Prevalence Of Bovine Viral Diarrhea Virus Research Articles

Establishment of a duplex TaqMan-based real time RT-PCR assay for simultaneous detection of BRSV and BVDV.

Bovine respiratory disease complex (BRDC) represents a global acute respiratory condition that imposes substantial economic burdens on the cattle industry due to its high morbidity and mortality rates. Various factors contribute to the development of BRDC, including pathogen infections, environmental stresses, weaning of calves, and herd relocation. Viral pathogens, notably bovine respiratory syncytial virus (BRSV) and bovine viral diarrhea virus (BVDV), play a critical role in the etiology of BRDC, with single or combined viral infections being particularly clinically significant. In this study, we developed a duplex TaqMan-based real-time RT-PCR assay targeting the conserved regions of the F gene of BRSV and the 5' UTR sequence of BVDV. The limits of detection for BRSV and BVDV were 6.83 copies/μL and 5.24 copies/μL, respectively. Our validation data suggest the assay has excellent sensitivity, specificity and reproducibility. Testing of clinical samples revealed prevalence of BRSV and BVDV in local farms in Jiangsu Province, China. This study provides an efficient diagnostic tool for the epidemiological investigation of BRDC.

Comparative Analysis of the Prevalence of Bovine Viral Diarrhea Virus in Cattle Populations Based on Detection Methods: A Systematic Review and Meta-Analysis.

Infectious diseases of cattle, including bovine viral diarrhea (BVD), pose a significant health threat to the global livestock industry. This study aimed to investigate the prevalence and risk factors associated with bovine viral diarrhea virus (BVDV) infections in cattle populations through a systematic review and meta-analysis. PubMed, Web of Science, and Scopus were systematically searched for relevant articles reporting the prevalence of and associated risk factors in studies published between 1 January 2000 and 3 February 2023. From a total of 5111 studies screened, 318 studies were included in the final analysis. BVDV prevalence in cattle populations was estimated using various detection methods. The analysis detected heterogeneity in prevalence, attributed to detection techniques and associated risk factors. Antibody detection methods exhibited a higher prevalence of 0.43, reflecting the cumulative effect of detecting both active and past infections. Antigen detection methods showed a prevalence of 0.05, which was lower than antibody methods. A prevalence of 0.08 was observed using nucleic acid detection methods. The health status of the examined cattle significantly influenced the prevalence of BVDV. Cattle with bovine respiratory disease complex (BRDC) exhibited higher antibody (prevalence of 0.67) and antigen (prevalence 0.23) levels compared to cattle with reproductive problems (prevalence 0.13) or diarrhea (prevalence 0.01). Nucleic acid detection methods demonstrated consistent rates across different health conditions. Age of cattle influenced prevalence, with higher rates in adults compared to calves. Risk factors related to breeding and reproduction, such as natural or extensive breeding and a history of abortion, were associated with increased prevalence. Coinfections with pathogens like bovine herpesvirus-1 or Neospora caninum were linked to higher BVDV prevalence. Management practices, such as commingling, introducing new cattle, and direct contact with neighboring farms, also influenced prevalence. Herd attributes, including larger herd size, and the presence of persistently infected cattle, were associated with higher prevalence. These findings indicated the importance of detection methods and risk factors in BVDV epidemiological studies.

Caracterización genética del virus de la diarrea viral bovina detectado en granjas de traspatio en México

Infection by bovine viral diarrhea virus (BVDV) in cattle remains a source of significant economic losses for livestock producers. This virus is classified within the Pestivirus genus, including three main species: Pestivirus A (BVDV-1), Pestivirus B (BVDV-2), and Pestivirus H (HoBi-like pestivirus). Here, we performed a molecular epidemiological investigation aiming to evaluate the genetic diversity of BVDV in cattle from backyard farms in a municipality in Mexico named Tepalcingo, Morelos, with records of reproductive disorders. RT-PCR was conducted in 111 serum samples from affected cattle. Viral RNA was detected in 47.74% of the samples analyzed. Sequencing and phylogenetic analysis based on 5'UTR showed that the circulating subgenotype was BVDV-1a in all positive samples. These findings reveal the prevalence of BVDV in the surveyed population; thus suggesting a possible association with the previous records of reproductive manifestation in the herd. However, further studies are needed to confirm BVDV as the causative agent. Additionally, our results represent a helpful tool for designing control and prevention strategies accurate to the current regional epidemiological situation. Moreover, obtained information from this type of epidemiological study will assist the implementation of biosafety measures on backyard farms with limited economic resources.

Forsythiaside A Improves the Inhibitory Efficiency of Recombinant Protein Vaccines against Bovine Viral Diarrhea Virus Infection.

Bovine viral diarrhea virus (BVDV) is a critical animal pathogen that leads to cattle production losses associated with acute disease, immune dysregulation, reproductive failure, and respiratory disease. Due to the monotonous control technique and neglect of BVDV, increasing prevalence of BVDV has caused significant economic losses in the cattle industry worldwide. Therefore, novel anti-BVDV drugs are essential to prevent and control BVDV. Our previous studies have found that Forsythoside A (FTA) could inhibit the replication of BVDV via TRAF2-dependent CD28-4-1BB signaling in bovine peripheral blood mononuclear cells (PBMCs), but whether they can directly inhibit the BVDV remains unclear. Here, we further investigated the effects of FTA on BVDV and its underlying mechanisms of action. We found that FTA significantly inhibited the replication of BVDV in the MDBK cell directly. The results demonstrated that FTA could reduce the functional activation of Caspase-1 to inhibit the inflammatory response caused by BVDV infection and increase the expression of type I interferon (IFN-I) to clear the virus in vitro. The animal experiment was performed to evaluate the antiviral effect of FTA in vivo. Notably, after challenged with BVDV, mice with FTA + Erns-E2 protein displayed alleviated pathological damage and decreased the viral load in the spleen compared with mice inoculated with Erns-E2 protein. Furthermore, treatment with FTA enhanced body defense and delayed infection by the BVDV. Our results reveal that FTA suppresses BVDV replication both in vitro and in vivo and therefore shows promise as an anti-BVDV agent.

Seroprevalence of bovine viral diarrhea virus antibodies and risk factors in dairy cattle from the central desert of Iran

Bovine viral diarrhea virus (BVDV) infects cattle worldwide and causes one of the most important economic diseases of the dairy industry. BVDV infection reduces reproductive efficiency, suppresses the immune system, and causes gastrointestinal and respiratory diseases. A first cross-sectional study was conducted in the central desert of Iran (Yazd and South Khorasan provinces) to estimate the seroprevalence and identify BVDV-related risk factors in dairy cattle. A total of 800 cows were randomly selected of 76 herds, and their serum samples were tested by the indirect enzyme-linked immunosorbent assay (ELISA) method for BVDV antibody detection. Data were analyzed using the logistic regression model. The serum prevalence of BVDV at animal and herd levels was 66.83% and 91.6%, respectively. Traditional housing system (OR = 3.22; 95% CI = 1.20-9.09) and cattle introduction to the herd (OR = 2.12; 95% CI = 1.21-3.70) were the important risk factors for BVDV seropositivity (p < 0.05). Increasing of age per year caused adding in 0.33 log (odds) of BVDV seropositivity (p < 0.05). It is necessary to implement control and eradication programs because of the high seroprevalence at the individual level and at the herd in the central desert of Iran.

Output-based assessment of herd-level freedom from infection in endemic situations: Application of a Bayesian Hidden Markov model

Countries have implemented control programmes (CPs) for cattle diseases such as bovine viral diarrhoea virus (BVDV) that are tailored to each country-specific situation. Practical methods are needed to assess the output of these CPs in terms of the confidence of freedom from infection that is achieved. As part of the STOC free project, a Bayesian Hidden Markov model was developed, called STOC free model, to estimate the probability of infection at herd-level. In the current study, the STOC free model was applied to BVDV field data in four study regions, from CPs based on ear notch samples. The aim of this study was to estimate the probability of herd-level freedom from BVDV in regions that are not (yet) free. We additionally evaluated the sensitivity of the parameter estimates and predicted probabilities of freedom to the prior distributions for the different model parameters. First, default priors were used in the model to enable comparison of model outputs between study regions. Thereafter, country-specific priors based on expert opinion or historical data were used in the model, to study the influence of the priors on the results and to obtain country-specific estimates.The STOC free model calculates a posterior value for the model parameters (e.g. herd-level test sensitivity and specificity, probability of introduction of infection) and a predicted probability of infection. The probability of freedom from infection was computed as one minus the probability of infection. For dairy herds that were considered free from infection within their own CP, the predicted probabilities of freedom were very high for all study regions ranging from 0.98 to 1.00, regardless of the use of default or country-specific priors. The priors did have more influence on two of the model parameters, herd-level sensitivity and the probability of remaining infected, due to the low prevalence and incidence of BVDV in the study regions. The advantage of STOC free model compared to scenario tree modelling, the reference method, is that actual data from the CP can be used and estimates are easily updated when new data becomes available.

Prevalence of Bovine Viral Diarrhea Virus in Ovine and Caprine Flocks: A Global Systematic Review and Meta-Analysis.

Background: Bovine viral diarrhea virus (BVDV) is the causative agent of bovine viral diarrhea. It can infect cattle, sheep, pigs, and other animals, causing diarrhea, miscarriage, and stillbirth, among other symptoms, and it can result in huge economic losses to animal husbandry. There are reports on BVDV infection rates in sheep and goat herds from all over the world and this meta-analysis aimed to evaluate the prevalence of and risk factors for BVDV in sheep and goats.Results: Using the data of 41,297 sheep and goats in 24 countries/regions to calculate a comprehensive prevalence rate for BVDV. The overall prevalence of BVDV infection in sheep and goats was estimated to be 8.6% (95% CI: 5.2–12.7) by immunological methods and 7.3% (95% CI: 2.7–13.7) by molecular methods. Analysis by national income level revealed that prevalence is higher in middle-income countries than in high-income countries (P < 0.05). The study also compared prevalence rates by species of BVDV, sampling year, and test species, but did not find significant differences.Conclusion: This systematic review and meta-analysis is the first to determine the global prevalence of BVDV in ovine and caprine flocks. The prevalence of BVDV in sheep and goat populations varies from region to region, and the situation is not optimistic in some countries.

Novel potent IFN-γ-inducing CD8+ T cell epitopes conserved among diverse Bovine Viral Diarrhea Virus strains

Abstract Studies of immune responses elicited by Bovine Viral Diarrhea Virus (BVDV) vaccines have primarily focused on the characterization of neutralizing B cell and CD4+ T cell epitopes. Despite availability of vaccines for decades, BVDV prevalence in cattle remains largely unaffected. There is limited knowledge regarding the role of BVDV-specific CD8+ T cells in immune protection and indirect evidence suggests that they play a crucial role during BVDV infection. In this study, presence of BVDV-specific CD8+ T cells that are highly cross-reactive in cattle was demonstrated. Most importantly, novel potent IFN-γ-inducing CD8+ T cell epitopes were identified from different regions of BVDV polyprotein. Eight CD8+ T cell epitopes were identified from structural BVDV antigens: Erns, E1, and E2 glycoproteins. In addition, from nonstructural BVDV antigens: Npro, NS2-3, NS4A-B, and NS5A-B, twenty CD8+ T cell epitopes were identified. Majority of these IFN-γ-inducing CD8+ T cell epitopes were found to be highly conserved among more than two hundred strains from BVDV-1 and -2 genotypes. These conserved epitopes were also validated as cross-reactive since they induced high recall IFN-γ+ CD8+ T cell responses, ex vivo, in purified CD8+ T cells from BVDV-1- and -2-immunized cattle. Altogether, twenty-eight bovine MHC I-binding epitopes were identified from key BVDV antigens that can elicit broadly reactive CD8+ T cells against diverse BVDV strains. The data presented here will lay the groundwork for the development of a contemporary CD8+ T cell-based BVDV vaccine capable of addressing BVDV heterogeneity more effectively than current vaccines.

Prevalence of bovine viral diarrhea virus antibodies and risk factors in dairy cattle in Gondar city, Northwest Ethiopia

Bovine viral diarrhea (BVD) is a disease that affects cattle and other ruminants worldwide and causes considerable economic losses. A cross-sectional study was carried out between December 2017 and July 2018 with the aim to estimate the prevalence of Bovine Viral Diarrhea virus (BVDV) antibodies and to identify potential risk factors associated with the occurrence of the disease in dairy cattle in peri-urban areas of Gondar city, Northwest Ethiopia. A total of 339 serum samples obtained from randomly selected dairy cattle aged 6 months and older were assayed using a BVDV antibody competitive-Enzyme Linked Immunosorbent Assay (c-ELISA) kit. Descriptive statistics were used to estimate antibody prevalence of BVDV at animal and herd-level and logistic regression was used to identify potential risk factors. The study findings showed that the animal-level antibody prevalence of BVDV in the study area was 26.84 % (95 % CI: 22.1 %–31.6 %) and the herd-level seroprevalence was 68.3 % (95 % CI: 56.2 %–80.4 %). Logistic regression model demonstrated that age >2 years (OR = 4.75, 95 % CI: 2.20−10.26), herd size >11 (OR = 7.28, 95 % CI: 2.50−21.22), and poor farm hygiene (OR = 3.69, 95 % CI: 1.94−7.02), are potential risk factors associated with BVDV infection (P < 0.05). However, sex, faecal consistency and housing system were not associated with BVDV serostatus. The animal- and herd-level seroprevalence reports in Northwest Ethiopia can serve as a baseline finding for future BVD epidemiological investigations and to inform future control programs in the study region.

Novel Potent IFN-γ-Inducing CD8+ T Cell Epitopes Conserved among Diverse Bovine Viral Diarrhea Virus Strains.

Studies of immune responses elicited by bovine viral diarrhea virus (BVDV) vaccines have primarily focused on the characterization of neutralizing B cell and CD4+ T cell epitopes. Despite the availability of commercial vaccines for decades, BVDV prevalence in cattle has remained largely unaffected. There is limited knowledge regarding the role of BVDV-specific CD8+ T cells in immune protection, and indirect evidence suggests that they play a crucial role during BVDV infection. In this study, the presence of BVDV-specific CD8+ T cells that are highly cross-reactive in cattle was demonstrated. Most importantly, novel potent IFN-γ-inducing CD8+ T cell epitopes were identified from different regions of BVDV polyprotein. Eight CD8+ T cell epitopes were identified from the following structural BVDV Ags: Erns, E1, and E2 glycoproteins. In addition, from nonstructural BVDV Ags Npro, NS2-3, NS4A-B, and NS5A-B, 20 CD8+ T cell epitopes were identified. The majority of these IFN-γ-inducing CD8+ T cell epitopes were found to be highly conserved among more than 200 strains from BVDV-1 and -2 genotypes. These conserved epitopes were also validated as cross-reactive because they induced high recall IFN-γ+CD8+ T cell responses ex vivo in purified bovine CD8+ T cells isolated from BVDV-1- and -2-immunized cattle. Altogether, 28 bovine MHC class I-binding epitopes were identified from key BVDV Ags that can elicit broadly reactive CD8+ T cells against diverse BVDV strains. The data presented in this study will lay the groundwork for the development of a contemporary CD8+ T cell-based BVDV vaccine capable of addressing BVDV heterogeneity more effectively than current vaccines.

Prevalence of bovine abortion, calf mortality, and bovine viral diarrhea virus (BVDV) persistently infected calves among pastoral, peri-urban, and mixed-crop livestock farms in central and Northwest Ethiopia

BackgroundBovine Viral Diarrhea virus (BVDV) is one of important diseases of cattle worldwide causing economic losses to the cattle industry primarily due to increased premature culling and decreased reproductive performance. The virus can cross the placenta during early pregnancy and result in the birth of persistently infected (PI) calves that are efficient transmitters of BVDV and serving as the primary reservoirs for BVDV. Relatively few studies have focused on understanding BVDV seroprevalence, virus detection, genotyping and its distribution in Africa. Most BVDV research in Ethiopia has involved serologic surveys in adult cattle, rather than the identification of PI calves, despite their role in viral shedding and recurring infections. A cross-sectional study was undertaken in three different livestock production systems of Ethiopia with the objective to estimate the prevalence of bovine abortion, calf mortality, and BVDV persistently infected calves.ResultsEar notch samples (882) collected from calves in 349 households were tested for BVDV antigen using antigen capture enzyme-linked immunosorbent assay (ACE). All samples tested were negative for BVDV antigen. The overall animal level crude abortion and calf mortality prevalence were 4.0% (95% CI: 2.9–5.2) and 9.2% (95% CI: 7.7–11.0) respectively. The lower BVDV PI prevalence may be due to a lower effective contact rate between cattle reared in small-scale extensive production systems in Ethiopia.ConclusionsThis is the first report of BVDV Ag test in Ethiopia and no PI was detected in calves in the study areas. Since BVDV is a disease of great economic importance, this study finding must be interpreted with care since absence of evidence is not evidence of absence and even a single BVDV infected animal can serve as source of infection and contribute to the persistent spread of the virus. Greater attention needs to be given to screening for PI animals through testing large number of animals and culling positive animals. Hence, future research should focus on regions and production systems with high BVDV seroprevalence followed by antigen ELISA or BVDV real-time PCR to detect persistently infected and acutely viremic animals.

A Synthetic Modified Live Chimeric Marker Vaccine against BVDV-1 and BVDV-2.

Bovine viral diarrhea virus (BVDV), a pestivirus which exists in the two distinct species BVDV-1 (syn. Pestivirus A) and BVDV-2 (syn. Pestivirus B), is the causative agent of one of the most widespread and economically important virus infections in cattle. For economic as well as for animal health reasons, an increasing number of national BVDV control programs were recently implemented. The main focus lies on the detection and removal of persistently infected cattle. The application of efficient marker or DIVA (differentiation of infected from vaccinated animals) vaccines would be beneficial for the eradication success in regions with a high BVDV prevalence to prevent fetal infection and it would allow serological monitoring of the BVDV status also in vaccinated farms. Therefore, a marker vaccine based on the cytopathic (cp) BVDV-1b strain CP7 was constructed as a synthetic backbone (BVDV-1b_synCP7). For serological discrimination of vaccinated from infected animals, the viral protein Erns was substituted by the heterologous Erns of Bungowannah virus (BuPV, species Pestivirus F). In addition, the vaccines were attenuated by a deletion within the type I interferon inhibitor Npro protein encoding sequence. The BVDV-2 vaccine candidate is based on the genetic sequence of the glycoproteins E1 and E2 of BVDV-2 strain CS8644 (CS), which were introduced into the backbone of BVDV-1b_synCP7_ΔNpro_Erns Bungo in substitution of the homologous glycoproteins. Vaccine virus recovery resulted in infectious cytopathic virus chimera that grew to titers of up to 106 TCID50/mL. Both synthetic chimera BVDV-1b_synCP7_ΔNpro_Erns Bungo and BVDV-1b_synCP7_ΔNpro_Erns Bungo_E1E2 BVDV-2 CS were avirulent in cattle, provided a high level of protection in immunization and challenge experiments against both BVDV species and allowed differentiation of infected from vaccinated cattle. Our study presents the first report on an efficient BVDV-1 and -2 modified live marker vaccine candidate and the accompanying commercially available serological marker ELISA system.

Veterinarians' Knowledge, Attitudes and Practices Associated with Bovine Viral Diarrhoea Virus Control and Prevention in South-East Australia.

Simple SummaryBovine Viral Diarrhoea Virus is a disease of cattle that causes production losses. Despite the virus being widespread across Australia, there are no government or industry-led programs to mitigate the impacts or eliminate Bovine Viral Diarrhoea Virus. Veterinarians were surveyed about their knowledge, attitudes and recommended practices regarding Bovine Viral Diarrhoea Virus and its control. We found that veterinarians’ knowledge of Bovine Viral Diarrhoea Virus in their region is limited, and their attitudes and recommendations for controlling the virus do not always align with those of producers. For example, veterinarians are concerned about the welfare and potential for disease spread associated with control measures involving persistently infected cattle, including a previously undocumented practice in which producers administer blood from persistently infected cattle into naïve cattle as a form of vaccination. This study highlights that a greater understanding of producers’ and veterinarians’ values is needed before Bovine Viral Diarrhoea Virus control could be implemented at a regional or country level.In Australia, the responsibility and associated costs for the control and prevention of Bovine Viral Diarrhoea Virus (BVDV) rest solely with producers. Veterinarians provide producers with farm-specific options for BVDV management and support BVDV control and elimination in their region. We surveyed veterinarians to determine their knowledge, attitudes and practices (KAP) associated with BVDV control in south-east Australia. We found that veterinarians’ recommendations do not always align with producers’ control measures. Veterinarians were uncertain about BVDV prevalence and the proportion of producers using BVDV control measures in their regions. Veterinarians generally promoted biosecurity and vaccination, and were concerned about the welfare and additional disease risks associated with persistently infected (PI) cattle. Veterinarians highlighted concerns about disease risks associated with a previously undocumented practice in which producers collect blood from PI cattle to administer to BVDV naïve cattle; termed “vampire vaccination” in this study. A greater understanding of the burden, impact and economics of BVDV is needed to align veterinarians’ and producers’ KAP to improve BVDV management on farms, and more appreciation of veterinarians’ and producers’ values is needed before BVDV control could be implemented at a regional or country level.

Prevalence and risk factors of bovine viral diarrhea in Colombian cattle.

Background and Aim:Bovine viral diarrhea virus (BVDV) is present in most cattle-raising countries around the world, and it has a negative economic impact in cattle herds. In Colombia, previous studies have estimated the prevalence of BVDV in specific locations. The aim of this study was to estimate the prevalence of BVDV in cattle herds located at several municipalities across the country and to identify the associated risk and protective factors.Materials and Methods:A cross-sectional study was carried out to investigate the prevalence of BVDV in Colombian cattle populations at farm and animal-levels. A total of 387 herds and 8110 animals located in seven different departments were included in this study.Results:An animal- and farm-level prevalence of 36% and 69%, respectively, were estimated. A high variation for the farm-level prevalence was found among the municipalities studied. Moreover, seropositive cattle to the infectious bovine rhinotracheitis virus (odds ratio (OR)=2.38, p=0.0479) and Neospora caninum (OR=3.15, p=0.0122) were more likely to be seropositive for BVDV, while the practice of burning dead animals at the farm was identified as a protective factor (OR=0.17, p=0.014).Conclusion:The prevalence of BVDV varied more at farm-level compared to animal-level. Two risk factors and one protective factor were identified. The results of the current study are essential to understand the epidemiology of BVDV in Colombia, and to formulate strategies in the region to mitigate the impact of this virus on the productive and reproductive indicators of cattle farms at the regional level.

Genetic analysis of bovine viral diarrhea virus in pre-weaned native Korean calves.

Bovine viral diarrhea virus (BVDV), a prominent viral pathogen worldwide, causes substantial economic losses in the cattle industry. BVDV comprises two recognized species, BVDV-1 and BVDV-2, and at least 21 subtypes (1a-1u) for BVDV-1 and four subtypes (2a-2d) for BVDV-2 based on its 5'-untranslated region. This study aimed at investigating the prevalence and genetic analysis of BVDV in calf feces in the Republic of Korea (ROK). We collected fecal samples from 635 pre-weaned native Korean calves aged 1-60days, regardless of diarrhea, and subjected them to RT-PCR and phylogenetic analysis. Thirty-five (5.5%) of the 635 samples were positive for BVDV infection. BVDV was detected in 20, 10, and 5 calves aged 1-20days, 21-40days, and 41-60days, respectively. BVDV was the most frequent in 17 normal feces, followed by 16 diarrheic feces, and 2 hemorrhagic feces. Phylogenetic analysis revealed that 25 samples belonged to BVDV-1b; 1 sample, BVDV-1c; and 9 samples, BVDV-2a. Moreover, the BVDV-1b and BVDV-2a isolates showed genetic variations. BVDV-1b was detected in diarrheic, hemorrhagic, and normal fecal samples. Thus, BVDV-1b is the most prevalent in calves and causes enteric disease with differing severity. BVDV-1c was newly identified in diarrheic calves. Further studies are warranted to elucidate the pathogenesis of BVDV-1c infection and its clinical manifestations. Our results indicate that effective vaccines and control programs against BVDV are required in the ROK.

Assessment of the cost effectiveness of compulsory testing of introduced animals and bulk tank milk testing for bovine viral diarrhea in Japan.

Bovine viral diarrhea (BVD) is a chronic disease of cattle caused by infection with BVD virus (BVDV) and can result in economic losses within the livestock industry. In Japan, the test and culling policy is a basic control measure, and implementation of an adequate vaccination program is recommended as a national policy. In addition, optional control measures, including compulsory testing of introduced animals and bulk tank milk (BTM) testing as a mass screening method, are used in several provinces, but their efficacy has not been completely assessed. We evaluated these control measures using the scenario tree model of BVD in Japan, developed in the previous study. The model outputs indicated that compulsory testing of all introduced cattle, rather than only heifers and/or non-vaccinated cattle, was cost effective and reduced the risk of BVDV introduction due to animal movement and that BTM testing could effectively monitor most part of the cattle population. Vaccination coverage and BVDV prevalence among introduced cattle could also affect the cost effectiveness of compulsory testing of targeted cattle, particularly under low vaccination coverage or high BVDV prevalence. However, even with the implementation of a highly effective monitoring scheme for many years, BVD risk could not be eliminated; it instead converged at a very low level (0.02%). Disease models with a cost-effective output could be a powerful tool in developing a control scheme for chronic animal diseases, including BVD, with the consent of relevant stakeholders.

An epidemiological survey of bovine viral diarrhea infection in calves in Egypt with identification of high prevalence of persistent infected animals

In the present study, we identified the persistent infection by bovine viral diarrhea virus (BVDV) in 45 clinically suspected persistent infected (PI) calves and 260 apparently healthy calves from Damietta governorate (North) in Egypt during 2016 using enzyme-linked immunosorbent assay (ELISA), serum neutralization test (SNT), immunohistochemistry (IHC), and reverse transcription polymerase chain reaction (RT-PCR). The identification of PI calves was performed after vaccination by CattleMaster® 4. The age of PI calves in the current study was ranged from 2 to 4 months (n = 7) and from 5 to 8 months (n = 38). ELISA revealed the infection in 4 clinically suspected PI calves (57.14%) aged 2 to 4 months. While the infection did not approve in any of the calves within this age using RT-PCR, for calves aged from 5 to 8 months old, ELISA showed the infection in 30 calves (78.94%), and from these calves, the infection was confirmed in 6 calves (15.79%) only using RT-PCR. For apparently clinically healthy animals, 11 transiently infected calves were identified by IHC (positive), SNT (positive), and RT-PCR (negative) at 2 months’ post-vaccination. Collectively, the persistent infection was confirmed in 9 calves (2.95%) out of 305 calves. In summary, our study detected a high prevalence of PI calves with BVDV in Damietta province in Egypt, which highlights the importance of introducing effective prevention and control strategies throughout Egypt to minimize the prevalence of BVDV.

A meta-analysis of bovine viral diarrhoea virus (BVDV) prevalences in the global cattle population

A random effect meta-analysis was performed to estimate the worldwide pooled bovine viral diarrhoea virus (BVDV) prevalences of persistently infected (PI), viraemic (VI) and antibody-positive (AB) animals and herds. The meta-analysis covered 325 studies in 73 countries that determined the presence or absence of BVDV infections in cattle from 1961 to 2016. In total, 6.5 million animals and 310,548 herds were tested for BVDV infections in the global cattle population. The worldwide pooled PI prevalences at animal level ranged from low (≤0.8% Europe, North America, Australia), medium (>0.8% to 1.6% East Asia) to high (>1.6% West Asia). The PI and AB prevalences in Europe decreased over time, while BVDV prevalence increased in North America. The highest mean pooled PI prevalences at animal level were identified in countries that had failed to implement any BVDV control and/or eradication programmes (including vaccination). Our analysis emphasizes the need for more standardised epidemiological studies to support decision-makers implementing animal health policies for non-globally-regulated animal diseases.

A systematic review and meta-analysis of the epidemiology of bovine viral diarrhea virus (BVDV) infection in dairy cattle in China

Bovine viral diarrhea virus (BVDV) infection causes significantly economic losses to cattle industry worldwide, also including China. The epidemiological prevalence of infection associated with BVDV in dairy cattle has not been systematically assessed in China. Therefore, we undertook this study to evaluate prevalent of BVDV infection. We conducted a systematic review and meta-analysis of data from papers on the BVDV incidence and prevalence in dairy cattle in China by searching China Science and Technology Journal Database, China National Knowledge Infrastructure (CNKI), Wan Fang Database and PubMed for publication from March 2003 to March 2018. The 41 studies reporting the prevalence of BVDV in cattle in China were selected upon our inclusion criterion. The pooled BVDV prevalence in dairy cattle in China was estimated to 53.0% (95% CI 40.2–65.7) based on the data obtained from the 27,530 cows tested using serological or virological assay in the qualified papers published during the periods (χ² = 51,861.0, I2 = 99.9%). The highest BVDV positive rate in dairy flocks reached 90.0% in Fujian province of China, followed by Shaanxi (88.9%) and Shandong (83.3%). The prevalence in the six administrative districts of China was validated to be highly variable (25.7%–72.2%) and reached 72.2% in dairy cattle flocks of Northern China. Besides, the BVDV-RNA positive rate was estimated 27.1% (95% CI 17.3–37.0) based on 6 studies, comparatively, the pooled BVDV seroprevalence based on 35 studies was about 57.0% (95% CI 44.4–69.5) in China. This systematic review and meta-analysis firstly established an estimated prevalence of BVDV in dairy herds in China, indicating that the BVDV infection is escalating, though there is a bias in the number of studies between 2003–2009 and 2010–2018 timescales. This study may help understand the status of BVDV infection in dairy herds in China. Further extensive and comprehensive investigation is recommended, and effective intervention measures for preventing and controlling BVDV spread in dairy herds should be deployed, especially herds that have been exposed to BVDV.

Spatial and risk factor analysis of bovine viral diarrhoea (BVD) virus after the first-year compulsory phase of BVD eradication programme in Northern Ireland

Bovine viral diarrhoea virus (BVDV) causes bovine viral diarrhoea (BVD), which is a contagious pathogen that can have a significant economic impact on cattle industries. In Northern Ireland (NI), the compulsory phase of a BVD eradication programme was implemented in 2016. The aim of this retrospective population based study was to utilize herd-level data after the first year of the compulsory phase (March 2016–March 2017) to determine the spatial distribution and variation of BVDV, to identify clusters of infection, and to quantify some risk factors associated with BVD in NI. Global spatial clustering (autocorrelation) and local spatial hot-spot analyses were used to specify the clustering areas (hot- and cold-spot). A suite of multivariable logistic analyses was performed to estimate the associations of spatial and non-spatial factors (relating to herd characteristics) with the risk of being a BVDV positive herd. Final models were compared by evaluating the model fit and the ability to account for spatial autocorrelation in the study area. There were 17,186 herds included in the analysis. The herd-level prevalence of BVDV was 11.31%. Significant spatial clustering of BVDV positive herds was presented in the central region of NI. A mixed effects logistic model, with a spatial random effect term, was considered the best model. The final model showed that a positive BVDV status during the voluntary phase prior to the compulsory phase started (OR = 2.25; CI 95% = 1.85–2.73), larger herd size (OR = 6.19; CI 95% = 5.22–7.34 for herd size > 100 animals) and a larger number of positive nearest neighbours within 4 km radius (OR = 1.24; CI 95% = 1.05–1.47 for 8–9 neighbours and OR = 1.41; CI 95% = 1.20–1.65 for 10–12 neighbours) were significantly related to the risk of a herd being tested positive for BVDV. The clear spatial pattern from the local spatial clustering analyses could be used for targeted surveillance and control measures by focusing on the central region of NI.