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1.
牛病毒性腹泻病以发热、口腔及消化道粘膜糜烂、腹泻为主要症状,可引起怀孕母牛流产或产畸型胎儿,给养牛业造成巨大的经济损失,该病已成为当前严重危害我国养牛业的传染病之一。由于大部分感染BVDV的牛不表现特征性的临床症状和病理变化,而且引起腹泻和消化道黏膜糜烂或溃疡的疾病很多,所以确诊需进行实验室检查。目前实验室检测BVDV的主要方法是利用美国IDEXX公司ELISA诊断试剂盒,通过BVDV抗原和抗体的检测区别牛群持续感染牛。用于检测BVDV的样品种类有许多种,绝大多数是采集血液(血清)或牛奶样品进行检测。本试验对奶牛进行耳组织采样,同时采集血液和牛奶,用三种样品在相同条件下同时检测BVDV抗原,用血清和牛奶样品检测抗体,比较样品的检测结果。结果表明,这三种样品检测结果具有一致性,且耳组织采样更宜于大面积筛查。  相似文献   

2.
Research aimed at optimising diagnostic laboratory procedures is central to the development of effective bovine viral diarrhoea virus (BVDV) control programmes. BVDV is a single-stranded RNA virus that crosses the placenta to infect foetuses, resulting in reproductive losses due to foetal death or persistently infected calves that die early in life. Persistently infected animals are widely accepted to be the primary reservoir of BVDV and the largest source of infection. This poses important challenges to overall animal/herd health and can cause major losses to the cattle industry. Long-term storage of bovine ear notch samples from calves persistently infected with BVDV may adversely affect the ability of diagnostic assays to detect the virus efficiently. In order to test this hypothesis, ear notch samples from 7 animals were divided into 2 groups. One set was subjected to prompt formalin fixation and the other set stored either as fresh samples without preservatives at -2 degrees C, or soaked overnight in phosphate buffered saline followed by freezing of the supernatant fluid at -2 degrees C. Frozen ear notches and ear notch supernatant yielded positive results with an antigen-capture, enzyme linked immunosorbent assay (AC-ELISA) for the duration of the study (6 months) and optical density (OD) values remained significantly within range. There was no significant difference between storing fresh ear notch samples or PBS at -2 degrees C. However, positive immunohistochemistry (IHC) staining on formalin fixed ear notches started to fade between Day 17 and Day 29 when stored at room temperature. It was concluded that fresh ear notches could safely be stored at -2 degrees C for a period of 6 months prior to testing for BVD viral antigens.  相似文献   

3.
CASE DESCRIPTION: Severe disease and death in cows and calves affected 1 of 3 separate groups (A, B, and C) of cattle on a commercial cow-calf operation. CLINICAL FINDINGS: Clinical illness consisting of severe watery and bloody diarrhea, dehydration, weakness, and death affected adult cows and calves in 1 group (group B). Salmonella enterica serotype Newport was recovered from tissues of cows and calves from group B. TREATMENT AND OUTCOME: Despite supportive and antimicrobial treatment of cattle in group B, cow mortality rate attributable to salmonellosis in that group was 7.9% (32/407); calf mortality rate was 14.4% (52/361). None of the cows in Groups A or C died, and the calf mortality rate in those groups was low. Salmonella enterica serotype Newport was recovered from pooled fecal samples subsequently collected from each group of cows. Bovine viral diarrhea virus (BVDV) antigen was identified in an ear notch sample collected from a necropsied calf from group B. Subsequently, ear notch specimens from cattle in all 3 groups were tested for BVDV antigen. A significantly higher proportion of calves persistently infected with BVDV was identified in group B (8/295 [2.7%]), compared with the proportion in groups A and C combined (1/287 [0.3%]). CLINICAL RELEVANCE: Outbreaks of disease attributable to Salmonella Newport infection in beef cattle are unusual. Because of the immunosuppressive nature of BVDV, the possibility of animals persistently infected with BVDV within the herd should be considered during investigation of unusual outbreaks of infectious diseases.  相似文献   

4.
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5.
To reduce the cost of whole herd screening for bovine viral diarrhea virus persistently infected animals, the sensitivity and specificity of an antigen-capture enzyme-linked immunosorbent assay (AC-ELISA) and a microtiter virus isolation ELISA using saline from ear notch samples or pooled serum was determined. Pooled saline from ear notch samples, assayed by AC-ELISA, gave a sensitivity and specificity of 98% and 94%, respectively, for pools containing 2 samples and 72% and 100%, respectively, for pools of 5. The sensitivity of pooled ear notch or serum samples for bovine viral diarrhea virus detection by microtiter virus isolation (sensitivity < 5%) or serum samples for detection by AC-ELISA (sensitivity < 15%) is too low to be used for whole herd screening. Pooling saline from ear notch samples from 2 animals tested by AC-ELISA, however, could provide a less expensive, reliable method for whole herd screening for bovine viral diarrhea virus.  相似文献   

6.
OBJECTIVE: To determine whether use of serologic evaluation of a sentinel sample of calves or cows for antibodies against bovine viral diarrhea virus (BVDV) would accurately predict whether an animal persistently infected with BVDV could be detected in beef herds. SAMPLE POPULATION: 27 cow-calf herds in which the status of persistently infected calves was not known and 11 herds known to have persistently infected calves. Procedure-Detection of persistently infected calves was determined through immunohistochemical testing of tissue obtained at necropsy of all calves that died during calving season and skin (ear notch) specimens obtained from all young stock in the fall of 2002. Serum samples were collected from 30 spring-born calves and 10 mature cows. RESULTS: Optimum serologic test performance at time of weaning was detected when 10 calves were evaluated. At least 3 of 10 randomly selected calves were likely to have a titer > 1:1000 against BVDV type I or II in 53% of herds in which a persistently infected calf was detected during that year (sensitivity, 53%). However, at least 3 of 10 randomly selected calves were also likely to have a titer > 1:1000 in 20% of herds that did not have a persistently infected calf detected during that year (specificity, 80%). CONCLUSIONS AND CLINICAL RELEVANCE: Despite the use of a number of various cutoff values and sample sizes, serologic evaluation of a small number of calves or cows could not be used to accurately predict the presence of persistently infected cattle in a herd.  相似文献   

7.
A milking herd consisting of 55 Holstein cows had experienced abortions in several cows, as well as congenital malformations in 1 newborn calf. Bovine viral diarrhea virus was isolated from blood mononuclear cell samples obtained from several cattle, documenting 1 acute infection and 8 persistently infected carriers identified by clinical appearance and laboratory testing. Initial suspicion of persistently infected status in some, but not all animals, was facilitated by poor growth rates in some calves. Virus isolation was performed on transtracheal wash fluid obtained from acutely and persistently infected cattle with respiratory tract infection. We describe the measures taken to identify and characterize the infecting virus strain, and the series of actions taken to identify and eliminate persistently infected carriers in a herd experiencing several related problems that were shown to be caused by bovine viral diarrhea virus.  相似文献   

8.

Background

Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii. Prevalence data in ruminant species are important to support risk assessments regarding public and animal health. The aim was to investigate the presence of or exposure to C. burnetii in cattle, sheep, goats and moose, and to compare two enzyme-linked immunosorbent assays (ELISAs). National surveys of antibodies against C. burnetii were performed for dairy cattle (n=1537), dairy goats (n=58) and sheep (n=518). Bovine samples consisted of bulk milk, caprine of pooled milk, and ovine of pooled serum. Antibodies were investigated in moose samples (n=99) from three regions. A one-year regional cattle bulk milk survey was performed on the Isle of Gotland (n=119, four occasions). Cattle, sheep and goat samples were analysed with indirect ELISA and moose samples with complement fixation test. For the sheep, goat, and parts of the cattle survey, samples were run in parallel by ELISAs based on antigens from infected ruminants and ticks. Bulk milk samples from the regional cattle survey and vaginal swabs from a subset of the sheep herds (n=80) were analysed for the agent by polymerase chain reaction. Spatial clustering was investigated in the national cattle survey.

Results

The prevalence of antibodies in dairy herds was 8.2% with large regional differences. High risk clusters were identified in the southern regions. The prevalence among dairy herds on the Isle of Gotland varied from 55.9% to 64.6% and 46.4% to 58.9.0% for antibodies and agent, respectively, overall agreement between agent and antibodies was 85.2%. The prevalence of antibodies in sheep was 0.6%, the agent was not detected the vaginal swabs. Antibodies were not detected in goats or moose, although parts of the moose samples were collected in an area with high prevalence in cattle. The overall agreement between the two ELISAs was 90.4%.

Conclusions

The prevalence of antibodies against C. burnetii in dairy cattle in Sweden shows large regional differences. The results suggest that C. burnetii is a rare pathogen among Swedish moose, dairy goat and sheep. ELISAs based on ruminant and tick antigen performed in a similar manner under Swedish conditions.  相似文献   

9.
Identifying reservoirs and transmission routes for bovine viral diarrhea virus (BVDV) are important in developing biosecurity programs. The aim of this study was to evaluate BVDV transmission by the hematophagous horn fly (Haematobia irritans). Flies collected from four persistently infected cattle were placed in fly cages attached to principal (n?=?4) and control (n?=?4) BVDV-naïve calves housed individually in isolation rooms. Flies were able to feed on principal calves, but a barrier prevented fly feeding from control calves. Flies were tested for BVDV by RT-PCR and virus isolation at time of collection from PI cattle and after 48 h of exposure on BVDV-naïve calves. Blood samples were collected from calves and tested for BVDV infection. Virus was isolated from fly homogenates at collection from PI animals and at removal from control and principal calves. All calves remained negative for BVDV by virus isolation and serology throughout the study. Bovine viral diarrhea virus may be detected in horn flies collected from PI cattle, but horn flies do not appear to be an important vector for BVDV transmission.  相似文献   

10.

Background

Bovine paratuberculosis is an incurable chronic granulomatous enteritis caused by Mycobacterium avium subspecies paratuberculosis (MAP). The prevalence of MAP in the Swiss cattle population is hard to estimate, since only a few cases of clinical paratuberculosis are reported to the Swiss Federal Food Safety and Veterinary Office each year.Fecal samples from 1,339 cattle (855 animals from 12 dairy herds, 484 animals from 11 suckling cow herds, all herds with a history of sporadic paratuberculosis) were investigated by culture and real-time polymerase chain reaction (PCR) for shedding of MAP.

Results

By culture, MAP was detected in 62 of 445 fecal pools (13.9%), whereas PCR detected MAP in 9 of 445 pools (2.0%). All 186 samples of the 62 culture-positive pools were reanalyzed individually. By culture, MAP was grown from 59 individual samples (31.7%), whereas PCR detected MAP in 12 individual samples (6.5%), all of which came from animals showing symptoms of paratuberculosis during the study. Overall, MAP was detected in 10 out of 12 dairy herds (83.3%) and in 8 out of 11 suckling cow herds (72.7%).

Conclusions

There is a serious clinically inapparent MAP reservoir in the Swiss cattle population. PCR cannot replace culture to identify individual MAP shedders but is suitable to identify MAP-infected herds, given that the amount of MAP shed in feces is increasing in diseased animals or in animals in the phase of transition to clinical disease.  相似文献   

11.
Bovine viral diarrhea virus (BVDV) is one of the most relevant pathogens affecting today's cattle industries. Although great strides have been made in understanding this virus in cattle, little is known about the role of wildlife in the epidemiology of BVDV. While persistently infected cattle are the most important reservoir, free-ranging ungulates may become infected with BVDV as demonstrated by serosurveys and experimental infections. Therefore, free-ranging wildlife may maintain BVDV as the result of an independent cycle and may serve as a reservoir for the virus. Systematic studies on prevalence of BVDV-specific antibodies or frequency of persistent BVDV infection in North American wildlife are sparse, and no information is available from the southeastern United States. The objective of this study was to evaluate blood and skin samples from hunter-harvested white-tailed deer (Odocoileus virginianus) for evidence of BVDV infection. Virus-neutralizing antibodies were detected in 2 of 165 serum samples. Skin biopsy immunohistochemistry (IHC) was performed on samples from 406 deer using a BVDV-specific monoclonal antibody (MAb) (15c5), and BVDV antigen was detected in one sample. A similar IHC staining pattern was obtained using a second BVDV MAb (3.12F1). Viral antigen distribution in the skin sample of this deer resembled that found in persistently infected cattle and in a previously described persistently infected white-tailed deer; thus, the deer was presumed to be persistently infected. Evidence of BVDV infection in free-ranging white-tailed deer should encourage further systematic investigation of the prevalence of BVDV in wildlife.  相似文献   

12.
Several tests for Bovine viral diarrhea virus (BVDV) were applied to samples collected monthly from December 20, 2005, through November 27, 2006 (day 0 to day 342) from 12 persistently infected (PI) cattle with BVDV subtypes found in US cattle: BVDV-1a, BVDV-1b, and BVDV-2a. The samples included clotted blood for serum, nasal swabs, and fresh and formalin-fixed ear notches. The tests were as follows: titration of infectious virus in serum and nasal swabs; antigen-capture (AC) enzyme-linked immunosorbent assay (ELISA), or ACE, on serum, nasal swabs, and fresh ear notches; gel-based polymerase chain reaction (PCR) testing of serum, nasal swabs, and fresh ear notches; immunohistochemical (IHC) testing of formalin-fixed ear notches; and serologic testing for BVDV antibodies in serum. Of the 12 animals starting the study, 3 died with mucosal disease. The ACE and IHC tests on ear notches had positive results throughout the study, as did the ACE and PCR tests on serum. There was detectable virus in nasal swabs from all the cattle throughout the study except for a few samples that were toxic to cell cultures. The serum had a virus titer ≥ log10 1.60 in all samples from all the cattle except for 3 collections from 1 animal. Although there were several equivocal results, the PCR test most often had positive results. The BVDV antibodies were due to vaccination or exposure to heterologous strains and did not appear to interfere with any BVDV test. These findings illustrate that PI cattle may be identified by several tests, but differentiation of PI cattle from cattle with acute BVDV infection requires additional testing, especially of blood samples and nasal swabs positive on initial testing. Also, calves PI with BVDV are continual shedders of infectious virus, as shown by the infectivity of nasal swabs over the 11-mo study.  相似文献   

13.

Background

Bovine herpesvirus 5 (BoHV-5) is an alphaherpesvirus responsible for meningoencephalitis in young cattle and it is antigenically and genetically related to bovine herpesvirus 1. BoHV-5 outbreaks are sporadic and restricted in their geographical distribution, being mostly detected in the Southern hemisphere. The N569 and A663 strains are prototypes of the "a" and "b" subtypes of BoHV-5, however, scarce information about their in vitro and in vivo properties is currently available.

Methods

For the in vitro comparison between BoHV-5 A663 and N569 strains, viral growth kinetics, lysis and infection plaque size assays were performed. Additionally, an experimental infection of cattle with BoHV-5 A663 and N569 strains was carried out. Viral excretion, development of neurological signs, presence of specific antibodies in serum and nasal swabs and presence of latent BoHV-5 DNA in trigeminal ganglion, were analyzed. Histopathological examination of samples belonging to inoculated animals was also performed.

Results

The lytic capacity and the cell-to-cell spread was lower for the A663 strain compared to the N569 strain, however, the production of total infectious viral particles was similar between both strains. Concerning the in vivo properties, the A663 and N569 strains are able to induce similar degrees of pathogenicity in cattle.

Conclusions

Our results show that the A663 strain used in this study is less adapted to in vitro replication in MDBK cells than the N569 strain and, although slight differences were observed, both strains are able to induce a similar degree of virulence in the natural host.  相似文献   

14.
A new diagnostic approach testing tissue samples derived from cattle ear tagging for bovine viral diarrhoea virus (BVDV) antigen in a commercially available antigen capture enzyme-linked immunosorbent assay (ACE) was developed. To validate this method, 99 positive and 469 negative samples were tested. With those samples the assay yielded a sensitivity of 100% and specificity of >or=99.6%. Serum and ear tissue samples from 11 persistently infected (PI) BVDV calves were tested. While serum samples were negative after intake of colostrum, the ear tissue samples could be detected positive for BVDV all the time. Testing multiple samples derived from the same ear from PI cattle yielded positive results and low variation. Using cattle ear tags combining the ear tag application with sampling of a small ear tissue plug and testing those tissue samples with an ACE could be a reliable and economic way of BVDV testing.  相似文献   

15.
Bovine viral diarrhea virus (BVDV) has a great economic impact on the United States cattle industry. The Academy of Veterinary Consultants, the American Association of Bovine Practitioners, and the National Cattlemen's Beef Association have called for the goal of BVDV control and eventual eradication in the U.S.A. One of the key factors in such efforts will be the detection of BVDV infections, particularly targeting persistently infected animals. To assess current BVDV detection methods in the U.S.A., 26 veterinary diagnostic laboratories in 23 states were surveyed. Survey questions related to the types of tests currently offered, the number of tests performed, the reasons for test requests, the type of samples used, whether sample pooling was performed, and whether follow-up testing or information regarding bovine viral diarrhea (BVD) management was provided after positive tests. There was no clear consensus on an individual BVDV testing method, the pooling of samples or the retesting of positive animals. Ear-notch antigen capture enzyme-linked immunosorbent assay (ACE) was the test most frequently performed based on the absolute number of tests. However, when the data were adjusted to reflect individual laboratory choices, the number of ACE and immunohistochemistry tests performed on ear notches was nearly equal. Only 55% of diagnostic laboratories provided BVD management information to producers or veterinarians who submitted positive samples. There was no significant difference in the number of positive tests in laboratories that received the majority of their samples for screening purposes versus laboratories that received the majority of their samples because BVDV was suspected based on clinical signs in a herd.  相似文献   

16.
Economic losses due to infection with Bovine viral diarrhea virus (BVDV) have prompted introduction of organized control programs. These programs primarily focus on the removal of persistently infected (PI) animals, the main source of BVDV transmission. Recently, persistent BVDV infection was demonstrated experimentally in white-tailed deer, the most abundant wild ruminant in North America. Contact of cattle and white-tailed deer may result in interspecific BVDV transmission and birth of persistently infected offspring that could be a threat to control programs. The objective of this study was to assess the potential for interspecific BVDV transmission from persistently infected cattle cohabitated with pregnant white-tailed deer. Seven female and one male white-tailed deer were captured and bred in captivity. At approximately 50 days of gestation, two cattle persistently infected with BVDV 1 were cohabitated with the deer. In a pen of approximately 0.8 ha, both species shared food and water sources for a period of 60 days. Transmission of BVDV as indicated by seroconversion was demonstrated in all exposed adult deer. Of the seven pregnancies, four resulted in offspring that were infected with BVDV. Persistent infection was demonstrated in three singlet fawns by immunohistochemistry and ELISA on skin samples, PCR, and virus isolation procedures. Furthermore, two stillborn fetuses were apparently persistently infected. This is the first report of BVDV transmission from cattle to white-tailed deer using a model of natural challenge. Under appropriate circumstances, BVDV may efficiently cross the species barrier to cause transplacental infection and persistently infected offspring in a wildlife species.  相似文献   

17.

Background

Reproductive disorders associated with chlamydial infection have been reported worldwide in cattle and there are indications of potential venereal transmission.

Methods

Semen samples from 21 dairy bulls and cauda epididymidis tissue samples from 43 beef bulls were analysed for chlamydial agent by real-time polymerase chain reaction (PCR) including an internal amplification control (mimic). Additionally, presence of antibodies against Chlamydophila (Cp.) abortus among the bulls was investigated with the commercial Pourquier® ELISA Cp. abortus serum verification kit.

Results

No chlamydial agent was detected by PCR in either the semen samples or in the tissue samples. Additionally, no antibodies against Cp. abortus were detected.

Conclusions

The results suggest that Cp. abortus is very rare, or absent in Swedish bulls and thus the risk for venereal transmission of chlamydial infection through their semen is low. However, because Chlamydophila spp. infection rates seem to differ throughout the world, it is essential to clarify the relative importance of transmission of the infection through semen on cattle fertility.  相似文献   

18.
Two abortions occurred in a 150-head commercial cow-calf herd. Bovine viral diarrhea was suspected and confirmed by measuring extended titers against bovine viral diarrhea virus (BVDV) in a sample of 15 breeding females. Fifteen were sero-positive and 11 had significantly high titers (1:972-1:8748), likely due to natural exposure to cattle persistently infected with BVDV.  相似文献   

19.

Background

Bluetongue virus (BTV) is an insect-transmitted virus, which causes bluetongue disease (BT) in sheep and a fatal hemorrhagic infection in North American white-tailed deer. However, in cattle the disease is typically asymptomatic and no overt clinical signs of disease appear to be associated with BTV infection. Serological evidence and isolation of different BTV serotypes have been reported in Sudan, however, no information is currently available in regard to previous exposure of Sudanese livestock to BTV infection in East Darfur State, Sudan.

Aims

To determine the prevalence of BTV antibodies and to identify the potential risk factors associated with BTV infection among cattle in East Darfur State, Sudan.

Methods

A total of 224 blood samples were collected randomly from five localities in East Darfur State, Sudan. The serum samples were screened for detection of BTV-specific immunoglobulin G (IgG) antibodies using a competitive enzyme-linked immunosorbent assay (c-ELISA).

Results

Serological evidence of BTV infection was observed in 150 out of 224 animals accounting for a 67% prevalence rate among cattle in East Darfur State. Older cattle (>2 years of age) were six times more likely to be infected with BTV (OR = 6.62, CI = 2.87-15.26, p-value = 0.01). Regarding animal source (contact with other herds) as a risk factor, it was shown that cattle purchased from market or introduced from other herds were 3 times at higher risk of being infected with BTV (OR = 3.87, CI = 1.07-13.87, p value = 0.03). Exposure of cattle to the insect vector increased the risk of contracting BTV infection by six times compared to non-exposed cattle (OR = 6.44, CI = 1.53-27.08, p value = 0.01).

Conclusion

The present study indicated that age, animal source and the intensity of the insect vector are influential risk factors for BTV infection in cattle in the Darfur region. Surveillance for BTV infection should be extended to include other susceptible ruminants and to study the distribution of the insect vectors to better predict and respond to a possible BTV outbreak in the State of East Darfur, Sudan.  相似文献   

20.
Five diagnostic techniques performed on skin biopsies (shoulder region) and/or serum were compared for detection of bovine viral diarrhea virus infection in 224 calves 0-3 months of age, 23 calves older than 3 months but younger than 7 months, and 11 cattle older than 7 months. The diagnostic methods used were immunohistochemistry (IHC), 2 commercial antigen ELISAs, 1 commercial antibody ELISA, and real-time RT-PCR. Results of 249 out of 258 skin and serum samples were identical and correlated within the 3 antigen detection methods and the real-time RT-PCR used. Twenty-six of these 249 samples were BVDV-positive with all antigen detection methods and the real-time RT-PCR. Nine out of 258 samples yielding discordant results were additionally examined by RT-PCR, RT-PCR Reamplification (ReA), and antigen ELISA I on serum and by immunohistochemistry on formalin fixed and paraffin-embedded skin biopsies. Virus isolation and genotyping was performed as well on these discordant samples. In 3 cases, transiently infected animals were identified. Two samples positive by real-time RT-PCR were interpreted as false positive and were ascribed to cross-contamination. The antigen ELISA II failed to detect 2 BVDV-positive calves due to the presence of maternal antibodies; the cause of 2 false-positive cases in this ELISA remained undetermined. Only persistently infected animals were identified in skin samples by IHC or antigen ELISA I. The 3 antigen detection methods and the real-time RT-PCR used in parallel had a high correlation rate (96.5%) and similar sensitivity and specificity values.  相似文献   

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