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Bishop R Geysen D Spooner P Skilton R Nene V Dolan T Morzaria S 《Veterinary parasitology》2001,94(4):227-237
The 'Muguga cocktail' which is composed of three Theileria parva stocks Muguga, Kiambu 5 and Serengeti-transformed has been used extensively for live vaccination against East Coast fever in cattle in eastern, central and southern Africa. Herein we describe the molecular characterisation of the T. parva vaccine stocks using three techniques, an indirect fluorescent antibody test with a panel of anti-schizont monoclonal antibodies (MAb), Southern blotting with four T. parva repetitive DNA probes and polymerase chain reaction (PCR)-based assays detecting polymorphism within four single copy loci encoding antigen genes. The Muguga and Serengeti-transformed stocks exhibited no obvious differences in their reactivity with the panel of MAbs, whereas Kiambu 5 differed with several MAbs. Kiambu 5 DNA was very distinct from the Muguga and Serengeti-transformed isolates in the hybridisation pattern with all four nucleic acid probes, whereas Muguga and Serengeti-transformed isolates exhibited minor differences and could not be discriminated with one of the probes. PCR amplification in combination with restriction fragment length polymorphism analysis indicated that Kiambu 5 was also markedly divergent from the Muguga and Serengeti-transformed stocks within two of the four antigen coding genes. The T. parva Serengeti-transformed stock did not contain a 130 base pair insert within the p67 sporozoite antigen gene, which has been observed previously in most T. parva parasites isolated from buffalo, and could not be discriminated from T. parva Muguga at any of the four single copy loci. Collectively the data indicate that two of the cocktail components T. parva Serengeti-transformed and Muguga are genetically closely related, while the third component Kiambu 5 is quite distinct. Based on the findings, there may be a need to include only one of the T. parva Muguga and Serengeti-transformed components in the immunising cocktail. The study demonstrates the value of molecular characterisation data for monitoring of live vaccines. 相似文献
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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
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Kang&#;ethe Erastus K. Mulinge Erastus K. Skilton Robert A. Njahira Moses Monda Joseph G. Nyongesa Concepta Mbae Cecilia K. Kamwati Stanley K. 《Tropical animal health and production》2012,44(1):25-31
A total of 1,734 cattle faecal samples from 296 dairy-keeping households were collected from urban settings in Nairobi, Kenya. Modified Ziehl–Neelsen staining method and an immunofluorescence assay were used to identify those samples with Cryptosporidium oocyst infection. Oocysts from positive faecal samples were isolated by Sheather's sucrose flotation method and picked from the concentrate using cover slips. Genomic DNA was extracted from 124 of the faecal samples that were positive for Cryptosporidium and was used as template for nested PCR of the 18S rRNA gene. Twenty-five samples (20 %) were PCR-positive for Cryptosporidium, and 24 of the PCR products were successfully cloned and sequenced. Sequence and phylogenetic analysis identified 17 samples (68 %) as Cryptosporidium parvum-like, four samples (16 %) as Cryptosporidium ryanae, three samples (12 %) as Cryptosporidium andersoni and one sample (4 %) as Cryptosporidium hominis. To the best of our knowledge, this is the first genotyping study to report C. parvum-like, C. andersoni and C. hominis in cattle from Kenya. The results of this study show Cryptosporidium infections in calves and cattle may be potential zoonotic reservoirs of the parasite that infects humans. 相似文献
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EK Kang'ethe EK Mulinge RA Skilton M Njahira JG Monda C Nyongesa CK Mbae SK Kamwati 《Tropical animal health and production》2012,44(Z1):25-31
A total of 1,734 cattle faecal samples from 296 dairy-keeping households were collected from urban settings in Nairobi, Kenya. Modified Ziehl-Neelsen staining method and an immunofluorescence assay were used to identify those samples with Cryptosporidium oocyst infection. Oocysts from positive faecal samples were isolated by Sheather's sucrose flotation method and picked from the concentrate using cover slips. Genomic DNA was extracted from 124 of the faecal samples that were positive for Cryptosporidium and was used as template for nested PCR of the 18S rRNA gene. Twenty-five samples (20?%) were PCR-positive for Cryptosporidium, and 24 of the PCR products were successfully cloned and sequenced. Sequence and phylogenetic analysis identified 17 samples (68?%) as Cryptosporidium parvum-like, four samples (16?%) as Cryptosporidium ryanae, three samples (12?%) as Cryptosporidium andersoni and one sample (4?%) as Cryptosporidium hominis. To the best of our knowledge, this is the first genotyping study to report C. parvum-like, C. andersoni and C. hominis in cattle from Kenya. The results of this study show Cryptosporidium infections in calves and cattle may be potential zoonotic reservoirs of the parasite that infects humans. 相似文献
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Agroforestry Systems - The issues of biological and genetic diversity management in agroforestry are extremely complex. This paper focuses on genetic diversity management and its implications for... 相似文献
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Onyango Irene Awino Robert Skilton Shadrack Muya Samuel Kabochi Hellen Kutima Muo Kasina 《East African Agricultural and Forestry Journal》2017,82(1):23-35
Varroa mite (Varroa destructor Anderson and Trueman) is a major global threat to the western honey bee (Apis mellifera L.). The ectoparasite has been implicated in the spread of honeybee viruses. Beekeeping plays a major role in transmission of the mite. The study aimed at assessing levels of Varroa infestation, bee viruses and bacteria incidences in domesticated honeybee colonies. Samples of adult honey bees, bee brood and Varroa mites were collected from Baringo, Narok, Kwale, Magarini, Voi, Ijara, Busia and Siaya in Kenya. Ten hives in each site were inspected for the presence of Varroa mites on adult bees using the icing sugar technique and forceps in sealed brood cells. The number of mites observed were recorded per site. Ribonucleic acid was extracted from the mites, brood and adult bees and a polymerase chain reaction was performed to detect the black queen cell virus. Pooled RNA samples of brood and adult bees were used in next generation sequencing on a 454 GS FLX platform to detect bee viruses and bacteria. Varroa mites were reported in all the study sites at varying levels. The black queen cell virus and three iflaviruses, European foul brood and its secondary causative agent Enterococcus faecalis were reported. The Kenyan honeybee population is threatened by bee pests and pathogens. There is a need for constant monitoring of bee pests and diseases in honeybee colonies in the country for early detection and to provide data on the status of bee health. All stakeholders in the beekeeping value chain should be enlightened on their role in pest and disease transmission. 相似文献
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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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* The working group was set up by the Veterinary Products Committee in response to current concern in both the public domain and in the scientific community about possible health risks related to the routine vaccination of cats and dogs. The working group concluded that vaccination plays a very valuable role in the prevention and control of the major infectious diseases in cats and dogs. Although adverse reactions to vaccination, including lack of efficacy, occasionally occur, the working group concluded that the overall risk/benefit analysis strongly supports their continued use. * Although for some diseases there is evidence of a longer duration of immunity following vaccination than the one year which is typically recommended on the product literature, there is currently insufficient information to propose revaccination intervals other than those proposed by the manufacturer and approved by the regulatory process. * Notwithstanding this, in view of the occasional occurrence of adverse reactions, the working group recommends that the product literature indicates that the regime for booster vaccinations is based on a minimum duration of immunity rather than a maximum. The working group further recommends that the product literature should state that a risk/benefit assessment should be made for each individual animal by the veterinary surgeon in consultation with the owner with respect to the necessity for each vaccine and the frequency of its use. * The evidence suggests that cats appear to be susceptible to the occasional development of sarcomas at sites of injection and there is some further evidence to suggest that, although other products may be involved, this may be more associated with the use of vaccines containing aluminium-based adjuvants. The working group therefore recommends that a generic warning to this effect should appear on the product literature for all feline vaccines administered by injection. The working group also highlighted the need for professional and educational bodies in the UK to bring to the attention of veterinary practitioners appropriate methods for prevention, diagnosis and treatment of this serious condition. * The working group considered in depth the monitoring of adverse reactions, including the advantages and disadvantages of surveillance schemes. A range of options for carrying out further epidemiological (analytical) studies was also considered. However, the working group emphasised that surveillance schemes, and the UK Veterinary Medicines Directorate (VMD) Suspected Adverse Reaction (SAR) Surveillance Scheme in particular, provided a very valuable resource. The large database within the VMD scheme (collected since 1985) was analysed as part of this report. Figures were derived in terms of incidence (reporting rate) of certain clinical signs per 10,000 doses, and risk factors as identified by statistical analysis. However, due to a number of constraints, the analysis was not fully comprehensive and the interaction of possible risk factors was not determined. * Product-related control charts were developed in order to detect changes in incidence rates of adverse reactions (per 10,000 doses sold) both within and between different vaccines. Such charts provide a powerful way to detect changing trends in incidence and, when used in conjunction with product characteristics, they may identify possible causes. In general, the data showed that the incidence of adverse reactions to cat and dog vaccines per 10,000 doses of product sold was relatively low. Although under-reporting is a feature of such surveillance schemes, it does appear that, overall, vaccination of cats and dogs should be considered safe and effective. * Finally, the working group was conscious, while preparing this report, of the extensive media coverage that has been given to the issue of the safety of human vaccines, in particular the mumps, measles and rubella (MMR) vaccine. The working group emphasises that the conclusions and recommendations included in this report relate only to the vaccines used in cats and dogs. The issues identified are specific to the diseases and species examined and no attempt should be made to draw analogous conclusions in relation to vaccines administered to humans. 相似文献