Immunisation of cattle against theileriosis in Nakuru District of Kenya by infection and treatment and the introduction of unconventional tick control.

One hundred and one cross European-Boran cattle (50 cows and 51 calves), on a farm in Nakuru District, Kenya, were immunised against theileriosis using Theileria parva lawrencei and Theileria parva parva stocks from another district of Kenya. The stabilates used were T.p.lawrencei (Mara III) used at 10(-1.7) dilution and T.p.parva (Kilae) used at 10(-1.0) dilution. The stabilates were combined and inoculated simultaneously with a short-acting formulation of oxytetracycline hydrochloride given intramuscularly at 10 mg kg-1 body weight and was repeated on Day 4 after inoculation of the stabilate. Most of the theileriosis challenge on the farm was thought to be derived directly from the African buffalo (Syncerus caffer). Nine percent of the cattle had significant indirect fluorescent antibody (IFA) titres before the immunisation and 99% after immunisation. The immunised cattle were exposed to tick-borne disease challenge on the farm by withdrawal of acaricide cover. The immunised cattle were divided into five groups plus two susceptible control cows and two calves for each group. Cattle in four of the groups had acaricidal ear tags, each group having a different type, applied to both ears and the fifth group remained untagged. The animals remained without conventional acaricide application for 134 days. Ten out of 20 (50%) non-immunised control cattle became T.p.lawrencei reactors which only one out of 97 (1%) of the immunised cattle reacted. A frequent complication noted was mild infections due to unidentified Theileria sp. which required expert differentiation from T.parva infections. An additional group of ten steers whose tick load was removed by hand at weekly intervals was introduced 79 days after exposure; these had no tick control and four became T.p.lawrencei reactors. Of 12 calves born during the exposure period and without tick control, four became theilerial reactors and one died. The application of acaricidal tags however, reduced tick infestation levels considerably compared with untagged controls but did not prevent transmission of theileriosis with the possible exception of tags on Group 4. A number of transient low grade fevers were noted and attributed to Theileria sp., Ehrlichia bovis, Ehrlichia (Cytoecetes) ondiri and Borrelia theileri infections, none of which were fatal. One immunised animal died of acute dual infection of Babesia bigemina and Borrelia theileri after acaricide control by spraying was re-introduced but no Anaplasma infections were detected. An analysis of the economic effects of immunisation was made.     

Exposure of cattle immunized with different stocks of Theileria parva to buffalo-associated Theileria challenge on two game parks in Zimbabwe.

Eight cattle immunized with cattle-derived Theileria parva Boleni stabilate together with six susceptible controls were released in Dombawera Game Park on the Highveld of Zimbabwe. This coincided with Rhipicephalus appendiculatus nymphal activity. The cattle grazed together with African buffaloes (Syncerus caffer) and were not treated against tick infestation. The nymphal tick infestation was high, and seven of the eight immunized cattle and three of the controls had severe and fatal reactions. Subsequently, two stocks of Theileria parva to be tested for their immunizing abilities were prepared-one from adult ticks which were fed as nymphs on one of the sick control animals (Dom 268) and the other from adult ticks collected from pastures grazed by buffaloes (Bv-1). Two groups of cattle were immunized with either the Dom 268-derived strain (eight animals) or the Bv-1-derived strain (four animals). These together with three non-immunized controls, were released in Bally Vaughaun Game Park in the Highveld, where buffaloes are present, during the season of nymphal tick activity. A third group of five cattle, immunized with stabilate Bv-1, and three non-immunized controls were released at the same site during the season of adult tick activity. The nymphal and adult tick infestations of the cattle were large and more than 2000 nymphs and 1000 adult ticks were counted per animal. Cattle were treated with a pyrethroid pour-on preparation to control the tick infestation and screw-worm strike. The immunized cattle in the three groups survived the theileriosis challenge for a period of 18 months, but the non-immunized control cattle suffered a severe and fatal theileriosis 19-23 days after being placed on the pasture.     

Communal cattle farmer’s knowledge,attitudes and practices on ticks (Acari: Ixodidae), tick control and acaricide resistance

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.

     

Epidemiological observations on theileriosis following field immunisation using infection and treatment

Thirty-seven high grade cattle were immunised against Corridor disease (Theileria parva lawrencei infection) on a farm with a history of heavy and often lethal theilerial challenge. Nineteen cattle were immunised by treating with two doses of long-acting oxytetracyclines given at 20 mg/kg on days 0 and 4 after sporozoite stabilate inoculation, while the other 18 were treated with naphthoquinone buparvaquone, given as a single dose of 2.5 mg/kg simultaneously with stabilate inoculation. All the cattle underwent subclinical theilerial reactions with all but two developing high antibody titres on the IFAT test against T. parva schizont antigen by day 35 after the immunisation. Both buparvaquone and long-acting oxytetracycline appeared equally effective in the immunisation. To date, 26 months later, only two cases of theileriosis parasitologically characteristic of T. p. parva have been reported in the immunised cattle. Following the two cases, investigations showed that when uninfected Rhipicephalus appendiculatus nymphal ticks were deliberately fed on healthy resident cattle on the farm, the resultant adult ticks transmitted acute and lethal theilerial infections to five out of five susceptible cattle. The resultant infections were parasitologically characteristic of T. p. parva infections. Furthermore, the monoclonal antibody profiles of schizont infected cell lines from these infections appeared to be characteristic of T. p. parva. It was thus concluded that resident cattle on the farm could be a potential source of T.p. parva infection which had broken through the immunity of T.p. lawrencei immunised cattle and could constitute a reservoir of theilerial infection for ticks and hence to susceptible stock on the farm.     

Transformation of Theileria parva derived from African buffalo (Syncerus caffer) by tick passage in cattle and its use in infection and treatment immunization.

A sporozoite stabilate (St. 199) of Theileria parva was obtained by feeding nymphal Rhipicephalus appendiculatus on an African buffalo (Syncerus caffer) and was used to immunize cattle by the infection and treatment method. Nymphal ticks were applied to one of the steers 90 days later and it was shown that the resultant adult tick had become infected. Using tick/cattle passage, two passage lines of T. parva were established. By the fifth tick/cattle passage, the parasite stocks had changed their behaviour to that of T. parva derived from cattle as the parasite produced relatively high schizont parasitosis and piroplasm parasitaemia in cattle, and had become highly infective to ticks. At various passage levels the parasite populations were characterized by behaviour and by monoclonal antibodies against T. parva schizonts using infected cell culture isolates from cattle during acute infections. The monoclonal antibody profile showed little evidence of antigen change of the parasite during passage through cattle, which was confirmed in a two-way cross-immunity experiment using sporozoite stabilate derived from ticks obtained from the buffalo and fourth passage in cattle. The implication of these results, particularly in relationship to immunization of cattle against T. parva derived from buffalo, is discussed.     

Epidemiological observations of Zimbabwean theileriosis: disease incidence and pathogenicity in susceptible cattle during Rhipicephalus appendiculatus nymphal and adult seasonal activity.

Fifty-nine Hereford cattle susceptible to tick-borne diseases were used as tracer animals to assess the tick challenge and pathogenicity of Theileria parva under field conditions in Zimbabwe. They were moved periodically in groups of five to three commercial farms (one group consisted of four) during seasons of Rhipicephalus appendiculatus nymphal and adult activity. All tracer cattle were herded together with the farm cattle but were not dipped. The nymphal tick counts were high on two of the farms (up to 2000 per animal) but were very low on the third farm (less than ten per animal). On the three farms, 19 out of 24 (76%) tracers had patent Theileria schizonts. There was a range of clinical manifestations of theileriosis with acute and fatal infections occurring on one farm. The adult R. appendiculatus infestations during the wet season numbered 120-800 per animal on the three farms. The disease transmitted by the adults was very pathogenic on the three farms; 30 out of 35 (86%) had severe theileriosis infections. Cattle, which survived the nymphal diseases challenge, showed various degrees of immunity to subsequent T. parva challenge transmitted by adult ticks. Therefore, 13 out of 18 (72%) of these cattle had a second disease episode and the case fatality rate on the three farms was 46%. The factors which determined the epidemiological status of Theileria challenge on the farms, such as the farming systems and presence of wild animals, are discussed.     

Cloned Theileria parva produces lesser infections in ticks compared to uncloned T. parva despite similar infections in cattle

Experimental transmissions of cloned Theileria parva in cattle with Rhipicephalus appendiculatus ticks were compared to transmissions with uncloned T. parva during studies on the potential for genetic recombination during syngamy of Theileria to produce antigenic diversity for evasion of bovine immunity. Prevalence and abundance of T. parva infection in adult ticks, which resulted from the feeding of nymphs on the calves, were significantly higher in the uncloned compared to the cloned T. parva. Development of sporoblasts of T. parva in the ticks to produce infective sporozoites was similar. There was no statistically significant difference in the clinical course of infection in cattle between cloned and uncloned T. parva. It was concluded that cloned T. parva has characteristics that reduce its viability during the tick stages of its life cycle.     

Comparison of long acting oxytetracycline and parvaquone in immunisation against East Coast fever by infection and treatment

Two groups of five cattle were immunised with a field isolate of Theileria parva as stabilate and simultaneously treated with long acting oxytetracycline or parvaquone in early clinical disease. The oxytetracycline group suffered a marked fall in leucocyte count and one animal died during immunisation. The parvaquone group suffered a less severe fall in leucocyte count and all survived. The surviving immunised cattle were immune to homologous challenge but susceptible to subsequent challenge with T p lawrencei.     

Effect of timing and intensity of challenge following immunization against East Coast fever

When groups of Theileria parva parva Muguga-immunized cattle were given a homologous lethal challenge at different times after immunization, it was found that 4/6, 5/6, 6/6 and 6/6 animals survived when challenged on Days 5, 10, 20 and 30, respectively, post-immunization. With a heterologous challenge (T.p.parva Marikebuni), 2/6, 5/6, 4/6, 4/6 and 5/6 cattle survived when challenged on Days 5, 10, 20 and 30, respectively, after immunization. All controls, except one, died of East Coast fever (ECF). The survivor underwent severe ECF and recovered after a prolonged convalescence. When two T.p.parva Muguga-immunized animals were each given homologous challenge by application of 1000 infected ticks (infection rate of 20 infected acini (i.a.) per tick), both survived a mild ECF reaction. When groups of T.p.parva Muguga- or T.p.parva Muguga/Marikebuni-immunized cattle were challenged with different doses of T.p.parva Muguga sporozoites (equivalent of 140, 1400 and 14,000 i.a. per animal), 28/29 cattle survived. All controls died of ECF. It was concluded that cattle could be safely exposed to tick challenge 1 week after immunization by infection and treatment using appropriate immunizing stock(s). Massive homologous challenge did not break through the immunity induced by the immunization procedure.     

Disease at the wildlife-livestock interface: Acaricide use on domestic cattle does not prevent transmission of a tick-borne pathogen with multiple hosts

Several prominent and economically important diseases of livestock in East Africa are caused by multi-host pathogens that also infect wildlife species, but management strategies are generally livestock focused and models of these diseases tend to ignore the role of wildlife. We investigate the dynamics of a multi-host tick-borne disease in order to assess the efficacy of tick control from an ecological perspective. We examined the efficacy of a widespread measure of tick control and developed a model to explore how changes in the population of ticks due to control measures on cattle impact dynamics of Theileria parva infection in a system with two primary host species, cattle and Cape buffalo (Syncerus caffer). We show that the frequency of acaricide application has a significant impact on the tick population both on the host and in the environment, which can greatly reduce the pathogen load in cattle. We also demonstrate that reducing the tick population through cattle-related control measures is not sufficient to diminish disease transmission in buffalo. Our results suggest that under current control strategies, which target ticks on cattle only, T. parva is likely to remain a significant problem in East Africa, and require the continued use of acaricides, which has significant economic and ecological consequences.     

Seasonal pattern of tick load in Bunaji cattle in the subhumid zone of Nigeria

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.     

Laboratory and field investigations into the Theileria parva carrier-state in cattle in Zimbabwe.

The Theileria parva carrier-state in cattle on commercial farms on Zimbabwe was investigated using parasitological and serological methods. The proportion of cattle showing Theileria piroplasms on two farms, which had recent histories of disease outbreaks, were 64% (n = 106, total of heifers and weaned calves examined) and 71.5% (n = 60) while the proportion of T. parva antibodies for the same animals were 59% and 98.5%, respectively. On four farms where no cases of the disease occurred for over 10 years, the average proportion of animals showing piroplasms and antibodies were 55.4% (range 32-82, n = 223) and 73% (range 47-91, n = 223), respectively. However, on another three farms which had no history of theileriosis outbreaks these proportions were very low, being 11.4% (0-24, n = 157) for piroplasms and 12.2% (5-23, n = 157) for antibodies. The mean infection rate in unfed Rhipicephalus appendiculatus adults collected from farms with a high prevalence of cattle which were carriers of Theileria piroplasms during the tick activity season was 29% (range 12-60%) with 9.3 (range 2-18.7) mean infected acini per infected tick. The infectivity of different tick batches to susceptible cattle produced a wide spectrum of theileriosis reactions. Laboratory controlled experiments were carried out to study the persistence of T. parva (Boleni) piroplasms in cattle immunized with this strain as well as its infectivity for ticks and its subsequent transmissibility to cattle. Examination of the salivary glands of 15 batches of ticks collected from six immunized cattle on three different occasions over 18 months showed that none were infected with Theileria parasites. However, the infectivity of other ticks in the same batches to susceptible animals was demonstrated 6, 10 and 18 months after cattle had been immunized with Boleni stabilate.     

Rhipicephalus zambeziensis as a vector of bovine theileriae

Rhipicephalus zambeziensis was shown experimentally to transmit Theileria parva parva in cattle from nymph to adult and Theileria parva lawrencei, Theileria parva bovis and Theileria taurotragi from larva to nymph and nymph to adult. In a single trial the tick failed to transmit Theileria mutans. The tick is believed to be a vector of T. parva lawrencei in the field in Zimbabwe.     

The effect of East Coast fever immunisation and different acaricidal treatments on the productivity of beef cattle

A trial was performed on a farm in the Coast Province of Kenya to study the effects of East Coast fever immunisation and different acaricidal treatments on the productivity of immunised and unimmunised beef cattle. Eighty cattle were immunised against Theileria parva parva (Marikebuni) by the infection and treatment method and a similar group was left as an unimmunised control. Immunisation had no deleterious effect on the cattle. After immunisation, the immunised and control groups were each subdivided into four groups of 20 and each subgroup was managed under a different tick control regimen. The tick control regimen were, acaricidal spraying twice a week or once every three weeks, the application of acaricide-impregnated ear-tags, and no tick control. During a nine-month exposure period there were 18 cases of East Coast fever among the 80 immunised cattle, three which were severe and the others mild. Among the 80 unimmunised cattle there were 57 cases of East Coast fever, 50 of which were severe. The highest morbidity and mortality occurred in the groups under limited tick control or without tick control. Overall weight gain in the immunised cattle, irrespective of the tick control regimen, was better than the weight gain in the unimmunised groups. Within the immunised groups, the weight gain of the cattle sprayed twice weekly was comparable to the weight gain of the animals with acaricidal ear-tags and was significantly higher than the weight gains in the groups sprayed once every three weeks or with tick control. Preliminary cost/benefit analysis showed that it was uneconomical to maintain unimmunised cattle under limited or no tick control.(ABSTRACT TRUNCATED AT 250 WORDS)     

PCR-based detection of blood parasites in cattle and adult Rhipicephalus appendiculatus ticks

To ascertain the infection rate for tick-borne pathogens in Zambia, an epidemiological survey of Theileria parva, Babesia bigemina and Anaplasma marginale in traditionally managed Sanga cattle was conducted using PCR. Of the 71 native Zambian cattle, 28 (39.4%) were positive for T. parva, 16 (22.5%) for B. bigemina and 34 (47.9%) for A. marginale. The mixed infection rate in cattle was 8.5% (6/71), 16.9% (12/71), 7.0% (5/71) and 2.8% (2/71) for T. parva/B. bigemina, T. parva/A. marginale, B. bigemina/A. marginale and T. parva/B. bigemina/A. marginale, respectively.To predict the risk for transmission of tick-borne pathogens from ticks to cattle, a total of 74 Rhipicephalus appendiculatus ticks were collected from a location where cattle had been found positive for T. parva. Of the ticks collected, 10 (13.5%) were found to be PCR-positive for T. parva. The results suggest that the infection rate for tick-borne pathogens was relatively high in Sanga cattle and that adult R. appendiculatus ticks were highly infected with T. parva.     

一种牛源扇头蜱及其携带梨形虫种类鉴定

为了鉴定从汉中市牛体表采集到的蜱种类及其携带病原梨形虫(Piroplasma)的种类,在形态学初步观察的基础上,用PCR技术基于线粒体16SrDNA对蜱种类进行了分子鉴定,并基于梨形虫18S rRNA基因分别检测蜱体内携带巴贝斯虫属(Babesia)、泰勒虫属(Theileria)等病原情况.结果显示,所采集到的67只...     

Molecular detection of piroplasms in ixodid ticks infesting cattle and sheep in western Oromia, Ethiopia

In Ethiopia, ticks and tick-borne diseases are widely distributed and contribute to important economic losses. Several studies investigated the prevalence and species composition of ticks infesting ruminants; however, data on tick-borne pathogens are still scarce. During the study period from October 2010 to April 2011, a total of 1,246 adult ticks and 264 nymphs were collected from 267 cattle and 45 sheep in Bako District, western Oromia, Ethiopia. The study showed infestation of 228/267 (85.4 %) cattle and 35/45 (77.8 %) sheep with adult ticks. Overall, eight tick species, belonging to three genera (Amblyomma, Rhipicephalus, Hyalomma), were identified and Amblyomma cohaerens (n?=?577), Rhipicephalus evertsi evertsi (n?=?290), Rhipicephalus (Boophilus) decoloratus (n?=?287), and Amblyomma variegatum (n?=?85) were the more prevalent species. A statistically significant host preference in A. cohaerens for cattle and R. evertsi evertsi for sheep was noticed. Molecular detection of piroplasms, performed only for adult ticks of two species of the genus Rhipicephalus (R. evertsi evertsi and R. decoloratus), revealed an overall prevalence of 4 % (8/202) Theileria buffeli/sergenti/orientalis, 0.5 % (1/202) Theileria velifera, and 2 % (4/202) Theileria ovis. The study showed that tick infestation prevalence is considerably high in both cattle and sheep of the area, but with a low intensity of tick burden and a moderate circulation of mildly pathogenic piroplasm species.     

Infection of African buffalo (Syncerus caffer) and cattle with Theileria parva lawrencei after serial passage in cattle

The infectivity of a Theileria parva lawrencei stabilate, from a stock derived from an African buffalo (Syncerus caffer) in the Serengeti National Park, Tanzania, was investigated. In the first experiment a buffalo and three cattle were inoculated with a stabilate from a stock passaged three times in cattle. All cattle developed fatal theilerial infections. Isolations from the buffalo by tick feeding and cell culture isolation showed that it was infected with T p lawrencei at the time of inoculation, but the second isolation made 19 days after inoculation behaved like T p parva in cattle, developing a high parasitosis, while the third isolation made three months later behaved like T p lawrencei with low parasitosis. It was concluded that two biological types of T parva could exist in a buffalo at one time, but it was not shown that the buffalo had become a carrier of T p lawrencei adapted to cattle. In the second experiment two buffaloes and three cattle were inoculated with T p lawrencei (Serengeti) stabilate which had been passaged six times through cattle and ticks. The two buffaloes had mild theilerial infections and developed serological titres in the indirect fluorescent antibody test, but the cattle had fatal infections. Tick and cell culture isolations of T parva were possible during the clinical reactions of the buffaloes, but no carrier state was demonstrated. Theileria-infected cell lines were established from the buffaloes and the cattle and were examined using monoclonal antibodies against T parva schizonts.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunisation of cattle against theileriosis in Coast Province, Kenya: laboratory evaluation of a Theileria parva parva stabilate for use in 'infection and treatment' immunisation in the field

Theileria parva parva Marikebuni stock, previously shown to give good protection to immunised cattle in Kilifi District, Coast Province of Kenya, was chosen for large scale immunisation in the district. A large sporozoite stabilate was prepared and evaluated for efficacy and safety in the 'infection and treatment' method, using a long or short acting formulation of oxytetracycline. Susceptible cattle were infected with selected doses of stabilate (10(0), 10(-1), 10(-1.7) and left either as untreated controls, or treated with one of the two oxytetracycline formulations. It was concluded that stabilate dilution at 10(-0.7) or 10(-1) in combination with either formulation of oxytetracycline would effect satisfactory immunisation. The short acting oxytetracycline treatment was judged to be the most efficacious in protecting cattle against homologous challenge. On heterologous challenge it was found that T p parva Marikebuni immune cattle were protected against seven T p parva stocks from Kilifi District and also against four stocks of T p parva from other areas of Kenya. In addition, the Marikebuni stock provided partial protection against challenge by T p lawrencei stocks. Furthermore, cattle immune to T p parva and T p lawrencei were protected against lethal challenge of T p parva Marikebuni stock. Thus, it appears that large scale immunisation of cattle against theileriosis in Kilifi District could be undertaken using the Marikebuni stock. With continued assessment, this stock could provide a master theilerial stock for immunisation against cattle theileriosis in areas free of buffaloes elsewhere in Kenya.