scholarly journals Bayesian Estimation of the True Seroprevalence and Risk Factor Analysis of Bovine Leukemia Virus Infection in Pakistan

Animals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1404
Author(s):  
Ali Sakhawat ◽  
Marzena Rola-Łuszczak ◽  
Zbigniew Osiński ◽  
Nazia Bibi ◽  
Jacek Kuźmak
Keyword(s):  
Risk Factor ◽  
Dairy Cattle ◽  
Bovine Leukemia Virus ◽  
Water Buffalo ◽  
Leukemia Virus ◽  
Credible Interval ◽  
Indigenous Cattle ◽  
Herd Level ◽  
Exotic Breed ◽  
Posterior Estimate

The objective of this study was to determine the true seroprevalence of bovine leukemia virus (BLV) infection in dairy cattle from Pakistan at the animal and herd-level. We tested 1380 dairy cattle from 451 herds and 92 water buffalo. The sera were tested by ELISA and the results were analyzed using Bayesian inference. The median posterior estimate of the herd level true BLV prevalence was 1.4%, with a 95% credible interval (CI) 0.7–3.1, whereas the median posterior estimate of the within-farm true seroprevalence was 3.8% with a 95% CI 2.8–4.8. All 92 sera collected from water buffalo were negative. Several risk factors potentially associated with seropositivity to BLV infections in Pakistan were analyzed using logistic regression model based on calculation of an odds ratio (OR). The study showed an association between seropositivity and medium herd (≥50) size (OR = 23.57, 95% CI: 3.01–103.48). Common housing of indigenous cattle with exotic-breed cattle (OR = 0.67, 95% CI: 06–2.35) or housing indigenous or their crossbred cattle with exotic-breed cattle (OR = 0.95, 95% CI: 0.14–3.01) had no effect on the BLV seroprevalence. Similarly, common housing of cattle and water buffalo was not risk factor for increased BLV seropositivity (OR = 27.10, 95% CI: 0.63–119.34).

scholarly journals Prevalence of Bovine Leukemia Virus Antibodies in US Dairy Cattle

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Rebecca M. LaDronka ◽  
Samantha Ainsworth ◽  
Melinda J. Wilkins ◽  
Bo Norby ◽  
Todd M. Byrem ◽  
...  
Keyword(s):  
Dairy Cattle ◽  
Dairy Cows ◽  
Bovine Leukemia Virus ◽  
Leukemia Virus ◽  
Herd Size ◽  
Cross Sectional ◽  
Herd Level ◽  
Apparent Prevalence ◽  
Observational Study Design ◽  
Epidemiologic Features

Objective. To estimate current US herd-level and animal-level prevalence of bovine leukemia virus (BLV) in dairy cows and characterize epidemiologic features. Design. Cross-sectional observational study design and survey. Animals. 4120 dairy cows from 103 commercial dairy herds in 11 states across the US. Procedures. Milk samples were collected from dairy cows through routine commercial sampling and tested for anti-BLV antibodies by antibody capture ELISA. Based on the ELISA results of a sample of an average of 40 cows per herd, within-herd apparent prevalence (AP) was estimated by a directly standardized method and by a lactation-weighted method for each herd. Within-herd AP estimates were summarized to give estimates of US herd-level and animal-level AP. Differences in AP by lactation, region, state, breed, and herd size were examined to characterize basic epidemiologic features of BLV infection. Results. 94.2% of herds had at least one BLV antibody positive cow detected. The average within-herd standardized AP was 46.5%. Lactation-specific AP increased with increasing lactation number, from 29.7% in first lactation cows to 58.9% in 4th and greater lactation cows. Significant differences were not observed based on region, state, breed, or herd size. Conclusions and Clinical Relevance. These results are consistent with a historical trend of increasing prevalence of BLV among US dairy cattle. Given the findings of other studies on the negative impacts of BLV infection on milk production and cow longevity, these findings are clinically relevant for veterinarians counseling dairy clients on the risks of BLV to their herds.

Lack of association between amino acid sequences of the bovine leukemia virus envelope and varying stages of infection in dairy cattle

2020 ◽  
Vol 278 ◽  
pp. 197866
Author(s):  
Fernando Cerón Téllez ◽  
Ana Silvia González Méndez ◽  
Jorge Luis Tórtora Pérez ◽  
Elizabeth Loza-Rubio ◽  
Hugo Ramírez Álvarez
Keyword(s):  
Amino Acid ◽  
Dairy Cattle ◽  
Bovine Leukemia Virus ◽  
Leukemia Virus ◽  
Amino Acid Sequences ◽  
Virus Envelope

Epidemiologic Study on Enzootic Bovine Leukemia Using Serologic Tests and Hematologic Examinations

1977 ◽  
Vol 63 (5) ◽  
pp. 407-413
Author(s):  
Domenico Rutili ◽  
Maurizio Severini ◽  
Luigi Rampichini ◽  
Francesco Titoli ◽  
Umberto Chicchini
Keyword(s):  
Dairy Cattle ◽  
Bovine Leukemia Virus ◽  
Leukemia Virus ◽  
Epidemiologic Study ◽  
Diagnostic Procedures ◽  
Blood Picture ◽  
Electron Microscopic ◽  
Serologic Tests ◽  
Epidemiologic Survey ◽  
History Of

In order to find suitable diagnostic procedures to use in an epidemiologic survey for the detection of animals infected with the bovine leukemia virus (BLV), the authors conducted an investigation on 262 Friesian dairy cattle. The results of hematologic, serologic, and electron microscopic examinations are reported. Evaluation of the results demonstrated the validity of the immunodiffusion and immunofluorescence tests and the opportunity for their use in conjunction with examination of the blood picture. From the data reported it would appear useful to extend the investigation to the herds without history of lymphosarcoma.

scholarly journals A hematologic key for bovine leukemia virus screening in Japanese black cattle

2019 ◽  
Vol 31 (4) ◽  
pp. 568-571
Author(s):  
Masataka Akagami ◽  
Shoko Oya ◽  
Yuki Kashima ◽  
Satoko Seki ◽  
Yoshinao Ouchi ◽  
...  
Keyword(s):  
Dairy Cattle ◽  
Bovine Leukemia Virus ◽  
Operating Characteristic ◽  
Leukemia Virus ◽  
Characteristic Curve ◽  
Persistent Lymphocytosis ◽  
Cutoff Values ◽  
Antibody Elisa ◽  
Hematologic Method ◽  
Virus Screening

The European Community’s leukosis key (EC key) is a well-known hematologic method for detecting bovine leukemia virus (BLV) infection in dairy cattle. The key identifies infected cattle with persistent lymphocytosis via a combination of lymphocyte count (LC) and age. Using the EC key to identify BLV-infected Japanese black (JB) cattle is problematic, however, given the inherently lower LCs of JB cattle compared to dairy cattle. We analyzed the LC in BLV-positive and -negative JB cattle and estimated LC cutoff values by age using receiver operating characteristic curve analysis. Among the 716 JB blood samples collected, 452 (63%) JB cattle were confirmed as BLV-positive by an antibody ELISA for ≥1-y-old cattle and by real-time PCR for <1-y-old cattle. The cutoff values for the LC in each age group were calculated as 6.3 × 109/L for <1 y, 5.9 × 109/L for 1 to <2 y, 5.5 × 109/L for 2 to <3 y, 4.5 × 109/L for 3 to <6 y, 4.3 × 109/L for 6 to ≤10 y, and 3.7 × 109/L for >10 y. The sensitivity and specificity of the estimated cutoff values were 0.49 (95% confidence interval: 0.44–0.53) and 0.81 (0.75–0.85), whereas those of the EC key were 0.20 (0.16–0.24) and 0.99 (0.97–1.00). Our LC cutoff values for screening JB cattle for BLV infection appear to be preferable to those of the EC key.

Vertical transmission of bovine leukemia virus and bovine immunodeficiency virus in dairy cattle herds

2002 ◽  
Vol 84 (3) ◽  
pp. 275-282 ◽  
Author(s):  
Sothy Meas ◽  
Tatsufumi Usui ◽  
Kazuhiko Ohashi ◽  
Chihiro Sugimoto ◽  
Misao Onuma
Keyword(s):  
Dairy Cattle ◽  
Vertical Transmission ◽  
Bovine Leukemia Virus ◽  
Leukemia Virus ◽  
Bovine Immunodeficiency Virus ◽  
Immunodeficiency Virus ◽  
Cattle Herds

scholarly journals Evaluation of a New Antibody-Based Enzyme-Linked Immunosorbent Assay for the Detection of Bovine Leukemia Virus Infection in Dairy Cattle

2005 ◽  
Vol 17 (5) ◽  
pp. 451-457 ◽  
Author(s):  
Gustavo E. Monti ◽  
Klaas Frankena ◽  
Bas Engel ◽  
Willem Buist ◽  
Héctor D. Tarabla ◽  
...  
Keyword(s):  
Maximum Likelihood ◽  
Dairy Cattle ◽  
Immunosorbent Assay ◽  
Bovine Leukemia Virus ◽  
Conditional Independence ◽  
Latent Class ◽  
Leukemia Virus ◽  
Latent Class Model ◽  
Enzyme Linked Immunosorbent Assay ◽  
Conditional Dependence

The objective of this study was to validate a new blocking enzyme-linked immunosorbent assay (ELISA) (designated M108 for milk and S108 for serum samples) for detecting bovine leukemia virus (BLV) infection in dairy cattle. Milk, serum, and ethylenediaminetetraacetic acid–blood samples were collected from 524 adult Holstein cows originating from 6 dairy herds in Central Argentina. The M108 and S108 were compared with agar gel immunodiffusion (AGID), polymerase chain reaction and a commercial ELISA. Because there is currently no reference test capable of serving as a gold standard, the test sensitivity (SE) and specificity (SP) were evaluated by the use of a latent class model. Statistical inference was performed by classical maximum likelihood and by Bayesian techniques. The maximum-likelihood analysis was performed assuming conditional independence of tests, whereas the Bayesian approach allowed for conditional dependence. No clear conclusion could be drawn about conditional dependence of tests. Results with maximum likelihood (under conditional independence) and posterior Bayes (under conditional dependence) were practically the same. Conservative estimates of SE and SP (with 95% confidence intervals) for M108 were 98.6 (96.7; 99.6) and 96.7 (92.9; 98.8) and for S108 99.5 (98.2; 99.9) and 95.4 (90.9; 98.1), respectively. The ELISA 108 using either milk or serum to detect BLV-infected animals had comparable SE and SP with the official AGID and a commercial ELISA test, which are currently the most widely accepted tests for the serological diagnosis of BLV infection. Therefore, ELISA 108 can be used as an alternative test in monitoring and control programs.

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