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1.
OBJECTIVE: To estimate sensitivity and specificity of 4 commonly used brucellosis screening tests in cattle and domestic water buffalo of Trinidad, and to compare test parameter estimates between cattle and water buffalo. ANIMALS: 391 cattle and 381 water buffalo. PROCEDURE: 4 Brucella-infected herds (2 cattle and 2 water buffalo) and 4 herds (2 of each species) considered to be brucellosis-free were selected. A minimum of 100 animals, or all animals > 1 year of age, were tested from each herd. Serum samples were evaluated for Brucella-specific antibodies by use of standard plate agglutination test (SPAT), card test (CT), buffered plate agglutination test (BPAT), and standard tube agglutination test (STAT). A Bayesian approach was used to estimate sensitivity and specificity of diagnostic tests without the use of a gold standard, assuming conditional independence of tests. RESULTS: Sensitivity and specificity estimates in cattle, respectively, were SPAT, 66.7 and 98.9; CT, 72.7 and 99.6; BPAT, 88.1 and 98.1; and STAT, 80.2 and 99.3. Corresponding test estimates in water buffalo, respectively, were SPAT, 51.4 and 99.3; CT, 90.4 and 99.4; BPAT, 96.3 and 90.7; and STAT, 75.0 and 98.8. Sensitivity of the CT and specificity of the BPAT were different between cattle and water buffalo with at least 95% probability. CONCLUSIONS AND CLINICAL RELEVANCE: Brucellosis serologic test performance varied by species tested, but BPAT had the highest sensitivity for screening cattle and water buffalo. Sensitivity and specificity of more than 2 screening tests can be estimated simultaneously without a gold standard by use of Bayesian techniques.  相似文献   

2.
Malignant catarrhal fever (MCF) is a mostly fatal lymphoproliferative disease of cattle. In 1995 a PCR based method was introduced for the detection of the ovine herpesvirus 2 (OvHV-2), which is regarded as the causative agent of the sheep-associated form of the disease. This PCR can be regarded as a gold standard for the in vivo diagnosis of sheep-associated MCF in cattle (Müller-Doblies et al., 1998). This semi-nested PCR was now used as a reference test for the reassessment of diagnostic criteria in the clinical and post mortem diagnosis that could previously not be quantitated. Based on 83 suspected cases with a complete clinical record the clinical signs were weighted and grouped according to their sensitivity and specificity into lead signs indicative of MCF and frequently accompanying signs supportive for the diagnosis of MCF and general clinical signs that were less reliable for the diagnosis. Differential diagnoses are discussed, which are of particular significance due to their status as OIE list A diseases e.g. foot-and-mouth disease or rinderpest. 38 PCR confirmed cattle with MCF served for the quantitative analysis of organ lesions. For the post mortem diagnosis an essential set of organ samples is defined to permit a reliable histological diagnosis, as the gross pathology often did not give any indication for the diagnosis. These criteria should help to improve the diagnostic efficiency and to select the appropriate laboratory diagnostic procedures for MCF-suspected cattle.  相似文献   

3.
Most researchers in South Africa found that although BT virus could be isolated from apparently healthy cattle and from inoculated cattle the virus did not produce overt clinical disease in cattle. However, when epizootics were reported outside Africa, clinical signs were observed in cattle in Israel, Palestine, Syria, Portugal, and Spain. Most natural BT infections in cattle in the United States do not result in overt clinical signs. However, in certain infected herds, approximately 5% of the cattle show from mild to severe disease. Except for severe cases, spontaneous recovery is usual. The clinical diagnosis of BT in cattle is difficult and requires laboratory assistance. Culicoides variipennis can serve as a vector of BT virus from cattle to cattle, cattle to sheep, sheep to cattle, and sheep to sheep. In utero transmission occurs in cattle and can result in abortion, hydraencephaly, congenital deformity, and birth of viraemic calves which may or may not develop BT antibody. Calves inoculated in utero or those born to infected dams may have a persistent viraemia with or without BT antibody. tone such animal has been held in insect-secure quarters and has continued to harbour virus for 3 years. Bluetongue virus was isolated from the semen of experimentally infected bulls. Calves inoculated with BT virus and also given an immuno-suppressant developed marked clinical disease in 8 to 12 days. Bluetongue virus is very closely associated with the erythrocytes of infected cattle, sheep, and goats. Cattle are considered important and relatively long-term virus reservoirs. In attempts to determine the maximum period of viraemia in cattle it is necessary to inoculate washed erythrocytes, rather than whole blood, and to use susceptible sheep as the assay system rather than embryonated chicken eggs.  相似文献   

4.
All cattle of United Kingdom origin imported to Sweden since 1980 were traced (n=94) and the probability that none of these imported cattle had clinical signs of bovine spongiform encephalopathy (BSE) at the year of slaughter (death) was calculated. If BSE had been introduced by live-animal imports, the consequences of such an event also was evaluated. The potential of the recently introduced surveillance system of high-risk cattle to detect such an event also was evaluated.We found that BSE most probably has not been introduced to Sweden by live-animal imports. We also found that, if this event had occurred and assuming a worst-case scenario that the animal was not prevented from being rendered, the rendering system (during certain periods) would not have prevented further spread of infection. Finally, we found that the BSE surveillance of high-risk cattle has not been in place long enough to verify that this event has not occurred (as of December 2001).  相似文献   

5.
Traditionally, the planning of surveys (in particular, sample-size calculations) has relied on assumptions including the assumption of perfect screening tests. This paper presents a novel approach that can be used for planning animal-health surveys and interpreting screening-test results in the context of these surveys. A stochastic simulation model developed to assess the properties of herd-level sampling schemes and surveys has been adapted for large surveys aimed at substantiating freedom from infection at a national or regional level. We use a Bayesian approach to derive the post-survey probability of freedom from infection from the pre-survey probability of freedom and the likelihood ratio that is associated with screening-test results. We applied the model to two consecutive surveys conducted in 1998 and 1999 in Switzerland to substantiate freedom from infectious bovine rhinotracheitis (IBR) in the cattle population of about 56000 herds (median herd size of 15 cattle > 2 yr of age in 1999). In 1998, serum samples were taken from five cattle > 2 yr in 4672 herds, and in 1999 from all cattle > 2 yr old in 648 herds; samples were analysed by ELISA. The survey of 1999 provided less evidence than that of 1998 to support a status of freedom from infection; also, the characteristics of both herd-level sampling schemes were similar. We argue that the rationale for survey planning depends on the pre-survey probability of freedom from infection (i.e. our level of confidence that the infection does not occur in the targeted animal population). In consequence, surveys should be tailored to individual populations in the respective countries or regions. The model has been developed in an Excel spreadsheet to allow flexibility of use, and adaptation to many other animal-health issues.  相似文献   

6.
A complete search of the literature concerning Lyme borreliosis as it relates to horses and cattle was done. The epidemiology, pathogenesis, immunological response to the disease, diagnosis and treatment are discussed. A review of clinical cases in horses and cattle is presented. Clinical signs of Lyme borreliosis in horses include: chronic weight loss, sporadic lameness, laminitis, low grade fever, swollen joints, muscle tenderness, and anterior uveitis. In addition to those clinical signs, neurological signs such as depression, behavioral changes, dysphagia, head tilt and encephalitis can be seen in chronic cases. Borreliosis occurs in cattle, usually as a herd problem. In acute Lyme borreliosis, cattle often will show a fever, stiffness, swollen joints, and decreased milk production. Chronic weight loss, laminitis and abortion are also possible outcomes of borreliosis in cattle. Diagnosis of clinical Lyme borreliosis is difficult and depends upon recognition of clinical signs, a history of possible exposure, and identification of the spirochete in the affected animal. Since the spirochete is very difficult to culture, confirmation of B. burgdorferi infection often relies on serologic testing. Subclinical seropositive animals do occur, thus confusing the diagnosis. An approach to treatment of cattle and horses with Lyme borreliosis is outlined.  相似文献   

7.
The two key aims of this research were: (i) to conduct a probabilistic elicitation to quantify the variation in veterinarians' beliefs regarding the efficacy of systemic antibiotics when used as an adjunct to intra-mammary dry cow therapy and (ii) to investigate (in a Bayesian statistical framework) the strength of future research evidence required (in theory) to change the beliefs of practising veterinary surgeons regarding the efficacy of systemic antibiotics, given their current clinical beliefs. The beliefs of 24 veterinarians in 5 practices in England were quantified as probability density functions. Classic multidimensional scaling revealed major variations in beliefs both within and between veterinary practices which included: confident optimism, confident pessimism and considerable uncertainty. Of the 9 veterinarians interviewed holding further cattle qualifications, 6 shared a confidently pessimistic belief in the efficacy of systemic therapy and whilst 2 were more optimistic, they were also more uncertain. A Bayesian model based on a synthetic dataset from a randomised clinical trial (showing no benefit with systemic therapy) predicted how each of the 24 veterinarians' prior beliefs would alter as the size of the clinical trial increased, assuming that practitioners would update their beliefs rationally in accordance with Bayes' theorem. The study demonstrated the usefulness of probabilistic elicitation for evaluating the diversity and strength of practitioners' beliefs. The major variation in beliefs observed raises interest in the veterinary profession's approach to prescribing essential medicines. Results illustrate the importance of eliciting prior beliefs when designing clinical trials in order to increase the chance that trial data are of sufficient strength to alter the clinical beliefs of practitioners and do not merely serve to satisfy researchers.  相似文献   

8.
Vector-borne diseases pose a special challenge to veterinary authorities due to complex and time-consuming surveillance programs taking into account vector habitat. Using stochastic scenario tree modelling, each possible surveillance activity of a future surveillance system can be evaluated with regard to its sensitivity and the expected cost. The overall sensitivity of various potential surveillance systems, composed of different combinations of surveillance activities, is calculated and the proposed surveillance system is optimized with respect to the considered surveillance activities, the sensitivity and the cost. The objective of this project was to use stochastic scenario tree modelling in combination with a simple cost analysis in order to develop the national surveillance system for Bluetongue in Switzerland. This surveillance system was established due to the emerging outbreak of Bluetongue virus serotype 8 (BTV-8) in Northern Europe in 2006. Based on the modelling results, it was decided to implement an improved passive clinical surveillance in cattle and sheep through campaigns in order to increase disease awareness alongside a targeted bulk milk testing strategy in 200 dairy cattle herds located in high-risk areas. The estimated median probability of detection of cases (i.e. sensitivity) of the surveillance system in this combined approach was 96.4%. The evaluation of the prospective national surveillance system predicted that passive clinical surveillance in cattle would provide the highest probability to detect BTV-8 infected animals, followed by passive clinical surveillance in sheep and bulk milk testing of 200 dairy cattle farms in high-risk areas. This approach is also applicable in other countries and to other epidemic diseases.  相似文献   

9.
Mycoplasma bovis is a pathogen causing respiratory disease, otitis media, arthritis, mastitis, and a variety of other diseases in cattle worldwide. It is increasingly recognized by the veterinary and livestock communities as having an important impact on the health, welfare, and productivity of dairy and beef cattle. M. bovis diseases can be difficult to diagnose and control because of inconsistent disease expression and response to treatments and vaccines, and large gaps in our understanding of the epidemiology and pathophysiology of these diseases. There are limited data on which to base evidence-based decisions for treatment and control, and the literature contains differing clinical biases and opinions. This document is intended for veterinarians dealing with cattle and is focused on the cattle production systems of North America. The goal of the consensus statement panel was to encourage an evidence-based approach to M. bovis problems. The scientific literature was critically reviewed, including peer-reviewed journal articles and reviews obtained by database searches using the terms "Mycoplasma bovis" or "mycoplasma + cattle." Where other data were lacking, conference proceedings were reviewed as a source of expert opinion.  相似文献   

10.
Mycoplasma species have a global distribution causing serious diseases in cattle worldwide including mastitis, arthritis, pneumonia, otitis media and reproductive disorders. Mycoplasma species are typically highly contagious, are capable of causing severe disease, and are difficult infections to resolve requiring rapid and accurate diagnosis to prevent and control disease outbreaks. This review discusses the development and use of different diagnostic methods to identify Mycoplasma species relevant to cattle, with a particular focus on Mycoplasma bovis. Traditionally, the identification and diagnosis of mycoplasma has been performed via microbial culture. More recently, the use of polymerase chain reaction to detect Mycoplasma species from various bovine samples has increased. Polymerase chain reaction has a higher efficiency, specificity, and sensitivity for laboratory diagnosis when compared with conventional culture‐based methods. Several tools are now available for typing Mycoplasma spp. isolates, allowing for genetic characterization in disease outbreak investigations. Serological diagnosis through the use of indirect ELISA allows the detection of antimycoplasma antibodies in sera and milk, with their use demonstrated on individual animal samples as well as BTM samples. While each testing method has strengths and limitations, their combined use provides complementary information, which when interpreted in conjunction with clinical signs and herd history, facilitates pathogen detection, and characterization of the disease status of cattle populations.  相似文献   

11.
Bovine babesiosis is a tick-borne disease caused by Babesia spp. haemoprotozoans. The disease is of great importance at tick enzootic unstable areas and hampers cattle production in several developing countries. The available immunisation alternatives are pre-immunition and attenuated vaccines. Despite being efficient and protective, they are unsafe as they use cattle blood cells as inoculum and may potentially spread other diseases. Another alternative to help in babesiosis control would be the identification of genetically resistant cattle to Babesia bovis infection. The objective of this work was to phenotype cattle based on primary response against B. bovis infection. Two-hundred and forty half-sib Hereford and Aberdeen Angus heifers (120 animals from each breed), 12-18-month-old na?ve cattle, originated from a tick-free area in Southern Brazil, were used in the experiment. Animals were monitored following an inoculation with 1x10(7)B. bovis parasitised erythrocytes. Results showed three different phenotypes: 1-'susceptible', animals with babesiosis clinical signs that received treatment to avoid death; 2-'intermediate', animals with clinical signs: parasitaemia, >or=21.5% reduction in packed cell volume (PCV) and increase in body temperature when compared to their pre-challenge physiological parameters, no specific treatment was needed as animals self recovered from the disease, and 3-'resistant', animals without clinical signs that showed B. bovis presence in blood smears, <21.5% PCV reductions, with little or no increase in body temperature and no need for babesiosis treatment. The frequencies of each phenotype were: 45.4, 26.7, and 27.9%, respectively, demonstrating the existence of phenotypic variation for B. bovis in Bos taurus cattle.  相似文献   

12.
Background: Cerebrospinal fluid (CSF) analysis is routinely used to aid in the diagnosis of central nervous system (CNS) disease in animals. There is little comprehensive information available on the diagnostic utility of CSF analysis in cattle. Objectives: The purpose of this retrospective study was to review the characteristic CSF findings of specific CNS diseases in cattle. Methods: Medical records of cattle in which CSF analysis had been performed between 1990 and 2008 were reviewed. Cattle were included in the study if they had a confirmed diagnosis of CNS disease (based on clinical signs, laboratory testing, and/or histopathologic results). Cattle were categorized as having infectious or noninfectious causes of CNS disease and subgrouped based on specific disease diagnosis. CSF results were summarized and compared using nonparametric statistical tests. Results: Data from 102 cattle, mostly female Holsteins, were included in the study. Bacterial infections, particularly listeriosis and neonatal meningitis, were the most common cause of CNS disease. Neonatal meningitis was characterized by a marked, predominantly neutrophilic, pleocytosis. Mild mononuclear pleocytosis was typical of listeriosis, but was also seen with abscesses, viral infections, salt poisoning, and trauma. Variable CSF results were seen in cattle with otitis‐related meningitis and thromboembolic meningoencephalitis. CSF results were usually normal with toxic, metabolic, degenerative, and neoplastic disorders. Conclusions: CSF analysis is a useful adjunctive test for the diagnosis of CNS diseases in cattle. When interpreted together with signalment and clinical signs, CSF results can assist clinicians in the antemortem diagnosis of specific bovine CNS disorders.  相似文献   

13.
The cytokines of bovine mammary gland: prospects for diagnosis and therapy   总被引：5，自引：0，他引：5  
The lack of efficacy of conventional strategies for the maintenance of healthy udders in domestic cattle has prompted studies on the use of cytokines for this purpose. The adjuvant use of recombinant bovine cytokines, such as IL-2, IFN-gamma and TNF-alpha, in normal mammary gland, mobilizes innate and acquired immunity. However, stimulated immunity does not prevent or eradicate infection, particularly in the case of Staphylococcus aureus mastitis. Cytokines do, however, improve the bactericidal efficiency of certain antibiotics. The subtle and sensitive changes in the cytokine network of normal and mastitic bovine mammary gland may encourage the use of cytokines in the diagnosis and prognosis of udder health. Numerous studies support this hypothesis, and detection and monitoring of cytokines could become an important alternative management for udder health. The use of cytokines in the immunotherapy, diagnosis and prognosis of mastitis will grow with knowledge of the cytokine network in bovine mammary glands and the development of efficient cytokine diagnostic techniques.  相似文献   

14.
Identifying spatial patterns of risk is important in the study of diseases with ecologic causes. Furthermore, relatively complex hierarchical modeling is required to determine how factors that are organized across levels interact, such as how an ecologic cause interacts with farm management and with animal characteristics. The objective of this study was to map the risk for Mycobacterium avium subspecies paratuberculosis (MAP - the causative agent of Johne's disease) and Neospora caninum (NC - the cause of neosporosis) infections in Alberta beef and dairy cattle. This objective utilized Bayesian generalized linear kriging to partition herd effects into a portion attributable to location and a portion that was independent of location. Seropositivity to NC in beef cattle showed strong support for spatial covariance, suggesting that ecologic causes were important for beef cattle but not dairy cattle. There was little evidence of spatial covariance for MAP seropositivity in either beef or dairy cattle.  相似文献   

15.
Infection of cattle with bovine viral diarrhoea virus (BVD virus) is common throughout the world(1) and the prevalence of neutralising antibodies to the virus reported from surveys ranges from about 40% to 90%(2)(3)(4). The first isolation of BVD virus in New Zealand was reported in 1967(5) and, since that time, evidence of widespread infection in dairy cattle has been presented(6). Whilst the diseases associated with BVD viral infection have been well recognised in dairy herds, there has been a belief that infection of beef herds is less common. Based on this belief has been the fear that the growth of the dairy beef industry could lead to the introduction of BVD virus into an essentially naive beef population with disastrous results such as those reported by MacNeil and van der Oord(7). We decided therefore to sample beef cattle submitted to abattoirs throughout New Zealand for serological evidence of prior exposure to BVD virus.  相似文献   

16.
为普及家蚕病害的基础知识,辅助提高蚕病诊断的准确率和蚕病防治技术水平,采用微软成熟的IIS+ASP+ACCESS技术建立了基于Internet的包含19种主要家蚕病害在内的诊断与防治专家系统(http:∥211.90.162.131:8099/)。该系统包括蚕病基本知识、识别与诊断知识、发病规律与防治知识、辅助诊断系统以及咨询与影像系统。计算机模糊判断法是辅助诊断系统的核心模块,该模块通过将专家经验转化为可供计算的模式概率值,建立数据库,即可从已知的病征(事实、证据)出发,采用模糊产生式诊断规则给出模糊断言的最大值作为诊断结果,并自动提出相应的防治措施。  相似文献   

17.
Frequently occurring diseases are discussed in 2- to 12-month-old pastured or feedlot cattle. Emphasis is on gross necropsy lesions that are significant in differential diagnosis. Where applicable, practical laboratory tests that are helpful in confirming a diagnosis are described. Information about proper selection and preservation of tissues for submission to a diagnostic laboratory is included.  相似文献   

18.
Theileria parva is the causative agent of a lethal tick-borne disease of cattle occurring in eastern, central and southern Africa. Variations in the sensitivity of the serological and molecular tests with seasonal vector occurrence and discrepancies between low PCR prevalence and high T. parva vector density are a setback to estimate true prevalences. Therefore, the objectives of the present studies were to evaluate (1) the sensitivity of three serological tests (IFAT, ELISA and SELISA) and one molecular test (PCR) in the diagnosis of chronic T. parva infections in four different agro-ecological zones of Rwanda and (2) the effect of tick challenge and animal's age on the sensitivity of PCR. Blood samples from 635 bovines were collected in four agro-ecological zones of Rwanda. All sera were screened using the IFAT, ELISA, SELISA and PCR. The binary results of the four diagnostic tests were introduced separately for each agro-ecological zone in a Bayesian model to estimate the prevalence of T. parva infections and the sensitivity of the four diagnostic tests. All test specificities were set to 100%. The estimated T. parva prevalence was much higher (83–85%) than estimations based on single diagnostic tests. The estimated sensitivity of serological tests was relatively constant and ranged from 57 to 75% in the various areas. The sensitivity of PCR showed more pronounced variations, ranging from 66% in the low T. parva transmission (high land) zones compared to 24% in the highly vector infested (low land) zones. Calves and adult cattle (n = 194) were also sampled in regularly and irregularly dipped herds in the low land region. The apparent T. parva prevalence detected by PCR was significantly higher in calves than in adult cattle and in herds regularly treated with acaricides, while no significant differences were found with IFAT. The conditional probability that a sample was positive at PCR while it was positive at IFAT was significantly lower in adults. The implication of these findings in the use of diagnostic assays for epidemiological studies is discussed.  相似文献   

19.
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20.
The medical records of 220 dogs with inflammatory/infectious diseases of the central nervous system (CNS) were retrospectively examined. The aims of the study were to determine if clinical and clinicopathologic data (not including biopsy or necropsy examination) could distinguish inflammatory CNS diseases from diseases of other types, and to search for criteria allowing differentiation of specific inflammatory diseases. The signalment, historical findings, extraneural and neurological signs, and the lesion site contributed marginally to a specific diagnosis. Multifocal signs were only noticed in one third of the dogs with inflammatory/infectious diseases. Particular neurological abnormalities were more frequent in certain diseases than in others (eg, myoclonus was frequent in dogs with distemper, but it was also found in those with other meningoencephalomyelitides). Hematologic findings contributed to the diagnosis in certain conditions (eg, canine distemper encephalitis, protozoal encephalomyelitis, steroid-responsive meningitis-arteritis). Cerebrospinal fluid examinations, including immunoglobulin G index and cytology were useful to separate meningoencephalomyelitides from the other CNS diseases and to distinguish certain conditions from others. In most cases a specific diagnosis depended on a combination of clinical signs and ancillary diagnostic aids. Still, a specific diagnosis remained very difficult, if not impossible, in at least one third of the dogs.  相似文献   

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