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1.
A diagnostic project was initiated across the United States in 2006 to improve the understanding of porcine circovirus associated diseases (PCVAD) as well as to identify co-factors in PCVAD-affected farms. A Porcine circovirus-2 (PCV-2) DNA real-time polymerase chain reaction quantitation (qPCR) was established according to a published method and sera from a total of 23pig farms across the United States were examined for viral loads for PCV-2 and analyzed for any possible effects of Porcine reproductive and respiratory syndrome virus (PRRSV) vaccination on this parameter. Vaccination against PRRS resulted in significantly lower viral loads for PCV-2 in animals 13 wk or older compared with nonvaccinated animals, but vaccination of pigs against PRRS had no effect on qPCR results for PCV-2 in 4- to 12-week-old pigs. Interestingly, PRRS vaccinates had significantly lower viral loads when peak wasting disease was observed in the herds. The qPCR method for PCV-2 proved to be an important tool for help in the antemortem diagnosis of PCVAD as well as in the monitoring of infection dynamics.  相似文献   

2.
Porcine circovirus type 2 (PCV2) belongs to the viral family Circoviridae and to the genus Circovirus . Circoviruses are small, single-stranded nonenveloped DNA viruses that have an unsegmented circular genome. PCV2 is the primary causative agent of several syndromes collectively known as porcine circovirus-associated disease (PCVAD). Many of the syndromes associated with PCVAD are a result of coinfection with PCV2 virus and other agents such as Mycoplasma and porcine reproductive and respiratory syndrome virus. PCV2 infection is present in every major swine-producing country in the world, and the number of identified cases of PCVAD is rapidly increasing. In the United States, the disease has cost producers an average of 3–4 dollars per pig with peak losses ranging up to 20 dollars per pig. The importance of this disease has stimulated investigations aimed at identifying risk factors associated with infection and minimizing these risks through modified management practices and development of vaccination strategies. This paper provides an overview of current knowledge relating to PCV2 and PCVAD with an emphasis on information relevant to the swine veterinarian.  相似文献   

3.
Porcine circovirus associated disease (PCVAD) is currently one of the most economically important diseases in the global swine industry. Porcine circovirus type 2 (PCV2) is the primary causative agent, however co-infection with other swine pathogens such as porcine reproductive and respiratory syndrome virus (PRRSV) is often required to induce the full spectrum of clinical PCVAD. While the specific mechanisms of viral co-infection that lead to clinical disease are not fully understood, immune modulation by the co-infecting viruses likely plays a critical role. We evaluated the ability of dendritic cells (DC) infected with PRRSV, PCV2, or both to induce regulatory T cells (T(regs)) in vitro. DCs infected with PCV2 significantly increased CD4(+)CD25(+)FoxP3(+) T(regs) (p<0.05) and DCs co-infected with PRRSV and PCV2 induced significantly higher numbers of T(regs) than with PCV2 alone (p<0.05). Cytokine analysis indicated that the induction of T(regs) by co-infected DCs may be dependent on TGF-β and not IL-10. Our data support the immunomodulatory role of PCV2/PRRSV co-infection in the pathogenesis of PCVAD, specifically via T(reg)-mediated immunosuppression.  相似文献   

4.
Porcine circovirus type 2 (PCV2) infection is distributed worldwide and PCV2-associated disease (PCVAD) is considered among the most economically relevant ones to the global swine industry. PCV2 is known to play a causal role in the porcine respiratory disease complex, usually in close association with a large plethora of other biologic agents. We describe herein a case of fatal parasitic bronchopneumonia by Metastrongylus elongatus in a PCV2-infected pig. Metastrongylosis may still represent a major concern for outdoor herds. Our recent experience suggests that a concurrent PCVAD condition may trigger metastrongylosis, which may subsequently result, at its turn, in severe, sometimes fatal, pulmonary disease.  相似文献   

5.
OBJECTIVE: To evaluate the epidemiologic efficacy and economic efficiency of current and potential future control programs for paratuberculosis (Johne's disease) on midsize dairy herds in the United States. DESIGN: Stochastic dynamic computer simulation model. SAMPLE POPULATION: Data on prices and other input variables collected from various sources were used to represent a population of midsize US dairy herds infected with paratuberculosis. PROCEDURE: The simulation model was modified to reflect management and production characteristics of midsize dairy herds in the United States. The model was validated by use of field data and expert opinion. Various control strategies then were simulated and compared on an epidemiologic basis and on the basis of economic efficiency. RESULTS: Test-and-cull strategies and vaccination against paratuberculosis were not able to decrease the mean prevalence of disease in the United States. Typically, only vaccination was economically attractive. Improved management strategies decreased the prevalence of paratuberculosis considerably and had high economic benefits. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of results of this study suggests that test-and-cull strategies alone do not reduce the prevalence of paratuberculosis in cattle and are costly for producers to pursue. Vaccination did not reduce the prevalence but was economically attractive. Finally, improved calf-hygiene strategies were found to be critically important in every paratuberculosis control program and most were economically attractive programs for midsize US dairy farms with the disease.  相似文献   

6.
Emergency management consists of 4 components—mitigation, preparedness, response, and recovery. All 4 are necessary for an effective plan to address the next bioterrorist attack, emerging infectious disease, or foreign animal disease that may compromise our animal populations. Emergency management plans developed at the local level must coordinate with such plans at the state level, which then should ultimately coordinate at the federal level. Because the equine industry is such an economically important one in the United States, it is particularly susceptible to the devastating repercussions of natural and contrived disasters. It is essential that veterinarians remain vigilant in detecting emerging infectious or foreign animal disease events, be informed about how to contact the state and federal authorities to report their suspicions, and assist their clients with any emergency management strategies, so as to minimize losses.  相似文献   

7.
Part I of this 2-part review examined the clinical stages, pathophysiology, diagnosis, and epidemiology of Johne's disease, providing information relevant to Canada, where available. In Part II, a critical review of the economic impacts of the disease, risk factors, and important control measures are presented to enable Canadian bovine practitioners to successfully implement control strategies and participate in control programs. In cattle positive by enzyme-linked immunosorbant assay, there is a 2.4 times increase in the risk of their being culled, and their lactational 305-day milk production is decreased by at least 370 kg. Reduced slaughter value and premature culling account for losses of CDN dollars 1330 per year per infected 50-cow herd. Research has failed to show a consistent association between Mycobacterium avium subsp. paratuberculosis test status and reduced fertility or risk of clinical or subclinical mastitis. Host level factors include age and level of exposure, along with source of exposure, such as manure, colostrum, or milk. Agent factors involve the dose of infectious agent and strains of bacteria. Environmental management factors influence the persistence of the bacteria and the level of contamination in the environment. Emphasizing a risk factor approach, various control strategies are reviewed, including a number of national control programs currently in place throughout the world, specifically Australia, The Netherlands, and the United States. By reviewing the scientific literature about Johne's disease, control of the disease could be pursued through informed implementation of rational biosecurity efforts and the strategic use of testing and culling.  相似文献   

8.
Introduction: West Nile virus (WNV) first appeared in the United States in 1999, causing illness and death in birds, horses, and humans. While the initial outbreak of this sometimes deadly viral disease was limited to the northeastern United States, the virus had an inexorable migration across the continental United States over the next 3 years, causing huge losses among the affected species. The purpose of this review is to present currently available information regarding the epi‐demiology, diagnosis, treatment, and prevention of WNV infection. Veterinarians, particularly those in an emergency practice, serve as an important source of reliable information regarding this disease for animal owners and the public in general. Data sources: Data sources used for the preparation of this review include computer‐based searches of PubMed and Commonwealth Agricultural Bureaux (CAB) abstracts. A search in PubMed using ‘West Nile’ retrieved 1468 ‘hits’ or references, while a similar search in CAB abstracts produced 815 references. Additional information was obtained from various meeting proceedings, particularly data presented in abstract form, and from the Centers for Disease Control (CDC) website dedicated to WNV. Human data synthesis: Prior to the mid‐1990s, reported large‐scale epidemics of WNV infection in humans predominantly presented as acute, mild, febrile disease, sometimes associated with lymphadenopathy and skin rash. The recent large epidemic in the United States, in contrast, has prominently featured encephalitis, particularly among the elderly. Additionally, polio‐encephalomyelitis‐like complications resulting in long‐term neurologic sequelae have been reported. There are many WNV‐permissive native avian and mosquito hosts in the Unites States and there appear to be few limitations to the spread of the disease in the United States. It is expected that the virus will be identified in all 48 continental states, Mexico, and Canada by the end of 2003. Veterinary data synthesis: The horse is the animal species most affected by the recent WNV epidemic in the United States, and losses to the equine industry have been large and unprecedented. A United States Department of Agriculture (USDA)‐approved vaccine against WNV has been in use in horses since 2001 and appears to be effective in limiting the incidence of disease in well‐vaccinated populations. WNV infection has been documented in other species of mammals, including camelids (alpaca/llamas) and dogs, and veterinarians should include WNV as a differential diagnosis for animals presenting with clinical signs consistent with central nervous system infection. A large concern exists for endangered bird populations, particularly birds of prey, whether in zoos or in the wild.  相似文献   

9.
He DS  Li KN  Lin XM  Lin SR  Su DP  Liao M 《Veterinary microbiology》2011,154(1-2):185-190
Porcine circovirus type 2 (PCV2) is a single-stranded circular DNA virus that is the causative agent of porcine circovirus associated disease (PCVAD), a disease complex affecting swine around the world. Although this virus is believed to negatively affect the host's immune system, the mechanism by which PCV2 induces disease is not completely understood. This report describes a series of PCV2 experiments using the gnotobiotic pig model in which a relationship was demonstrated between abnormal leukograms and development of clinical disease in PCV2-infected pigs. When compared to control pigs the leukogram was characterized by a decrease in lymphocytes within 14 days post inoculation (dpi) followed by an increase in neutrophils 7-14 days later. No significant changes in the circulating monocyte, basophil, and eosinophil cell populations were detected. The combination of an absolute neutrophilia and lymphopenia produced a neutrophil/lymphocyte ratio that was predictive of clinical disease and was inversely correlated with the presence of neutralizing antibodies. Based on previous reports, the lymphopenia may be attributed to a direct cytolytic effect of the virus and could negatively affect the pig's immune response. The role of the neutrophilia in the pathogenesis of PCVAD in gnotobiotic pigs is unknown.  相似文献   

10.
Abstract

In recirculation finfish facilities in the United States and Canada, biosecurity utilization is neither consistent nor uniform. Seeking reasons for this situation, we examined the beliefs, perceptions, and attitudes of managers and owners of such facilities about fish disease and biosecurity utilization. A questionnaire was mailed in the fall of 2001 to the managers and owners of 152 finfish-rearing recirculation facilities in the United States and Canada to gather information on their attitudes, beliefs, and perceptions regarding fish disease and biosecurity. The response rate to the survey was 86%. This paper reports on a subset of the overall responses, the responses of managers and owners who identified their facility as a business operation. Although respondents had a positive attitude towards biosecurity utilization, they had different beliefs about which disease types were of greatest concern for their farm. Respondents also had differing perceptions on the risk of disease transmission associated with different activities on their farms. In addition, respondents had various beliefs about the practicality and effectiveness of different biosecurity measures and why the practice of biosecurity was important to their farms. This study gives quantitative evidence that different fish farmers perceive disease and the practice of biosecurity differently. This study indicates that recognition of the human dimensions element is an important first step in the creation of biosecurity policies, strategies, and procedures that will be readily accepted and implemented and consistently applied by fish farmers on their farms. The findings challenge the heretofore traditionally accepted belief that poor biosecurity practice on a farm is primarily related to lack of knowledge about biosecurity.  相似文献   

11.
Objective To report the occurrence and pathology of porcine circovirus type 2 (PCV2)‐associated disease (PCVAD) of postweaning pigs in two Australian pig herds. Methods Mortality data from two commercial piggeries that experienced higher than normal postweaning illthrift and mortalities were examined. Gross and histopathological examinations were performed on the index cases, and at weekly intervals thereafter for a period of 10 weeks. Specimens were submitted to the laboratory for routine diagnostic testing and for exclusion of porcine reproductive and respiratory syndrome virus (PRRSV). The genomes of two strains of PCV2 isolated during testing were sequenced. Results Mortality rates in weaned, 5–12‐week‐old pigs spiked significantly during mid to late 2007. This increase in the mortalities was mainly attributed to salmonella‐associated diarrhoea and illthrift. Salmonellosis was diagnosed in 73/110 cases inclusive of both piggeries. Many pigs also had chronic granulomatous lymphadenitis and diffuse histiocytic interstitial pneumonia consistent with PCVAD and associated with varying amounts of PCV2 antigen and inclusion bodies. All samples tested for PRRSV were negative. Sequence analysis of the PCV2 isolates showed strain differences between piggeries. Conclusion This report describes the first outbreaks of PCVAD in growing pigs in Western Australia (WA) and describes lesions not previously seen in this laboratory. It also describes the first isolation of a PCV2 group 1 virus in WA associated with PCVAD. Although the outbreaks of PCVAD occurred with concurrent salmonellosis, the two diseases were unrelated. Neither of the outbreaks met the Australian case definition for the diagnosis of postweaning multisystemic wasting syndrome.  相似文献   

12.
Porcine circoviruses: a minuscule yet mammoth paradox   总被引：1，自引：0，他引：1  
Porcine circovirus type 2 (PCV2) is the primary causative agent for porcine circovirus-associated disease (PCVAD). PCVAD has been the cause of considerable economic losses to the pork industry worldwide. The disease is primarily characterized by wasting, enlarged lymph nodes, jaundice and weight loss in affected weanling pigs. Several other complex syndromes involving reproductive failure, enteritis, pneumonia and necrotizing dermatitis have also been associated with PCV2 infection. Lymphoid depletion, which is the hallmark lesion of PCVAD, predisposes the host to immunosuppression. Disease progression is further complicated by co-infections with other bacterial and viral pathogens. Despite the availability of effective vaccines for the last 2 years, newly emerging strains of the virus have been reported to cause more severe outbreaks in parts of the USA and Canada. While knowledge of the biology and pathogenesis of PCV2 has progressed considerably over the last 12 years since the disease was recognized, many questions still remain to be answered.  相似文献   

13.
猪圆环病毒2型靶细胞及其受体的研究进展   总被引：1，自引：0，他引：1  
猪圆环病毒2型(porcine circovirus type 2,PCV2)是统称为猪圆环病毒相关疾病(porcine circovirus-associated disease,PCVAD)的几个综合征的主要致病因子。目前,对PCV2配体表位和细胞受体在病毒入侵过程中的致病机理还不清楚,受体识别是病毒黏附到宿主细胞表面的第一步,在病毒入侵和致病机理方面起到重要的作用。作者对近几年来PCV2侵染的靶细胞及其靶细胞受体的研究进展作一综述。  相似文献   

14.
Contagious equine metritis (CEM) is a reportable foreign animal disease in the United States caused by the organism Taylorella equigenitalis. Import and export regulations regarding transport of horses into the United States from countries which either have a high prevalence of CEM or those that trade freely with countries having a high prevalence of CEM have failed to prevent the 2008 outbreak, which has not yet been traced to the original horse. It is important to recognize the clinical signs of acute CEM infections (endometritis, infertility, and abortion) to prevent further outbreak of disease. With early recognition, proper testing, and quarantine measures, the outbreaks and economic losses to the United States can be kept to a minimum. However, there are certain characteristics of the disease that are difficult to diagnose and control, such as the ability of the organism to infect an animal without creating clinical signs and the difficulty in culturing it. A review of the transmission, clinical signs, diagnostic methods, treatment, and prevention of CEM as well as a brief summary of the 2008 outbreak of CEM within the United States has been discussed in this article.  相似文献   

15.
Babesiosis of companion animals and man   总被引：2，自引：0，他引：2  
Babesiosis is caused by numerous organisms and is seen in a wide range of vertebrate hosts. The spectrum of disease is broad and ranges from asymptomatic carrier states to fulminant disease that results in rapid death. The importance of babesiosis in companion animals is well-recognized in parts of the world where virulent strains exist and where the diagnosis and treatment of both typical and atypical presentations is part of the everyday course of events for the small animal clinician. In parts of the world such as the United States where less virulent strains are found, diagnosis is more difficult. Diagnosis requires an astute eye examining the blood smear and a keen mind willing to "consider the zebras without forgetting the horses." Babesiosis is not uncommon in the United States; it is merely uncommonly diagnosed. The small animal clinician needs to be aware of the disease and its myriad possible presentations. A clearer understanding of the disease will lead to a truer picture of its importance not only in the United States but also worldwide.  相似文献   

16.
Tularemia     
Tularemia is a rare but potentially fatal disease that develops in numerous wild and domestic animals, including lagomorphs, rodents, cats, and humans. The disease occurs throughout much of the United States and should be considered in the differential diagnosis of acute febrile illness, particularly when risk factors such as contact with wild mammals or tick exposure are present. Veterinarians may be at increased risk of acquiring tularemia from contact with infected animals, but standard precautions should greatly reduce this risk. Outbreaks of tularemia warrant investigation, especially given the possibility of the use of F tularensis as an agent of bioterrorism.  相似文献   

17.
Anaplasma marginale (A. marginale) is a tick-borne ehrlichial pathogen of cattle that causes the disease anaplasmosis. Six major surface proteins (MSPs) have been identified on A. marginale from cattle and ticks of which three, MSP1a, MSP4 and MSP5, are from single genes and do not vary within isolates. The other three, MSP1b, MSP2 and MSP3, are from multigene families and may vary antigenically in persistently infected cattle. Several geographic isolates have been identified in the United States which differ in morphology, protein sequence and antigenic properties. An identifying characteristic of A. marginale isolates is the molecular weight of MSP1a which varies in size among isolates due to different numbers of tandemly repeated 28-29 amino acid peptides. For these studies, genes coding for A. marginale MSP1a and MSP4, msp1alpha and msp4, respectively, from nine North American isolates were sequenced for phylogenetic analysis. The phylogenetic analysis strongly supports the existence of a south-eastern clade of A. marginale comprised of Virginia and Florida isolates. Analysis of 16S rDNA fragment sequences from the A. marginale tick vector, Dermacentor variabilis, from various areas of the United States was used to evaluate possible vector-parasite co-evolution. Our phylogenetic analysis supports identity between the most parsimonious tree from the A. marginale MSP gene data and the tree that reflected the western and eastern clades of D. variabilis. These phylogenetic analyses provide information that may be important to consider when developing control strategies for anaplasmosis in the United States.  相似文献   

18.
Vesicular stomatitis.   总被引：4，自引：0，他引：4  
Vesicular stomatitis is an infrequent yet important vesicular disease of cattle, horses, and swine. Periodic outbreaks of this disease in the United States have caused economic losses in cattle herds because of decreased production, movement restrictions, and trade embargoes. Vesicular stomatitis causes clinical signs indistinguishable from those of foot-and-mouth disease. It is of utmost importance that appropriate samples are collected from clinical cases of vesicular disease in cattle and swine so a rapid laboratory diagnosis can be made.  相似文献   

19.
Feline heartworm disease is a very different clinical entity from canine heartworm disease. In cats, the arrival and death of immature heartworms in the pulmonary arteries can cause coughing and dyspnea as early as 3 months postinfection. Adult heartworms suppress the function of pulmonary intravascular macrophages and thus reduce clinical disease in chronic feline heartworm infection. Approximately 80% of asymptomatic cats self-cure. Median survival time for symptomatic cats is 1.5 years, or 4 years if only cats living beyond the day of presentation are considered. Aberrant worm migration is more frequent than it is in dogs, and sudden death can occur with no prior clinical signs. The bacterial endosymbiont Wolbachia likely contributes to the inflammatory pathology of heartworm disease, but its role is not yet fully clear. Unfortunately, the diagnosis, treatment, and management of feline heartworm disease are far from simple. Antemortem diagnosis is hampered by low worm burdens, the frequency of all-male infections, and nonspecific radiographic lesions. It is up to the veterinarian to determine the correct index of suspicion and choose the right combination of diagnostic tests to achieve an answer. Treatment is symptomatic because adulticide therapy is risky and does not increase survival time. Despite the dangers of feline heartworm disease, less than 5% of cats in the United States are on chemoprophylaxis. It is important for veterinarians to take a proactive preventive stance because heartworm infection in cats is a multisystemic disease that has no easy cure.  相似文献   

20.
Strong correlations between clinical signs on farms and the presence of lesions at slaughter have been reported. The objective of this study was to determine if changes in condemnation rates provide a data source for surveillance of disease outbreaks in pigs. The data were obtained from 1 abattoir in Ontario (2005-2007). The epidemiological relevance of the results was based on an outbreak of porcine circovirus associated disease (PCVAD) in Ontario in 2005. The total condemnations and condemnations due to arthritis and pneumonia patterns reflected the field infection of PCVAD in 2005 followed by the widespread use of porcine circovirus type 2 (PCV-2) vaccine in 2007. In contrast, increased rates of nephritis and enteritis suggested areas for enhanced surveillance for unexplained changes in disease patterns not identified through traditional passive surveillance. Further studies looking at the benefits of using abattoir data should compare condemnation patterns with multiple sources of swine health data.  相似文献   

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