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1.
Evaluation of a blocking ELISA for the detection of bovine viral diarrhoea virus (BVDV) antibodies in serum and milk 总被引：4，自引：0，他引：4
The performance characteristics of a blocking ELISA test applied to serum and individual milk for the detection of antibodies to bovine viral diarrhoea virus (BVDV) were assessed using 1189 matched milk/serum samples collected from cows of 42 dairy herds located in Brittany (west of France). This test was based on a monoclonal antibody directed against non-structural protein NS2-3 of pestiviruses. All tests were performed blind. For each type of sample, negative/positive cut-off values were determined using receiver operating characteristic (ROC) analysis. Sensitivity and specificity were estimated using the virus neutralisation test as a reference. For sera, the ROC analysis provided a negative/positive inhibition percentage cut-off value of 50% giving a sensitivity and a specificity of 96.9 and 97.8%. For individual milk samples, the cut-off was fixed at 30%, leading to a sensitivity and a specificity of 96.9 and 97.3%. Using this test, a good overall agreement was found between results obtained on matched milk/serum samples (Kappavalue=0.95). The present results indicate that this blocking ELISA test is reliable enough for use in a mass screening and control scheme on BVDV. 相似文献
2.
The Norwegian bovine virus diarrhoea (BVD) control-and-eradication program performed annual testing of the national cattle population since its first screening in January 1993. A bulk-tank milk ELISA antibody test was used for the initial screening of dairy herds. Based on the annual bulk-tank milk-test result, a binary variable denoting herd sero-conversion (a surrogate measure for incidence) was created.The count of herds with sero-conversion in each community was regressed on year and the initial herd-sero-prevalence for each community in a Poisson hierarchical trend model - modelling the risk of sero-conversion. By using this modelling approach, estimates of trend specific for each hierarchical level of organisation were included in the trend model (community, veterinary district and county) could be estimated.The main BVD trend showed a steadily declining sero-conversion risk. The communities in the highest herd-sero-prevalence quartile in 1993 continued to have the highest sero-conversion risk throughout the study period--decreasing from an average predicted sero-conversion risk in 1993 of 0.12 (95% CI; 0.10, 0.13) to 0.02 (0.007, 0.04) in 1997. There was an expressed variation in the level of sero-conversion for all the three hierarchical levels, but the trend only varied at the lowest level (community). 相似文献
3.
Rikula U Nuotio L Aaltonen T Ruoho O 《Preventive veterinary medicine》2005,72(1-2):139-42; discussion 215-9
The bovine viral diarrhoea virus (BVDV) situation among dairy herds and suckler-cow herds was monitored annually from 1998 to 2004. Bulk-tank milk (BTM) samples from all dairy herds and serum samples from beef animals at slaughter were examined for BVDV antibodies using a commercial indirect ELISA test. New BTM antibody-positive herds and herds with a history of BTM antibodies, but previously untested were sampled individually and tested for evidence of BVDV. The reason for the antibody-positivity or the source of infection was investigated. The percentage of BTM antibody-positive herds ranged from 0.45% in 2000 to 0.15% in 2003. The number of herds with persistently infected (PI) animals ranged from 10 in 2001 to 0 in 2003. The most common cause for a herd to become BTM antibody-positive was the purchase of a seropositive animal or a PI animal or a dam carrying a PI fetus. The new BVD decree of 2004 will be described in brief. 相似文献
4.
Ten years of bovine virus diarrhoea virus (BVDV) control in Norway: a cost-benefit analysis 总被引：1，自引：0，他引：1
Valle PS Skjerve E Martin SW Larssen RB Østerås O Nyberg O 《Preventive veterinary medicine》2005,72(1-2):189-207; discussion 215-9
A retrospective cost-benefit analysis was carried out on the Norwegian bovine virus diarrhoea (BVD) control and eradication strategy, for the years 1993-2003. Information regarding the control cost input parameters was gathered from the cattle industry (TINE Norwegian Dairies, GENO Breeding and AI association, and GILDE Norwegian Meat), The National Animal Health Authorities and The Veterinary Institute. We accounted for variable costs (both direct costs associated with the control, and those costs carried by the farmers as a consequence of the control program). The benefit was estimated as the difference between the assumed losses without control - represented overall as 10% increase of the observed 1993 BVD virus infection level - and the observed losses during the control period. An estimate of the financial losses associated with the BVD virus (BVDV) infection was based on studies of the herd level effects on health, reproduction, and production in dairy herds with evidence of recent BVDV infection. We used a stochastic simulation model to account for the total uncertainty in both the control cost and financial loss estimates. The annual net benefits over the 10 years of BVD control were discounted to a 1993 net present value (NPV). The median NPV of the BVD control, nationally, was estimated at 130 million NOK with a distribution of the NPV ranging from +51 to +201 million NOK (5th and 95th percentiles, respectively). Out of the total control costs the farmers and the farmer-owned industries (the co-operatives) had carried about 62% of these costs; however, the farmers were also the main beneficiaries. The Norwegian experience shows a robust cost-efficiency for a BVDV eradication strategy; this stands in sharp contrast to earlier studies where the results were not supportive. Even though every cattle population and country is unique, the Norwegian findings and experiences should have wider implications. 相似文献
5.
Our purpose was to determine direct production losses (milk loss, premature voluntary culling and reduced slaughter value, mortaliy loss, and abortion and reproductive loss) and treatmetn costs (veterinary services, medication cost, and extra farm labour cost) due to four infectious diseases in the maritime provinces of Canada: bovine viral diarrhoea (BVD), enzootic bovine leukosis (EBL), Johne's Disease (JD), and neosporosis. We used a partial-budget model, and incorporated risk and sensitivity analyses to identify the effects of uncertainty on costs. Total annual costs for an average, infected, 50 cow herd were: JD$ 2472; BVD$ 2421; neosporosis $ 2304; EBL$ 806. The stochastic nature of the proportion of infected herds and prevalence of infection within a herd were used to estimate probability distributions for these ex post costs. For all diseases, these distributions were right skewed. A sensitivity analysis showed the largest effect on costs was due to milk yield effects. For example, changing milk production loss from 0 to 5% for BVD increased the costs for the disease by 266%. 相似文献
6.
AIMS: To assess the sensitivity and specificity of a bulk tank milk (BTM) antibody enzyme-linked immunosorbent assay (ELISA) to detect likely infection of a dairy herd with bovine viral diarrhoea virus (BVDV). The ELISA was subsequently used to estimate the prevalence of likely infected herds in parts of the North Island of New Zealand. METHODS: BTM samples from 724 randomly selected dairy herds in the Waikato, Bay of Plenty and Northland regions of New Zealand were tested for BVDV antibodies. From this group, 20 herds were again randomly selected from each of the quartiles of the ELISA percentage inhibition (%INH) result. From each participant herd, serum from 15 randomly selected calves aged 6-18 months and 15 cows was collected and tested using an indirect blocking ELISA for BVDV antibodies. RESULTS: Among serum results from calves from 50 herds available for analysis, 34 (68%) herds were classified as likely non-infected (0-3 seropositive among 15 calves) and 16 (32%) as likely infected (5-15 seropositive among 15 calves). Receiver-operator characteristic (ROC) analysis identified an optimal cut-off for BTM of 80%INH associated with 81% sensitivity and 91% specificity for likely herd infection. The prevalence of BVDV antibodies in cows within herds and %INH for BVDV in bulk milk were positively correlated (p<0.01). The association between bulk milk %INH and the prevalence of BVDV antibodies in calves was stronger than the same association in cows. Based on the threshold of 80%INH, the 95% confidence interval (CI) for prevalence of likely infection in the 724 herds in the Waikato, Bay of Plenty and Northland regions of New Zealand was 12-17%. Vaccination against BVDV was not significantly associated with the likely infection status of the herd based on prevalence of BVDV antibodies among calves. CONCLUSION: An ELISA test result for BVDV antibodies in BTM >/=80%INH can be used as a threshold to indicate the presence of likely infection with BVDV in dairy herds in New Zealand, with 81% sensitivity and 91% specificity. 相似文献
7.
Antibodies against non-structural protein 3 (NS3, p80) of bovine viral diarrhoea virus (BVDV) were determined in milk from cows vaccinated with an inactivated BVDV vaccine and compared to serum antibody levels. Animals in one herd were vaccinated with an inactivated BVDV vaccine according to the standard protocol and animals from a second herd with an intensive schedule. Serum and milk samples were tested for BVDV NS3 antibodies using five commercial ELISAs. With a few exceptions, vaccination according to the standard schedule did not induce BVDV NS3-specific antibodies in serum or milk. However, after vaccination according to the intensive schedule, anti-NS3 antibodies were detected for a short time in serum and, to a lesser extent, in milk. Bulk milk was a suitable substrate for BVDV monitoring of herds vaccinated with the inactivated BVD vaccine. 相似文献
8.
In The Netherlands, a voluntary bovine virus diarrhoea virus (BVDV)-free certification programme was started in 1997. After an intake procedure in which all cattle are tested for the presence of BVD virus, a herd obtains the status "BVD-virus-free". To maintain this status a monitoring procedure is executed to verify absence of BVDV circulation in the herd. Several diagnostic tests are used: RT-PCR in bulk milk and pooled blood samples, antigen-ELISA (Ag-ELISA) and antibody ELISA in individual blood samples. Sensitivity and specificity of these tests are discussed. In addition, a diagnostic quick scan has been introduced, consisting of a combination of bulk milk tests for virus and antibody, and antibody tests in samples from young stock. Preliminary results are presented. 相似文献
9.
AIMS: To assess the sensitivity and specificity of a bulk tank milk (BTM) antibody enzyme-linked immunosorbent assay (ELISA) to detect likely infection of a dairy herd with bovine vi- ral diarrhoea virus (BVDV). The ELISA was subsequently used to estimate the prevalence of likely infected herds in parts of the North Island of New Zealand. METHODS: BTM samples from 724 randomly selected dairy herds in the Waikato, Bay of Plenty and Northland regions of New Zealand were tested for BVDV antibodies. From this group, 20 herds were again randomly selected from each of the quartiles of the ELISA percentage inhibition (%INH) result. From each participant herd, serum from 15 randomly selected calves aged 6–18 months and 15 cows was collected and tested using an indirect blocking ELISA for BVDV antibodies. RESULTS: Among serum results from calves from 50 herds available for analysis, 34 (68%) herds were classified as likely non-infected (0-3 seropositive among 15 calves) and 16 (32%) as likely infected (5–15 seropositive among 15 calves). Receiver- operator characteristic (ROC) analysis identified an optimal cut-off for BTM of 80%INH associated with 81% sensitivity and 91% specificity for likely herd infection. The prevalence of BVDV antibodies in cows within herds and %INH for BVDV in bulk milk were positively correlated (p<0.01). The association between bulk milk %INH and the prevalence of BVDV antibodies in calves was stronger than the same association in cows. Based on the threshold of 80%INH, the 95% confidence interval (CI) for prevalence of likely infection in the 724 herds in the Waikato, Bay of Plenty and Northland regions of New Zealand was 12–17%. Vaccination against BVDV was not significantly associated with the likely infection status of the herd based on prevalence of BVDV antibodies among calves. CONCLUSION: An ELISA test result for BVDV antibodies in BTM ≥80%INH can be used as a threshold to indicate the presence of likely infection with BVDV in dairy herds in New Zealand, with 81% sensitivity and 91% specificity. 相似文献
10.
Following several clinical cases of suspected bovine virus diarrhoea (BVD) on three Namibian cattle farms, a serological survey was conducted on bovine, ovine, caprine and wild ruminant sera originating from different regions of the country. Neutralizing antibodies to BVD virus (BVDV) were detected in 58% of 1,014 cattle sera, 14% of 618 sheep sera and 4.6% of 1,118 goat sera. Sera from seven of ten wildlife species were positive with kudu, eland and giraffe having prevalence rates greater than 40%. BVDV was isolated from six clinically affected bovines and three healthy heifers persistently infected with BVDV. The survey demonstrated that pestivirus infections are widespread in Namibia in both domestic and wild ruminants. 相似文献
11.
The validation of assays for bovine immunodeficiency virus (BIV) in cattle is hampered by the absence of a gold standard. Two tests that often are used to detect BIV are the indirect fluorescent-antibody assay (IFA) and the nested-set polymerase chain-reaction assay (PCR). IFA detects an antibody response whereas PCR detects the provirus in white blood cells.Using Bayesian techniques performed simultaneously on animals from two different dairy herds, we estimated the performance of the IFA and PCR assays and infection prevalence. Bayesian techniques also were used to derive posterior distributions of sensitivities, specificities, and prevalences. The Bayesian estimates were IFA sensitivity=60%, IFA specificity=88%, PCR sensitivity=80%, PCR specificity=86%, Herd A prevalence=20%, and Herd B prevalence=71%. Although PCR was the more sensitive assay, substantial misclassification of infection would be expected in epidemiological studies of BIV regardless of which assay was used. 相似文献
12.
A W McClurkin S R Bolin M F Coria 《Journal of the American Veterinary Medical Association》1985,186(6):568-569
Both cytopathic and noncytopathic bovine viral diarrhea virus (BVDV) were isolated from 16 of 17 bovine spleens representing 11 herds that had experienced acute BVD and from 12 of 21 bovine spleens from 1 herd affected with chronic BVD. It was concluded that isolation of cytopathic and noncytopathic BVDV from the same spleen probably indicates that an animal with a persistent, noncytopathic BVDV infection was superinfected with a cytopathic BVDV. The prevalence (greater than 70%) of 2 viruses in the spleen of cattle with acute or chronic BVD suggested that persistent infection with noncytopathic BVDV may be an important factor in the pathogenesis of BVD. 相似文献
13.
Our objective in this cross-sectional study was to determine the seroprevalence in 1996 of commercial dairy herds in central Chile positive to bovine viral diarrhea (BVD) virus, by the detection of antibodies in bulk-tank milk samples. Samples were obtained from 501 dairy farms ( approximately 50,000 cows) from the Metropolitan, VI, VII and VIII regions of Chile. An indirect ELISA was used to detect BVD antibodies. An absorbance (A450) > or = 0.55 was considered positive. The apparent proportion of positive herds ranged from 71.2 to 83% by region and did not differ by region. We concluded that exposure to BVD was widely distributed in the central area of Chile in 1996. 相似文献
14.
15.
Sandvik T 《Veterinary microbiology》1999,64(2-3):123-134
There are no pathognomonic clinical signs of infection with bovine viral diarrhoea virus (BVDV) in cattle. Diagnostic investigations therefore rely on laboratory-based detection of the virus, or of virus-induced antigens or antibodies in submitted samples. In unvaccinated dairy herds, serological testing of bulk milk is a convenient method for BVDV prevalence screening. Alternatively, serological testing of young stock may indicate if BVDV is present in a herd. In BVDV positive herds, animals persistently infected (PI) with BVDV can be identified by combined use of serological and virological tests for examination of blood samples. ELISAs have been used for rapid detection of both BVDV antibodies and antigens in blood, but should preferably be backed up by other methods such as virus neutralization, virus isolation in cell cultures or amplification of viral nucleic acid. Detailed knowledge of the performance of the diagnostic tests in use, as well as of the epidemiology of bovine virus diarrhoea is essential for identification of viremic animals in affected herds. 相似文献
16.
Studies covering all aspects of bovine viral diarrhoea virus (BVDV) have been conducted in several countries in Europe, Asia and America. In southern Africa, more information is required about the nature of BVDV infection, the prevalence of different strains and the economic importance of the disease. The presence of BVDV in southern Africa has been known since the early 1970s through serological surveys but few reports confirming its presence by virus isolation and correlation with clinical disease are available. Specimens (n = 312) collected in 1998/99, from live and dead cattle from different farming systems, were obtained from private practitioners, feedlot consultants and abattoirs throughout the country. Specimens (n = 37) from African buffaloes (Syncerus caffer) in the Kruger National Park were also included. All specimens were processed for virus isolation in cell culture with confirmation by means of immunofluorescent antibody tests and some also by means of an antigen capture ELISA. BVDV was isolated from 15 (4.7%) cattle and were all noncytopathic biotypes. BVDV was not detected in 37 lymph nodes obtained from buffaloes in the Kruger National Park. Of the clinical signs in cattle from which virus were isolated, respiratory signs was the most frequent (10/15), followed by diarrhoea (5/15). Abortion, congenital malformations, haemorrhagic diarrhoea and poor growth were also included as criteria for selection of animals for specimen collection, but no BVD viruses were isolated from cattle manifesting these clinical signs. 相似文献
17.
The biological properties of bovine viral diarrhoea virus (BVDV) strain Oregon C24V were studied after intranasal and subcutaneous infection of pregnant sows. This virus strain is widely used in Hungary for immunising cattle against bovine viral diarrhoea (BVD). Based upon the results of the clinical, gross pathological, histopathological and virological examinations it can be established that the given strain caused asymptomatic infection and serological conversion in sows that were in the second third of gestation. The virus caused clinically apparent disease in some of the piglets born at term, which indicates that it had crossed the placenta. More than half (57%) of the live-born piglets died within 60 days of birth. The sows and their progeny did not shed the virus. BVDV infection has great differential diagnostic importance in pigs, as classical swine fever (CSF) virus strains of reduced virulence cause similar clinical symptoms and gross and histopathological changes. 相似文献
18.
Influence of new infection with bovine virus diarrhoea virus on udder health in Norwegian dairy cows
Waage S 《Preventive veterinary medicine》2000,43(2):123-135
A retrospective longitudinal study was conducted to examine whether the exposure of dairy herds to bovine virus diarrhoea virus (BVDV) affected udder health. All Norwegian dairy herds that had experienced a marked increase in the BVDV antibody titres in bulk milk (from a level corresponding to an optical density (OD) <0.25 to >0.55, as determined by an indirect enzyme-linked immunosorbent assay) between two nation-wide herd screening examinations carried out late in 1992 and 1993, respectively, were considered to have been exposed to BVDV during the period between the examinations. The reference group included all dairy herds in which the bulk milk was BVDV antibody-negative or had only very low titres of BVDV antibodies (OD <0.25) each year from 1992 to 1995. The annual incidence rate of clinical mastitis, the bulk-milk somatic-cell count, and the annual rate of culling because of mastitis in the herds, were compared in the year of BVDV exposure (1993) as well as in a period prior to exposure (from 1988 to 1992) and two years following the year of exposure. In herds exposed to BVDV, there was a 7% increase in the incidence rate of clinical mastitis in the year of exposure, as compared with the nonexposed herds. No significant changes attributable to BVDV exposure were observed in the bulk-milk somatic-cell count or in the rate of culling because of mastitis. 相似文献
19.
A state-transition model was developed to examine the control of bovine virus diarrhoea (BVD) virus (BVDV) infections epidemiologically and economically at the farm level, using a computer spreadsheet program. The model offers the possibility of comparing and evaluating the alternatives ‘no intervention’ and ‘culling carriers’. All input variables can easily be modified to suit different conditions and areas, making it a flexible tool for policy making and decision support. Results of calculations with the most likely input values for Dutch conditions showed that culling the carriers which were persistently infected after an outbreak of BVD was economically unattractive (especially if there was any risk of reinfection). Further research is desired (1) to model the losses due to immunosuppression caused by BVDV infection, and (2) to predict more precisely the spread of BVDV after culling the carriers. 相似文献
20.
F. Beaudeau C. Belloc H. Seegers S. Assi P. Pourquier A. Joly 《Zoonoses and public health》2001,48(9):705-712
Bulk and individual milk samples from 117 herds located in Brittany (west France) were used to assess: (i) the performance characteristics of an indirect enzyme‐linked immunosorbent assay (ELISA) applied to individual milk for the detection of antibodies to bovine viral diarrhoea virus (BVDV); and (ii) the relationship between the bulk milk result obtained from this test and the within‐herd prevalence of antibody‐positive lactating cows. This ELISA test was based on a monoclonal antibody directed against non‐structural protein NS2‐3 of pestiviruses. At the individual level, based on 1113 matched milk/serum samples, the sensitivity and specificity of this test applied to milk, compared with the virus neutralization test on serum, were 95.0 and 97.7%, respectively. At the herd level, the relationship between the optical density percentage (OD%) of bulk milk and the within‐herd prevalence of antibody‐positive lactating cows was assessed using the receiver operating characteristics (ROC) analysis. Classes of OD% of bulk milk were determined so that they were associated with minimum intraclass and maximum between‐class variances of within‐herd prevalence of antibody‐positive cows. The ROC analysis resulted in two classes of bulk milk results corresponding to different expected levels of within‐herd prevalence. Herds with an OD% of bulk milk <75% and ≥75% had a mean observed prevalence of antibody‐positive cows of 8.9 and 60.6%, respectively. Herds with a bulk milk result <75% were expected to be BVDV free, whereas large variations in prevalence of antibody‐positive cows existed in the herds with OD% ≥75%. The test described in this study is suitable to identify herds likely to have a low prevalence of BVDV antibody‐positive cows. 相似文献