood of animal seropositivity, we found (in both regions) that the risk of positive reaction varied with the animal's age, history of grazing and geographical location. Seroprevalence increased with age (beta = 0.01 and 0.01 per year of age, P < 0.005 in Tanga and Iringa, respectively). Animals located in Lushoto and Iringa urban district were associated with increased risk of seropositivity [Odds ratio (OR) = 4.24, P = 0.001, for Lushoto, and OR = 1.81, P = 0.040, for Iringa Urban, respectively). Animals grazed 3 months prior to sampling had higher odds for seropositivity than zero/semi-grazed, despite farmer-reported high frequency of tick control (OR = 2.71, P = 0.0087, for Tanga, and OR = 4.53, P = 0.001, for Iringa). Our study suggests that even though herd sizes are small, B. bigemina infection is widespread in many smallholder dairy farms and endemic stability with respect to this disease has not yet been attained, but the observed levels are sufficiently high to ensure that clinical disease would be a risk.  相似文献   

9.
A cell culture system for the tick-borne rickettsia Anaplasma marginale offers new opportunities for research on this economically important pathogen of cattle. A. marginale multiplies in membrane-bound inclusions in host cells. Whereas erythrocytes appear to be the only site of infection in cattle, A. marginale undergoes a complex developmental cycle in ticks and transmission occurs via the salivary glands during feeding. We recently developed a cell culture system for A. marginale using a cell line derived from embryos of Ixodes scapularis. Here we review the use of this cell culture system for studying the interaction of A. marginale with tick cells. Several assays were developed using the A. marginale/tick cell system. An adhesion assay was developed for the identification of proteins required by A. marginale for adhesion to tick cells. The effect of antibodies against selected major surface proteins in inhibiting A. marginale infection was tested in an assay that allowed further confirmation of the role of surface proteins in the infection of tick cells. A drug screening assay for A. marginale was developed and provides a method of initial drug selection without the use of cattle. The culture system was used to test for enhancing effects of tick saliva and saliva components on A. marginale infection. The tick cell culture system has proved to be a good model for studying A. marginale-tick interactions. Information gained from these studies may be applicable to other closely related tick-borne pathogens that have been propagated in the same tick cell line.  相似文献   

10.
OBJECTIVES: To compare the features of farms on which the exposure of young cattle to tick fever organisms is sufficient to ensure that immunity is high and the risk of clinical disease is low (endemic stability) with those of farms on which exposure is insufficient to induce widespread immunity (hence without endemic stability); to examine the relationships between the management of ticks and tick fever, and endemic stability to Babesia bovis, B. bigemina and Anaplasma marginale. DESIGN: Cross-sectional study of 874 cattle between the ages of 6 and 15 months on 64 dairy farms, from three centres in south-eastern Queensland (Mutdapilly, Dayboro and Kenilworth) and one centre in far-north Queensland (Malanda). PROCEDURE: Blood samples collected from between 5 and 20 calves from each farm were submitted for serological assay to determine exposure to B. bovis, B. bigemina and A. marginale. A questionnaire about the farm characteristics and the management of ticks and tick fever was completed with each farmer. RESULTS: On 73% of farms, confirmed clinical cases of tick fever were recalled by the farmer, indicating that tick fever was a threat on most farms. The majority of herds in the study (54 of 64) did not have sufficient numbers of seropositive animals aged between 6 and 15 months to have a low risk of tick fever. Region had an effect on the likelihood of endemic stability for all tick fever organisms. Cattle near Malanda in Far-north Queensland were more likely to be seropositive to B. bovis and B. bigemina. The method, strategy and intensity of tick control were not related to the likelihood of endemic stability when the effect of region was considered. The decision to leave a few ticks on cattle in an effort to induce endemic stability did increase the likelihood of endemic stability to A. marginale. However, in practical terms, it was ineffective, because only 26% of these farms had endemic stability against all three organisms. CONCLUSIONS: Given the low proportion of farms that have endemic stability to the tick fever organisms and the high likelihood of clinical disease, vaccination is recommended to protect dairy cattle from tick fever throughout the tick infested area of Queensland. However, further work is required to determine the economic value of vaccination, taking into account the costs of vaccination, of outbreaks and the protective value of vaccination.  相似文献   

11.
As part of a series of studies associated with the development of improved vaccines for heartwater (a tick-borne disease of ruminant livestock caused by Cowdria ruminantium), field surveys were carried out to assess losses associated with the disease and the costs associated with controlling it in the two main agro-ecological zones of Zimbabwe (lowveld and highveld) where heartwater is believed to be endemic and epidemic, respectively. In each zone, a cross-sectional study was performed in the main farming systems (smallholder (SH) and large-scale commercial (LSC) beef and dairy), followed by longitudinal studies in the same sectors to improve data accuracy for some parameters. Suspected heartwater-specific mortality in cattle was similar in all LSC sectors (p = 0.72) accounting for a median 1% mortality risk. Heartwater-specific mortality in SH areas was not assessed due to poor diagnostic ability of the farmers. Few LSC farms and SH households kept sheep; suspected heartwater-specific mortality in LSC sheep was 0.8% in the lowveld and 2.4% in the highveld. Goats were a major enterprise in SH areas but not on LSC farms. Suspected heartwater mortality in LSC goats was 0.8% at one site in the highveld and 17.5% on a farm in the lowveld. Application of acaricides was the major control method for heartwater and other tick-borne diseases on both SH and LSC farms. On LSC farms, plunge dipping was used most frequently and the number of acaricide applications ranged widely between 3 and 52 per year. The total cost of acaricides per head per annum was higher in highveld dairies than in highveld and lowveld beef enterprises (p = 0.03). In SH areas, cattle plunge dipping was conducted by the government with an average frequency of 8 +/- 2 (sd) immersions per annum in both the lowveld and highveld. The type of tick control on sheep and goats in all production systems was highly variable (ranging from none to hand removal or intensive acaricide treatment). Suspected heartwater cases on LSC farms were treated with tetracyclines; treatment was not reported in SH areas. Reported treatment costs were high (median Z$ 120) and highly variable (range Z$-833). Vaccination against heartwater with the live, blood-based vaccine was reported on only one LSC farm. LSC farms applying acaricide 30 or more times per year reported higher morbidity (p < 0.0001) and mortality (p < 0.0001) than farms applying acaricides less than 30 times a year. This finding supports the use of reduced tick control in the management of heartwater in Zimbabwe.  相似文献   

12.
用病原检查法对甘肃省４２个县市的１３１１头牛进行了牛蜱传性血液原虫病的大面积调查,证实该省牛蜱传染性血液原虫的种类为双芽巴贝斯虫,大巴贝斯虫,瑟氏泰勒虫,环形泰勒虫及国边虫等５种病原,  相似文献   

13.
A cross-sectional study was done of seroprevalence of Babesia bigemina, B.bovis, and Anaplasma marginale in cattle from eastern Bolivia, to characterise the risk of tick-borne disease in three ecological zones. Nineteen farms were sampled in the subtropical humid zone, 13 in the dry subtropical zone and nine in the lower western valleys of the Andean massif. The enzyme-linked immunosorbent assay was used. All three pathogens were widespread. For B. bovis, seroprevalences were high (75-78%) in the two subtropical zones which thus had low risk of disease from this infection; but the western valleys were endemically unstable with higher risk. For B. bigemina, seroprevalences were lower (24-57%) in the two subtropical zones and thus these areas were endemically unstable for disease from this infection. However, the seroprevalence of B. bigemina in the western valleys was too low (13%) for risk of disease in susceptible cattle to be considered high. For A. marginale, the seroprevalences in the two subtropical zones were low (19-32%) and very low (6%) in the western valleys suggesting all these zones were endemically unstable for anaplasmosis. Data for individual farms were analysed for risk of both forms of babesiosis; this showed low risk of disease in the subtropical humid zone, higher risk in the dry subtropical zone and variable risk in the western valleys.  相似文献   

14.
A 12-month study was conducted in 4 communal grazing areas in the Bushbuckridge region, Limpopo Province, South Africa. The main objective was to investigate the impact of reduced acaricide application on endemic stability to bovine babesiosis (Babesia bigemina and Babesia bovis) and anaplasmosis (Anaplasma marginale) in the local cattle population. To this end 60 cattle in each communal grazing area were bled at the beginning and the conclusion of the experimental period and their sera were assayed for B. bovis, B. bigemina and Anaplasma antibodies. Cattle in the intensively dipped group were dipped 26 times and maintained on a 14-day dipping interval throughout the study, whereas cattle in the strategically dipped group were dipped only 13 times. Three cattle, from which adult ticks were collected, were selected from each village, while immature ticks were collected by drag-sampling the surrounding vegetation. During the dipping process, a questionnaire aimed at assessing the prevalence of clinical cases of tick-borne disease, abscesses and mortalities was completed by an Animal Health Technician at each diptank. An increase in seroprevalence to B. bovis and B. bigemina and a decrease in seroprevalence to Anaplasma was detected in the strategically dipped group while in the intensively dipped group the converse was true. Amblyomma hebraeum was the most numerous tick species on the cattle, and Rhipicephalus (Boophilus) microplus was more plentiful than Rhipicephalus (Boophilus) decoloratus. Drag samples yielded more immature stages of A. hebraeum than of Rhipicephalus (Boophilus) spp. The incidence of clinical cases of tick-borne disease and of abscesses increased in the strategically dipped group at the start of the survey.  相似文献   

15.
The seroprevalence of Babesia bigemina and Babesia bovis antibodies in non-vaccinated cattle was monitored on a South African ranch. The main objective was to assess the endemic stability to bovine babesiosis in cattle maintained under relaxed tick-control measures. Cattle were bled at the age of 7, 8, 10, 17, 20 and 30-120 months and the sera tested for the presence of antibodies using the indirect fluorescent antibody (IFA) test. None of the animals were positive to B. bovis. Seroprevalence of B. bigemina antibodies was 46, 70, 90, 92, 54 and 82% in the various age classes, respectively. Endemic stability was therefore reached by the time the calves were 9 months old. The high seroprevalence of B. bigemina was probably due to the high vector tick population on the ranch, which would have encouraged frequent transmission of B. bigemina. An endemically stable situation to B. bigemina could therefore be achieved merely by adopting a tick-control method that allows a reasonable number of ticks on cattle rather than relying entirely on intensive tick control and vaccination.  相似文献   

16.
A cross-sectional study was carried out from July to September 1989 in Kaloleni Division, Coast Province, Kenya to estimate the prevalence of vector-transmitted diseases in small-holder dairy cattle and to identify the risk factors associated with different management systems. One hundred and thirty of the 157 herds with dairy cattle in Kaloleni Division were surveyed. These were from three agro-ecological zones (coconut-cassava, cashew nut-cassava and livestock-millet), comprised two management systems (stall-feeding and herded grazing) and were herds with either dairy cattle only or with Zebu and dairy cattle. A formal questionnaire sought answers to questions on cattle health and management practices. A total of 734 dairy and 205 Zebu cattle in 78 dairy and 52 mixed (dairy and Zebu) herds were sampled and screened for haemoparasites (Trypanosoma, Anaplasma, Babesia, and Theileria infections). Sera were tested for antibodies to Theileria parva, using the schizonts-antigen indirect fluorescent-antibody (IFA) test and to antibodies for Babesia bigemina and antigens to Anaplasma marginale by enzyme-linked immunosorbent assay (ELISA). Packed-cell volume (PCV) also was measured. Tick-control measures were practised by all except three of the farmers. Despite this, overall seroprevalence to T. parva was >70%--suggesting either that control practices were not strictly implemented or they were ineffective. The seroprevalence of T. parva in adult cattle kept in stall-feeding systems in the coconut-cassava zone was significantly lower (57+/-8% (S.E.)) than in herded-grazing systems (79+/-3%) and there was no association between antibody prevalence and age of cattle in this zone. Antibody prevalences in cattle in the cashew nut-cassava and the drier livestock-millet zone increased with age. Cattle in herded-grazing systems had an overall lower seroprevalence of T. parva infection in the livestock-millet zone (45+/-6%) than in the other two zones.Analysis was confined to the coconut-cassava zone for B. bigemina and to the coconut-cassava and cashew nut-cassava zones for A. marginale. Mean prevalences of B. bigemina were 40.9+/-9 and 73+/-6% for dairy cattle under stall-feeding and herded-grazing systems, respectively, and increased with age. Antigen prevalences of A. marginale were over 80% in all age groups of cattle in the coconut-cassava and cashew nut-cassava zones. Overall trypanosome prevalence in cattle was <1%. Trypanocidal treatment was uncommon. The variations in antibody prevalence associated with risk factors such as feeding system, agro-ecological zone and age of animal suggest that management system influenced exposure to tick-borne infection (particularly, T. parva infections) in small-holder dairy cattle in coastal Kenya.  相似文献   

17.
A longitudinal study was conducted in Southeast Uganda for 14 months on 640 Zebu cattle kept under natural tick challenge, with a view to identifying clinical features for prediction of seroconversion to Anaplasma marginale, Babesia bigemina and Theileria parva infections. Physical examination, condition scoring and tick counts were undertaken on all cattle every 4 weeks. In addition, 5300 sera were collected and analysed for antibodies against A. marginale, B. bigemina and T. parva infections using the enzyme-linked immunosorbent assay (ELISA). The major clinical features compiled included weight loss, fever (rectal temperature), anaemia (packed cell volume), pallor of mucous membranes, lymph node enlargement, staring coat, diarrhoea and lacrymation. The risk factors included tick challenge at village level, sex, age, Rhipicephalus spp. density and Boophilus spp. density on individual animals. Using a binary logistic regression model, the clinical features and risk factors were analysed. The results suggest that increasing rectal temperature was associated with increased probability for seroconversion to A. marginale, while high level of Rhipicephalus spp. density and increasing packed cell volume (PCV) were significantly associated with reduced probability of seroconversion. Although statistically significant, none of the factors had large effects, with odds ratios (OR) of 0.87, 1.15 and 0.98 for Rhipicephalus spp. density, rectal temperature and PCV, respectively. For B. bigemina infection, a high level of Boophilus spp. density, anaemia and staring coat were significantly associated with increased probability of seroconversion (OR 1.50, 1.78, 1.37, respectively). Presence of lacrymation and old age were associated with reduced probability of seroconversion (OR 0.52, 0.86 respectively). For T. parva infection, lymph node enlargement (OR 1.30) was associated with increased probability of seroconversion, while high Rhipicephalus spp. density and increasing packed cell volume (PCV) were associated with reduced probability of seroconversion (OR 0.68 and 0.98, respectively). In conclusion, presence and intensity of the respective tick vectors for tick-borne diseases, age and clinical features such as anaemia, fever, staring coat, lymph node enlargement and lacrymation are indicators for seroconversion to A. marginale, B. bigemina and T. parva infections in cattle. These indicators for seroconversion could be exploited in the development of decision support tools for clinical diagnosis of tick-borne diseases.  相似文献   

18.
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19.
The importance of equine piroplasmosis control in endemic countries has increased in recent years and plays an important role to maintain the international market open to the horse industry. The purpose of this study was to demonstrate the occurrence of equine piroplasmosis (Babesia equi or Theileria equi and Babesia caballi) in Brazil--a country where the disease occurs endemically--in different climatic conditions, and to evaluate the results of a strategy for tick control in order to decrease infection rates. Blood samples were taken from 720 horses on 28 farms from different regions and subjected for complement fixation testing. The strategy was based on the control of the tick population by spraying the horses with acaricides, treating positive horses and preventing cattle and horses from grazing together. A significant association was found in the prevalence of antibody titres in tropical and subtropical areas. A significantly lower prevalence rate occurred on those farms where measures to control tick population were established. Farms in endemic countries may significantly reduce the prevalence of equine piroplasmosis by establishing measures to control the tick population and treating chronic carrier horses. Additional measures for controlling ticks in tropical areas are also discussed.  相似文献   

20.
Bovine anaplasmosis is a tick-borne hemolytic disease of cattle that occurs worldwide caused by the intraerythrocytic rickettsiae Anaplasma marginale. Control measures, including use of acaricides, administration of antibiotics and vaccines, have varied with geographic location. Our research is focused on the tick-pathogen interface for development of new vaccine strategies with the goal of reducing anaplasmosis, tick infestations and the vectorial capacity of ticks. Toward this approach, we have targeted (1) development of an A. marginale cell culture system to provide a non-bovine antigen source, (2) characterization of an A. marginale adhesion protein, and (3) identification of key tick protective antigens for reduction of tick infestations. A cell culture system for propagation of A. marginale was developed and provided a non-bovine source of A. marginale vaccine antigen. The A. marginale adhesion protein, MSP1a, was characterized and use of recombinant MSP1a in vaccine formulations reduced clinical anaplasmosis and infection levels in ticks that acquired infection on immunized cattle. Most recently, we identified a tick-protective antigen, subolesin, that reduced tick infestations, as well as the vectorial capacity of ticks for acquisition and transmission of A marginale. This integrated approach to vaccine development shows promise for developing new strategies for control of bovine anaplasmosis.  相似文献   

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