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1.
Problems with the interpretation of epidemiological data in heartwater: a study on 23 farms 总被引：1，自引：0，他引：1
In an epidemiological study undertaken on 23 farms where heartwater occurs endemically, it was found that on an overall average, antibodies to Cowdria ruminantium were detected in 64.3% of the cattle, 6 adult Amblyomma hebraeum ticks were counted per animal and 7.0% of ticks were infected with the heartwater agent. It was found that the seropositivity of the animals was determined largely by the tick loads to which they were subjected and that the influence of the tick C. ruminantium infection rate was less evident. There was no parallel between the prevalence of heartwater on the farms and the immune status of the animals. In general, higher tick counts were recorded in herds where strategic tick control is practised than on farms with a total tick control programme. The method of tick control did not, however, appear to influence the immune status of the cattle, the tick infection rate, or the prevalence of heartwater. 相似文献
2.
Objective To determine practices for the control of cattle ticks on dairy farms in Queensland, the attitudes of farmers to tick infestations and to identify opportunities for and barriers against the introduction of non-chemical methods of tick control.
Design A survey of 199 dairy farmers from tick-infested parts of Queensland was undertaken by 20 dairy advisers and stock inspectors from October 1996 to June 1997. The sample was a proportional, random selection of dairy farms from four regions. A personal interview was conducted with each farmer and answers to 134 questions were obtained.
Results and conclusions Most farmers were not concerned by cattle ticks on their own farms, although they believed that ticks are important to the dairy industry. They were most concerned about the development of chemical resistance by cattle ticks. Inadequate facilities and lack of motivation appeared to be the factors most limiting to improving the methods of control. Most farmers claimed to have only small numbers of ticks at worst. Although a control program recom mended by the Queensland Dairyfarmers' Organisation was well regarded by farmers, few had adopted it. Many farmers saw no need to implement a strategic control program. 相似文献
Design A survey of 199 dairy farmers from tick-infested parts of Queensland was undertaken by 20 dairy advisers and stock inspectors from October 1996 to June 1997. The sample was a proportional, random selection of dairy farms from four regions. A personal interview was conducted with each farmer and answers to 134 questions were obtained.
Results and conclusions Most farmers were not concerned by cattle ticks on their own farms, although they believed that ticks are important to the dairy industry. They were most concerned about the development of chemical resistance by cattle ticks. Inadequate facilities and lack of motivation appeared to be the factors most limiting to improving the methods of control. Most farmers claimed to have only small numbers of ticks at worst. Although a control program recom mended by the Queensland Dairyfarmers' Organisation was well regarded by farmers, few had adopted it. Many farmers saw no need to implement a strategic control program. 相似文献
3.
Current small stock tick control practices and producer attitudes towards tick control in the eastern Cape Province of South Africa are discussed. These were ascertained from returns to a questionnaire survey to which 31.2% of farmers polled, responded. In general, producers did not favour an intensive tick control policy for small stock. Angora, mutton and wool farmers had a definite preference for synthetic pyrethroid acaricides, the majority treating either less than 6 times p.a. or between 11-15 times p.a. Most producers changed acaricides because of price. All small stock producers favoured plunge dip application of acaricides while the majority of wool sheep and Angora producers utilized footbath application as a second preference. Mutton producers favoured pour-on and hand spray application as a second choice. Producers who used plunge dip application techniques experienced the highest percentage of confirmed acaricide resistance which is in accordance with application preference. The general incidence of confirmed acaricide resistance, however, was of a low order but highest amongst mutton farmers. An average cost for acaricide treatment of R1.65 per small stock unit p.a. was calculated from data gained in this survey. Only a small number of producers used the available heartwater vaccine. Small stock mortalities experienced by producers per production unit indicated higher mortalities at high acaricidal treatment frequencies. Farmers allowing a small number of ticks to infest their sheep experienced fewer mortalities due to heartwater than those than kept their sheep free of ticks. Angora goat farmers experienced the same, but with higher mortalities, probably due to the apparently high susceptibility of Angora goats to heartwater. 相似文献
4.
The immunization of calves against heartwater: subsequent immunity both in the absence and presence of natural tick challenge 总被引：1，自引：0，他引：1
J L Du Plessis J D Bezuidenhout C J Lüdemann 《The Onderstepoort journal of veterinary research》1984,51(3):193-196
Cattle, vaccinated as calves with Cowdria ruminantium-infected tick stabilate, were challenged 6, 12 and 24 months later. In the absence of tick challenge, vaccination of calves induced a partial immunity against subsequent challenge at 12 and 24 months. In animals exposed to ticks, the resistance was no better than that of control, unvaccinated cattle. When they were challenged at 6 months of age there was no difference between vaccinated and unvaccinated calves, either in the absence or presence of tick challenge, and all the animals manifested a high degree of natural resistance. This study therefore suggests that the value of vaccinating Afrikander-cross calves in heartwater endemic areas should be further investigated. The indirect fluorescent antibody (IFA) test proved to be a valuable means of monitoring the serological response of vaccinated animals and detecting the sero-conversion of animals exposed to tick infection. On one hand, there was good correlation between the febrile reaction and the results of the IFA test on the sera of vaccinated and control cattle challenged with the heartwater agent, in that all sero-positive animals were resistant to challenge. On the other hand, though, a considerable percentage of the animals that were serologically negative were also resistant to challenge. 相似文献
5.
B C Simpson M S Lindsay J R Morris F S Muirhead A Pollock S G Prichard H G Stanley G R Thirlwell A G Hunter J Bradley 《The Veterinary record》1987,120(6):135-138
Five groups of Tswana-cross castrated male cattle between 20 and 30 months of age (a total of 158 animals) were transported from a ranch in a heartwater-free area of south Botswana to a feedlot near Gaborone in the east of Botswana where heartwater is endemic. On arrival, one group was vaccinated intravenously with the Onderstepoort sheep blood heartwater vaccine, one group was vaccinated intravenously with the new Onderstepoort tick-derived heartwater vaccine and a third group was vaccinated subcutaneously with this tick-derived vaccine. Vaccine reactions were blocked with long acting oxytetracycline on the first day of fever. A fourth group had a series of injections of long acting oxytetracycline on days 0, 7, 14 and 21 after arrival, and a fifth served as untreated controls. The animals remained at the feedlot for 65 days during which time they faced a low level of challenge by Amblyomma hebraeum ticks. None contracted heartwater and so they were then challenged, together with a further group of control cattle, with a dose of the sheep blood vaccine. Some animals in all groups had severe heartwater reactions and died despite therapy, but 76.7 per cent, 64.5 per cent and 74.3 per cent of the cattle in the blood vaccine, intravenous tick vaccine and long acting oxytetracycline groups respectively were resistant to challenge, compared with 48.3 per cent of the subcutaneous tick vaccine group and 36.4 per cent of the controls. It was concluded that intravenous vaccination of susceptible adult cattle with either the blood or the tick-derived vaccine needs careful monitoring in the month after vaccination and does not necessarily result in immune animals.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
6.
Yonow T Brewster CC Allen JC Meltzer MI 《The Onderstepoort journal of veterinary research》1998,65(4):263-273
We present a simple model of the dynamics of heartwater that we use to explore and better understand various aspects of this disease. We adapted the Ross-Macdonald model for malaria epidemiology so that we could consider both host and vector populations, and evaluate the interactions between the two. We then use two more biologically detailed models to examine heartwater epidemiology. The first includes a carrier state and host mortality, and the second includes density dependence. The results from all three models indicate that a stable equilibrium with high disease levels is probably the standard situation for heartwater (R0 between 5.7 and 22.4). More than 80% of cattle become infected with heartwater if only 12% of infected tick bites produce an infection in cattle, if tick burdens are as low as only five ticks per host per day, or if tick lifespans are as short as 7 d. A host recovery rate of 30 d results in over 50% of the cattle becoming infected with heartwater. Our analyses indicate that it is quite difficult to prevent the establishment and maintenance of high levels of heartwater in a herd, thereby supporting previous suggestions that any attempts at controlling this disease through stringent tick control regimens are not warranted. 相似文献
7.
The seasonal pattern of tick load on Bunaji cattle under traditional management in northern Nigeria was observed over 12 months to investigate the possibilities of strategic use of acaricide. Ticks were removed 2-3 times weekly by hand from 16 animals, counted and the species determined. Tick load was low in the dry season (2-5 ticks per animal per week), increased after the onset of the first scattered rains, reached a peak (40 ticks per animal per week) 1 month after the beginning of the heavy rains, and declined thereafter. The dominant tick species was Amblyomma variegatum; other species found were Boophilus spp., Rhipicephalus spp. and Hyalomma spp. The low level of tick load compared with data from literature and from crossbred (Friesian-Bunaji) cattle kept in the study area suggests high tick resistance in Bunaji cattle. A biologically feasible method of controlling ticks in indigenous cattle would be twice weekly spraying with acaricide during only 2 months of the year in the early wet season to break the pronounced peak in the tick load. However, hand spraying offers no advantage over hand removal of ticks in terms of saving labour. The main advantage of strategic spraying lies in more thorough removal of ticks and possibly prevention of dermatophilosis at a lower cost than year-round use of acaricide. Knowledge of the seasonal pattern of tick load is also valuable for planning the introduction of selected stock with higher genetic potential, but higher susceptibility to tick-borne diseases than exhibited by Bunaji cattle. 相似文献
8.
Current cattle tick control practices and producer attitudes towards tick control in the eastern Cape Province of South Africa are discussed. These were ascertained from answers to a questionnaire survey to which 31.2% of farmers responded. In general, producers favoured intensive tick control. Beef and dairy farmers had a definite preference for synthetic pyrethroid acaricides, the majority followed a 25 times p.a. treatment frequency and most changed acaricides because of price. Beef producers favoured pour-on application of acaricides while the majority of dairy producers utilized plunge dipping. Producers who used hand spray techniques experienced the highest percentage of confirmed acaricide resistance. A costs of R11.27 for acaricide treatment per bovine per annum was calculated from data gained in this survey. A cost index of 2,496 was calculated by relating acaricide cost to the prevailing price of beef in the region. Only a small number of producers used heartwater, babesiosis and anaplasmosis vaccines. Relative tick borne disease mortality ratios indicated higher heartwater mortalities at high acaricide treatment frequencies. These results are discussed in relation to the tick control regimes practised. 相似文献
9.
E. L. K. Laisser S. W. Chenyambuga E. D. Karimuribo G. Msalya M. J. Kipanyula A. J. Mwilawa R. H. Mdegela L. J. M. Kusiluka 《Tropical animal health and production》2017,49(4):813-822
In Tanzania, control of East Coast fever (ECF) has predominantly relied on tick control using acaricides and chemotherapy, little on ECF vaccination, and very little on dissemination regarding animal immunization. In this paper, the prevalence, control measure, and tolerance of Tanzania Shorthorn Zebu (TSHZ) cattle to ECF are reviewed. In addition, the opportunities available for reducing the use of acaricides for the benefit of the farmers in terms of reduction of costs of purchasing acaricides and environmental pollution are described. The tick distribution and epidemiological factors for ECF such as the agro-ecological zones (AEZ), livestock production systems (LPS), strain, and age of the animals are also described. These factors influence the epidemiology of ECF and the distribution of TSHZ strains in different geographic locations of Tanzania. We have further showed that there is a tendency of farmers to select among the strains of TSHZ for animals which can tolerate ticks and ECF and crossbreed them with their local strains with the aim of benefiting from the inherent characteristics of the most tolerant strains. Generally, many strains of TSHZ cattle are tolerant to tick infestation and ECF infection and can be bred to respond to the needs of the people. In this review paper, we recommend that in future, ECF epidemiological studies should account for factors such as livestock production system, agro-climate, breed of animal, tick control strategy, and the dynamic interactions between them. In conclusion, we have demonstrated that an integrated control method involving use of acaricides, immunization, and ECF-tolerant/-resistant animals is required. 相似文献
10.
J L Du Plessis P J Loock C J Lüdemann 《The Onderstepoort journal of veterinary research》1992,59(2):75-89
Several conclusions of importance to studies on the epidemiology of heartwater were drawn from an investigation in which the numbers of adult Amblyomma hebraeum ticks, to which a closed herd of Hereford cattle were exposed over a period of 6 1/2 years, were manipulated. With a tick Cowdria ruminantium infection rate of 3-5%, an endemically stable situation was created by dipping the herd only when an average of 10 adult male and female A. hebraeum ticks were counted on 10 animals. When the average was increased to 15 during the calving period, 97% of calves acquired a tick-mediated immunity at the age of 6 months. Because only adult ticks confined to the hindquarters are counted, this procedure is recommended as a feasible and practical guideline to stock owners wishing to determine a dipping programme that would ensure endemic stability. The indirect fluorescent antibody test gave a true reflection of the infection rate through ticks in calves 3-6 months old, but not in older animals that had been re-infected more than once. This is because on one hand antibody may persist for 2 years after withdrawal from tick exposure and on the other the artificial re-infection of cattle with a tick acquired immunity is not always followed by a rise in antibody titres and may even result in seronegativity. Four cows infected and re-infected through ticks, remained immune to challenge for 2 years after withdrawal from tick exposure. Within the confines of one farm 3 isolates of C. ruminantium that differed in pathogenicity and immunogenicity were recovered from ticks. One of these isolates was almost non-pathogenic to cattle. 相似文献
11.
A survey conducted in five villages in a resource-poor farming community in Qwa-Qwa, using the rapid rural appraisal technique and a questionnaire survey, showed that a significant proportion of the farmers (84%) use traditional or alternative methods to control ectoparasites, while 16% use commercial acaricides (chi2 = 7.1; P < or = 0.05). Alternative control methods included the use of used engine oil, household disinfectant and paraffin. Killing of ticks was the main reason for control (40%), with disease control being second (20%). Other reasons given for controlling ticks were to prevent damage to teats, to provide animals with a clean appearance and to protect hides. Some 40% of farmers were aware of the effects of ticks on their animals. There is a need for farmer education that will provide information on integrated tick management and its advantages over absolute reliance on commercial acaricides. 相似文献
12.
Epidemiology of heartwater in Guadeloupe and in the Caribbean 总被引：4，自引：0，他引：4
At present, heartwater in the Caribbean is known with certainty only on Guadeloupe, Marie Galante and Antigua; the first 2 islands are widely infected. The most important factors responsible for particular aspects of heartwater in Guadeloupe are: Cowdria ruminantium of high virulence. A very resistant cattle population (Creole), not normally clinically affected. A fairly susceptible goat population (Creole) (22% goats born in endemic areas die after experimental inoculation) which, fortunately, includes breeding lines with inherited resistance characteristics. Amblyomma variegatum which is present all over the island and all through the year, but with a low infection rate (1-2% of adult ticks are infected) because of the short period of rickettsemia in infected animals. The low rate of tick infection results in a low endemicity of the disease. For goats, the epidemiologic situation can be regarded as unstable because the low rate of infection in ticks does not allow a natural immunization of the majority of young kids when they still have a non-specific resistance. The possible evolution of heartwater in the Caribbean and in the United States in considered. 相似文献
13.
Danger of introducing heartwater onto the American mainland: potential role of indigenous and exotic Amblyomma ticks 总被引：6，自引：0，他引：6
N Barré G Uilenberg P C Morel E Camus 《The Onderstepoort journal of veterinary research》1987,54(3):405-417
The existence of heartwater on 3 islands of the Central Lesser Antilles and the presence of an efficient vector originating from Africa, Amblyomma variegatum, on most of the islands of this region constitute a serious threat for livestock on the American mainland. The disease can be introduced there either by infected animals or infected ticks. The most likely way is probably the transportation of domestic animals which are heavily infested by ticks. Due to the low rate of infection of ticks in endemic areas and the low rate of infestation of wild animals by ticks, the risk of transportation by migratory birds (among which the cattle egret is the most important) seems negligible compared with domestic animals, especially ruminants and dogs. The establishment and spread of the disease on the mainland could result from indigenous American Amblyomma species, of which at least 2, Amblyomma cajennense and, more especially, Amblyomma maculatum, are experimental vectors. The biological and ecological features of these ticks conform to some extent with the characteristics necessary for them to act as vectors. They are widespread and sufficiently well adapted to ruminants to ensure the continuation of the epidemiological cycle. Disease could evolve in wild life (deer) or, as seems more likely, in livestock, of which the population density is very high on most of the mainland. However, the establishment of the disease is more likely to occur if the well adapted vector of heartwater, Amblyomma variegatum, is introduced as well. This exotic species would find environmental conditions favourable for its survival and spread in most of the tropical and subtropical Western Hemisphere. Protection of the American mainland and the disease-free islands of the area must be based on strict control of domestic animal movement in the Caribbean, on the decrease of the vector population by tick control campaigns and, if possible, on the eradication of Amblyomma variegatum from the focus of heartwater on the islands. 相似文献
14.
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
15.
Ixodid ticks were collected from domestic animals, mainly cattle, in 11 administrative zones covering 84 districts in central Ethiopia over a period of 2 years (July 1996 to June 1998). Nineteen tick species were identified. Four of these belonged to the genus Amblyomma, one to Boophilus, two to Haemaphysalis, three to Hyalomma and nine to Rhipicephalus. Amblyomma variegatum and Rhipicephalus evertsi evertsi were present in all 11 administrative zones and, with the exception of Afar, Boophilus decoloratus was present in nearly every district in which collections were made. These three species constituted more than 50% of all ticks collected. Amblyomma cohaerens and Rhipicephalus bergeoni were common in the west of the survey region and Rhipicephalus pulchellus in the east. Except for B. decoloratus, of which more females than males were collected, the numbers of male ticks recovered were equal to or exceeded those of females. Mortality in crossbred dairy cattle caused by heartwater (Cowdria ruminantium infection) was reported during the survey period. An integrated approach to tick control is suggested. 相似文献
16.
Yawa Mandla Nyangiwe Nkululeko Jaja Ishmael Festus Kadzere Charles T. Marufu Munyaradzi Christopher 《Tropical animal health and production》2020,52(6):3005-3013
The aim of this study was to reveal communal farmer’s knowledge, attitudes and practice on ticks and tick-borne diseases affecting cattle, tick control methods used and their knowledge on acaricide resistance. A total of 160 structured questionnaires are prepared and randomly administered to cattle farmers in Sinqu and Elundini communities in the Eastern Cape Province, South Africa. Associations between the area, gender, age, employment, source of income, level of education and farming experience were statistically tested using Chi-square test. Gall sickness (63%) was the most prevailing tick-borne disease in cattle during the summer season (61%). About 59% of the farmers had no knowledge of the effect of tick-borne diseases on cattle production, and 78% of respondents reported that ticks are the major challenge to cattle farming. Pour-on (61%) was the most commonly used acaricidal treatment system with every fortnight (40%) treatment frequency during the summer season and (31%) during the winter season. Pyrethroids (73%) were the most used acaricide compounds to control ticks, and about 65% of respondents perceived to have no knowledge of the use of ethnoveterinary medicines used to control ticks. Inefficacy of acaricide (44%) and undipped animals (42%) were regarded as the major contributing factors to the increased tick population and acaricide resistance. About 85% of respondents perceived that they do not practice acaricide rotation and 88% of the respondents had no knowledge of the acaricide resistance. Within the context of this study, ticks and tick-associated diseases are perceived by these farmers as the most important disease problem their cattle face. Thus, knowledge regarding the epidemiology of ticks and tick-borne diseases is key to control strategies, and farmer training should be encouraged to achieve better control of ticks and the diseases they transmit.
相似文献17.
Tick fever is an important disease of cattle where Rhipicephalus (Boophilus) microplus acts as a vector for the three causal organisms Babesia bovis, Babesia bigemina and Anaplasma marginale. Bos indicus cattle and their crosses are more resistant to the clinical effects of infection with B. bovis and B. bigemina than are Bos taurus cattle. Resistance is not complete, however, and herds of B. indicus-cross cattle are still at risk of babesiosis in environments where exposure to B. bovis is light in most years but occasionally high. The susceptibility of B. indicus cattle and their crosses to infection with A. marginale is similar to that of B. taurus cattle. In herds of B. indicus cattle and their crosses the infection rate of Babesia spp. and A. marginale is lowered because fewer ticks are likely to attach per day due to reduced numbers of ticks in the field (long-term effect on population, arising from high host resistance) and because a smaller proportion of ticks that do develop to feed on infected cattle will in turn be infected (due to lower parasitaemia). As a consequence, herds of B. indicus cattle are less likely than herds of B. taurus cattle to have high levels of population immunity to babesiosis or anaplasmosis. The effects of acaricide application on the probability of clinical disease due to anaplasmosis and babesiosis are unpredictable and dependent on the prevalence of infection in ticks and in cattle at the time of application. Attempting to manipulate population immunity through the toleration of specific threshold numbers of ticks with the aim of controlling tick fever is not reliable and the justification for acaricide application should be for the control of ticks rather than for tick fever. Vaccination of B. indicus cattle and their crosses is advisable in all areas where ticks exist, although vaccination against B. bigemina is probably not essential in pure B. indicus animals. 相似文献
18.
Tick control methods used by resource-limited farmers and the effect of ticks on cattle in rural areas of the Eastern Cape Province,South Africa 总被引：1，自引：1，他引：0
A survey to document tick control methods used by resource-limited farmers in the control of cattle ticks in the Eastern Cape
Province of South Africa was conducted by interviewing 59 cattle farmers using structured questionnaires and general conversation.
Information collected was on external parasites of cattle, their effects and their control methods. Ticks were reported to
be a major problem causing diseases like anaplasmosis (89.8%), babesiosis (55.9%) and ehrlichiosis (16.9%), as well as wounds
that predispose to screwworm infestation, tick worry and teat damage to cows troubling farmers in their farming enterprises.
The main tick control methods were; acaricides provided by government, however 94.9% of the farmers interviewed were of the
opinion that the dip wash is not effective in killing the ticks. As a result, farmers complement the government dipping service
with their own initiatives like spraying with conventional acaricides (22%), household disinfectants such as Jeyes fluid (18.6%),
used engine oil (10.2%), chickens (5.1%), manual removal (5.1%), and pouricides (1.7%). In addition, some farmers also use
plants (6.8%), mainly the leaf of Aloe ferox and the bark of Ptaeroxylon obliquum. The study revealed ticks to be a major problem in the study area. 相似文献
19.
J Schr?der 《The Onderstepoort journal of veterinary research》1987,54(3):517-520
This paper reviews available literature on the efficacy of acaricides against Amblyomma hebraeum and other tick species, and presents information on tests done with registered chemicals in the laboratory. Little published information is available on the efficacy of chemicals specifically against A. hebraeum. A host of formulations are registered for use as acaricides on cattle, sheep, and goats in South Africa and thus, by implication, against this species. Resistance has only been described to arsenic and toxaphene in Southern Africa; the other registered products are generally considered to be effective. In contrast, many efficacy tests of various chemicals in different formulations against other Amblyomma spp. have been described. These publications have mainly emanated from the USA, where bite-wounds of these ticks serve as oviposition sites for screwworm flies. In this paper, Amblyomma maculatum and Amblyomma variegatum are included as potential heartwater vectors. The acaricidal efficacy of a number of compounds, representative of different chemical classes, was tested in South Africa against an arsenic and organochlorine resistant strain of A. hebraeum. The engorged adult female immersion method was used. A disconcerting discovery was that several of these registered products failed to control this tick when used at their recommended concentrations. It is concluded that many chemicals which fail against A. hebraeum on cattle do so because of insufficient persistence. Exposure of this tick to lower levels of existing chemicals, but for longer periods, ought to provide satisfactory control for many years. 相似文献
20.
A ten-year review of commercial vaccine performance for control of tick infestations on cattle 总被引：3，自引：0，他引：3
de la Fuente J Almazán C Canales M Pérez de la Lastra JM Kocan KM Willadsen P 《Animal health research reviews / Conference of Research Workers in Animal Diseases》2007,8(1):23-28
Ticks are important ectoparasites of domestic and wild animals, and tick infestations economically impact cattle production worldwide. Control of cattle tick infestations has been primarily by application of acaricides which has resulted in selection of resistant ticks and environmental pollution. Herein we discuss data from tick vaccine application in Australia, Cuba, Mexico and other Latin American countries. Commercial tick vaccines for cattle based on the Boophilus microplus Bm86 gut antigen have proven to be a feasible tick control method that offers a cost-effective, environmentally friendly alternative to the use of acaricides. Commercial tick vaccines reduced tick infestations on cattle and the intensity of acaricide usage, as well as increasing animal production and reducing transmission of some tick-borne pathogens. Although commercialization of tick vaccines has been difficult owing to previous constraints of antigen discovery, the expense of testing vaccines in cattle, and company restructuring, the success of these vaccines over the past decade has clearly demonstrated their potential as an improved method of tick control for cattle. Development of improved vaccines in the future will be greatly enhanced by new and efficient molecular technologies for antigen discovery and the urgent need for a tick control method to reduce or replace the use of acaricides, especially in regions where extensive tick resistance has occurred. 相似文献