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Maloo SH Thorpe W Kioo G Ngumi P Rowlands GJ Perry BD 《Preventive veterinary medicine》2001,52(1):1-16
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
2.
Maloo SH Ngumi P Mbogo S Williamson S Thorpe W Rowlands GJ Perry BD 《Preventive veterinary medicine》2001,52(1):31-41
Two experiments were carried out to identify the target population of cattle for immunisation against East Coast fever (ECF) using the infection-and-treatment method. Firstly, a sentinel-calf study was used to determine the age window for ECF immunisation by determining ages at clinical detection of infection with Theileria parva. Six groups of five naive cross-bred (Bos taurus/Bos indicus) male calves, introduced at intervals of 2 months at a mean age of 26 days, were exposed to natural tick challenge on a high ECF-risk, small-holder farm in the coastal lowland, coconut-cassava agro-ecological zone of coastal Kenya. Secondly, a challenge study evaluated the relationship between the presence of T. parva antibodies and immunity. Ten indigenous adult Zebu cattle and nine Zebu young stock purchased from farmers in the same zone, and eight cross-bred calves (survivors of the sentinel-calf study) were challenged with 10 times the immunising dose of T. parva Marikebuni stock. Twenty-four of these 27 cattle had high antibody titres before challenge. Two cross-bred calves, obtained from an ECF-free area and seronegative to T. parva schizont antigen, also were challenged and used as susceptible controls. Twenty-five (83%) of the 30 sentinel calves contracted ECF over an age range of 36-116 days (mean 72 days). The remaining five calves died of other causes within 2 months of arrival on the farm. Fourteen of the 25 calves survived the infection and developed antibodies to T. parva. Despite tick control, seven of these 14 calves had a second episode of ECF and two died. In total, 13 of the 25 calves that contracted ECF died. Only one of 19 indigenous Zebu animals developed clinical ECF when challenged with T. parva Marikebuni (mild clinical signs with spontaneous recovery). Of the eight cross-bred survivors from the first experiment, only one succumbed to ECF when challenged and it died. Both susceptible cross-bred calves developed severe clinical signs of ECF and one died. The experimental studies show that in the high ECF-risk areas of the coconut-cassava zone of coastal Kenya, immunisation against ECF in cross-bred (B. taurus/B. indicus) cattle should be targeted at an early age (preferably within 1-2 months of birth). 相似文献
3.
P N Ngumi A S Young D Lampard S K Mining S G Ndungu A C Lesan S M Williamson A Linyonyi D P Kariuki 《Veterinary parasitology》1992,43(1-2):15-24
Three experiments were undertaken to determine the efficacy of different doses of buparvaquone in the infection and treatment immunization of cattle against Theileria parva derived from African buffalo (Syncerus caffer). Two of these experiments also compared buparvaquone with standard doses of long- and short-acting formulations of oxytetracycline. In addition, different dilutions of stabilates were used in the experiments. In the first experiment, a 10(-1.0) dilution of stabilate was used to infect groups of cattle treated with buparvaquone at doses of between 5 and 0.625 mg kg-1 body weight (bwt) on Day 0 after infection. All control cattle developed severe theileriosis and none of the treatment regimes (including those utilizing long-acting oxytetracycline) prevented the development of theileriosis. Treatment with buparvaquone at 2.5 mg kg-1 bwt or oxytetracycline gave the most satisfactory results. In the second experiment when the sporozoite dose was reduced to 10(-2.0) dilution, buparvaquone treatment at 5 and 2.5 mg kg-1 bwt and short- and long-acting formulations of oxytetracycline reduced reactions greatly. While all the oxytetracycline treated animals produced a serological response and were immune to a 50-fold higher challenge with the immunizing stabilate, several animals in the buparvaquone groups did not show a serological response and were not immune to challenge. In the third experiment, groups of cattle were infected with 10(-1.2), 10(-1.4) and 10(-1.6) dilutions of stabilate and were treated with 2.5 mg kg-1 bwt of buparvaquone. No animals developed severe theileriosis and all seroconverted. On homologous challenge, however, two out of 14 cattle showed severe reactions. It was concluded that further work on immunization using buparvaquone treatment at 2.5 mg kg-1 bwt and 10(-1.6) dilution of the stabilate would have to be carried out before such a system could be used in the field. 相似文献
4.
J.M. Gachohi P.M. Kitala P.N. Ngumi R.A. Skilton B. Bett 《Preventive veterinary medicine》2013,108(2-3):103-113
The primary objective of this study was to assess the impact of Rhipicephalus appendiculatus tick presence (exposure variable) on Theileria parva infection seroprevalence (outcome variable) in a group of cattle belonging to a farm using population attributable fractions (PAF). The analyses were based on a representative sample of 80 traditional smallholder mixed farms. The farms were selected by first stratifying the population administratively and implementing a multistage random sampling in Mbeere district in Kenya. The PAFs were estimated using the stratified, Bruzzi, and sequential partitioned PAF approaches. A secondary objective was, thus, to evaluate the impact of the approaches on the PAF estimates. The stratified and Bruzzi approaches estimated proportion of T. parva infection cases directly attributable to the exposure after controlling for confounding by agro-ecological zone (AEZ). The sequential partitioned PAF approach estimated a PAF associated with exposure after adjusting for any effect that the AEZ may have had by influencing the prevalence of the exposure. All analyses were carried out at the farm level where a farm was classified as infested if the tick was found on cattle on a farm, and infected if at least one animal on a farm was positive for T. parva antibodies. Variance estimation for PAFs was implemented using ‘delete-a-group’ jackknife re-sampling method. The stratified PAF (26.7% [95% CI: 9.0%, 44.4%]) and Bruzzi PAF (26.4% [95% CI: 9.6%, 43.2%]) were consistent in estimating a relatively low impact of farm vector tick presence with a relatively high level of uncertainty. The partitioned PAF (15.5% [95% CI: 1.5%, 29.6%]) suggested that part of the impacts estimated using the stratified PAF and Bruzzi approaches was driven by AEZ effects. Overall, the results suggested that under endemic instability in Mbeere district, (1) presence of R. appendiculatus was not a good indicator of T. parva infection occurrence on a farm; (2) ecological variation could play a role in determining infection impacts. This study provides a preliminary basis for evaluating the potential value and utility of estimating PAFs for variables amenable to control in tick-borne diseases (TBDs) epidemiological studies. 相似文献
5.
Ndungu SG Ngumi PN Mbogo SK Dolan TT Mutugi JJ Young AS 《The Onderstepoort journal of veterinary research》2005,72(1):7-11
Theileria parva-na?ve Friesian (Bos taurus), Boran (Bos indicus) and Maasai Zebu steers (B. indicus) were infected with a T. parva sporozoite stabilate dose which had previously been shown to induce an estimated 50% mortality rate in Boran cattle. All the cattle developed patent infections with no significant differences in the length of the prepatent period to development of macroschizonts (P > 0.05) between the three groups. Clinical theileriosis occurred in all eight the Friesians (100%), five out of nine Borans (55.6%) and two out of five Zebus (40%). Three of the Friesians (37.5%), and two of the Borans (22.2%) died of theileriosis. The different cattle types were equally susceptible to the infective dose used as indicated by the length of the prepatent periods, but there was a marked difference in their development of clinical theileriosis. The gradation in resistance to disease confirms the findings of earlier less critical studies and identifies these cattle breeds as suitable for investigations into the mechanisms of resistance to theileriosis. 相似文献
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J J Mutugi A S Young A C Maritim S G Ndungu S K Mining A Linyonyi P N Ngumi B L Leitch S P Morzaria T T Dolan 《Research in veterinary science》1989,47(2):170-177
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. 相似文献
7.
A S Young J J Mutugi D P Kariuki D Lampard A C Maritim P N Ngumi A Linyonyi B L Leitch S G Ndungu A C Lesan 《Veterinary parasitology》1992,42(3-4):225-240
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. 相似文献
8.
A C Maritim A S Young A C Lesan S G Ndungu D A Stagg P N Ngumi 《Veterinary parasitology》1992,43(1-2):1-14
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. 相似文献
9.
Muraguri GR Ngumi PN Wesonga D Ndungu SG Wanjohi JM Bang K Fox A Dunne J McHardy N 《Research in veterinary science》2006,81(1):119-126
East Coast fever, caused by the protozoan parasite Theileria parva, kills about 600,000 cattle annually in Africa. The hydroxynaphthoquinone compound buparvaquone (BPQ) is curative. Sixteen calves were infected with T. parva. On manifestation of disease symptoms, eight were injected with the original (pioneer) BPQ product and eight with a test product containing BPQ. All 16 calves were cured by one injection of 2.5 mg BPQ/kg bodyweight. The concentration of BPQ in blood plasma was monitored by HPLC. The mean observed C(max) of BPQ was 0.229 and 0.253 microg/mL of plasma, the mean observed time to reach this concentration (T(max)) was 2.62 and 2.12 h and the AUC (area under curve) was 4.785 and 4.156 microg h/mL, respectively, for the pioneer and test product. Considerable variations occurred in the plasma concentration of BPQ within each group. They showed no relationship with either clinical or parasitological parameters following treatment. 相似文献
10.
Gachohi John M. Kitala Phillip M. Ngumi Priscilla N. Skilton Rob A. 《Tropical animal health and production》2011,43(1):271-277
The objective of this study was to investigate the relationship between seroprevalence to Theileria parva infection in cattle and potential environmental and farm-level effects in 80 farms under traditional crop–livestock system
in Mbeere District, Kenya. A standardized questionnaire was used to collect the effects characteristics as related to T. parva infection epidemiology. Serum samples were collected from 440 cattle of all ages for detection of T. parva antibodies by the enzyme-linked immunosorbent assay technique. The association between the variables was assessed using a
generalized estimation equation logistic regression model. The overall T. parva seroprevalence, accounting for correlation of responses, was 19.3% (95% confidence interval (CI) 14%, 25%). Two variables,
“administrative division” and “presence of the vector tick on the farm”, were significantly associated with the T. parva seroresponse. Respectively, cattle from farms in Gachoka, Evurore, and Mwea divisions were (and their 95% CI) 1.3 (0.36,
4.8), 4.4 (1.2, 15.9), and 15.2 (4.9, 47.1) times more likely to be seropositive relative to those from Siakago Division (P = 0.000). Cattle from farms in which the vector tick was present were 2.9 (1.2, 6.7) times more likely to be seropositive
(P = 0.011). Results of this study suggested that both environmental and farm factors may be associated with T. parva infection epidemiology in Mbeere District. Under such circumstances, characterization of environmental suitability for the
vector tick and corresponding environment-specific farm management practices in the district is required both for improved
understanding of the disease and in planning disease control programs. 相似文献
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