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Preventive Veterinary Medicine
Elsevier
Preventive Veterinary Medicine

Elsevier

0167-5877

Preventive Veterinary Medicine/Journal Preventive Veterinary MedicineSCIISTP
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    Spatial and seasonal analysis and geovisualization of Fasciola hepatica-free bovine bacillary hemoglobinuria outbreaks in eastern Uruguay, 1999-2019

    Dutra, F.Navarro, M.Romero, A.Briano, C....
    11页
    查看更多>>摘要:Bovine bacillary hemoglobinuria (BBH) produced by Clostridium novyi type D, is an endemic, highly fatal disease of cattle in the temperate grassland region of eastern Uruguay. A previous study showed that in this region, BBH is not associated with Fasciola hepatica or any other known focal-ischemic liver injury, so the reasons for its high incidence remains undetermined. The objective of this study was to analyze data from 45 Fasciola hepatica-free BBH outbreaks (1999-2019) in order to find common animal, seasonal and/or geographical risk factors, which may explain the occurrence of the epizootics. Fisher's goodness-of-fit testing showed a significantly higher case proportion of adult cows (N = 368, 80.5%) and lower of calves (N =8, 1.8%), as compared to the expected proportions of the censused population in the study area and historical submissions computed from the laboratory database (Chi-Sq = 346.2 and 174.8, df = 7, P < 0.00). Time series decomposition showed a bi-seasonal pattern, with a larger peak in spring and early summer (October to January) and a smaller increase in autumn (March-May). The lowest seasonal indices were on mid-summer (February) and winter (June-September). A combination of spatial statistics was used to assess the different spatial features of the disease and consistency of the findings. Global spatial autocorrelation showed BBH was significantly clustered (Moran's I = 0.407, P < 0.001). Both smoothed Anselin's Local Indicator of Spatial Autocorrelation and Kulldorff's spatial scan Poisson and Bernoulli models, detected roughly the same high-risk areas in the southeastern part of the Merin Lagoon basin, with the most likely cluster centered in the large wetland biosphere reserve "Eastern Wetlands and Coastal Strip" (RR = 9.12, P < 0.001). Outbreaks were georeferenced (latitude, longitude) and thematic dotmapping geovisualization in Google EarthTM showed that the results were robust and truly geographic in nature. Most outbreaks (40/45, 88.8%) occurred on wetlands areas and large river valleys, characterized by poorly drained and frequently flooded soils, indicating that moisture-laden soils are the natural habitat of C. novyi type D. Grasslands in these endemic areas support rapid fattening of cattle during spring-summer, and somewhat less in autumn, in almost exact correspondence with BBH peaks, suggesting a close causal association in high-risk areas. Risk is significantly higher in adult cows probably because the spore content in the liver is highest in this category. The altered lipid metabolism and lipotoxicity in the liver may be the precipitating factor for spore germination and epizootic occurrence.

    The impact of the epidemic experience on the recovery of production of pig farmers after the outbreak-Evidence from the impact of African swine fever (ASF) in Chinese pig farming

    Ge XuSarkar, ApurboLu QianZhang Shuxia...
    15页
    查看更多>>摘要:The African swine fever (ASF) has triggered considerable shocks to the pig farming industry, which has become a significant animal disease epidemic. The study explores the effect of epidemic experience on post-outbreak production recovery from resilience and risk perception based on 340 micro-survey data from Sichuan, Henan, and Shandong provinces. Epidemic experience has been shown to impact the degree of post-outbreak production recovery positively, and farmers who have endured epidemics are more likely to recover their production after outbreaks. The mechanistic study indicates that past epidemics in African swine fever shocks can effectively improve farmers' cognitive resilience and management capability, enhance recovery, and reduce risk perception in the aftermath of production recovery. In order to alleviate the endogenous problems caused by selection bias, missing variables, and two-way causality. This paper uses factor analysis to comprehensively measure production recovery capacity and production risk perception, and uses propensity score matching(PSM), instrumental variable method and replacement measurement methods to conduct robustness tests, and find the conclusions are still robust. The empirical analysis shows that the experience of the epidemic will promote the recovery of farmers after the outbreak; the experience of the epidemic will significantly impact the recovery of production after the outbreak for both free-range and professional farmers.

    Factors associated with antimicrobial use in pig and veal calf farms in the Netherlands: A multi-method longitudinal data analysis

    Mallioris, PanagiotisDohmen, WietskeLuiken, Roosmarijn E. C.Wagenaar, Jaap A....
    10页
    查看更多>>摘要:Minimizing antimicrobial use (AMU) in livestock is needed to control antimicrobial resistance (AMR). In the Netherlands, the livestock sector reduced AMU by almost 70 % since 2009, but this reduction stagnated in recent years. With only therapeutic AMU allowed, it is clear that besides socio-economic and behavioral factors, also the farm technical characteristics influence the conditions under which farmers need AMU. These characteristics pertain to farm management, including biosecurity, vaccination schemes, nutrition, micro-climate and husbandry practices. Identifying farm-related risk factors for AMU is needed to control AMR in a sustainable and pragmatic way. This need, often concerns the overall contribution of seemingly related (rather than individualized) factors. Here, risk factors for AMU in pig and calf farms were determined using two approaches: a typical risk factor analysis based on generalized estimating equations (GEEs) or hierarchical mixed-effects models and a multiblock partial least-squares regression analysis. These methods were applied to longitudinal data from two previous studies, i.e. a panel study and an intervention study involving 36 multiplier pig farms and 51 veal calf farms in the Netherlands, respectively. The multiblock analysis allowed us to quantify the importance of each factor and their respective block (i.e. farm management domain). For pigs, factors related to internal biosecurity had the highest impact on AMU, while for calves, these were mainly related to micro-climate. Structural characteristics, such as farm size and production type, followed in importance for both sectors. While both methods provided similar outcomes, the multiblock approach provided further insights by grouping and comparing factors believed to be inter-related.

    Bayesian estimation of prevalence of Johne's disease in dairy herds in Southern Italy

    Sposato, AlessioFanelli, AngelaCordisco, MarcoTrotta, Adriana...
    5页
    查看更多>>摘要:Johne's disease (JD) is a chronic granulomatous disease caused by Mycobacterium avium subsp. paratuberculosis (MAP) causing important losses on dairy farms. In Italy, voluntary programs to control MAP infection in dairy cattle are implemented in the Northern part of the country, where several studies have been carried out. Conversely, the disease status has not been fully investigated in the Southern regions. The aims of this study were to (i) determine the herd-level true prevalence (HTP) and (ii) the conditional within herd animal-level prevalence (CWHP) of JD in selected dairy cattle herds in Southern Italy. Serum samples were taken from 27 farms and analysed using a commercial ELISA test. A Bayesian model was fitted to the data. The estimated posterior mean of HPT was 0.46 (89 % CI 0.25-0.67), while the mean CWHP was 0.03 (89 % CI: 0.012-0.045). The results presented in this study call for designing and implementing an effective JD control program at national level.

    Novel reassortment 2.3.4.4b H5N8 highly pathogenic avian influenza viruses circulating in Xinjiang, China

    Chang, NanaZhang, ChengMei, XindiDu, Fei...
    7页
    查看更多>>摘要:In 2016, H5N8 avian influenza viruses of clade 2.3.4.4b were detected at Qinghai Lake, China. Afterwards, the viruses of this clade rapidly spread to Asia, Europe, and Africa via migratory birds, and caused massive deaths in poultry and wild birds globally. In this study, four H5N8 isolates (abbreviated as 001, 002, 003, and 004) were isolated from the live poultry market in Xinjiang in 2017. Phylogenetic analysis showed that the hemagglutinin genes of the four isolates belonged to clade 2.3.4.4b, while the viral gene segments were from multiple geographic origins. For 002, the polymerase acidic gene had the highest sequence homology (99.55 %) with H5N8 virus identified from green-winged teal in Egypt in 2016, and the remaining genes exhibited the highest sequence homologies (99.18-100 %) with those of H5N8 viruses isolated from domestic duck sampled in Siberia in 2016. The polymerase basic 1 gene clustered together with H5N8 virus identified from painted stork of India in 2016, and the remaining genes had relatively close genetic relationships with H5N8 viruses identified from the duck of Siberia in 2016 and turkey in Italy in 2017. For the other three isolates, the nucleoprotein gene of 001 had the highest sequence homology (98.82 %) and relatively close genetic relationship with H9N2 viruses identified from poultry in Vietnam and Cambodia in 2015-2017, and all the remaining genes had the highest sequence homologies (99.18 %-99.58 %) and relatively close genetic relationships with H5N8 viruses identified from poultry and waterfowl sampled in African countries in 2017 and swan sampled in China in 2016. Multiple basic amino acids were observed at cleavage sites in the hemagglutinin proteins of the H5N8 isolates, indicating high pathogenicity. In addition, the L89V, G309D, R477G, I495V, A676T and I504V mutations in the polymerase basic 2 protein, N30D and T215A mutations in the matrix 1 protein, P42S mutation, and 80-84 amino acid deletion in the nonstructural 1 protein were detected in all isolates. These mutations were associated with increased virulence and polymerase activity in mammals. Therefore, our results indicate that the H5N8 isolates involved multiple introductions of reassorted viruses, and also revealed that the wetlands of Northern Tianshan Mountain may play a key role in H5N8 AIVs disseminating among Central China, the Eurasian continent, and East African Countries.

    Spatial and temporal patterns of white spot disease in Rayong Province, Thailand, from october 2015 to september 2018

    Yaemkasem, SompitBoonyawiwat, VisanuSukmak, ManakornThongratsakul, Sukanya...
    6页
    查看更多>>摘要:This study aimed to analyze the spatial and temporal patterns of white spot disease (WSD) in shrimp farms in Rayong Province, Thailand, between October 2015 and September 2018. The longitudinal data of all active shrimp farms were collected and categorized into two groups: cases and non-cases. A space-time permutation scan, epidemic curve, and time-series analysis were used to evaluate the spatiotemporal patterns. We assessed a total of 1126 ponds across 176 farms in two districts (Klaeng and Mueang Rayong) and identified three significant (P < 0.05) clusters of WSD cases. The biggest cluster encompassed 21 geographical coordinates. This cluster had a radius of 1.14 km and occurred between January 31, 2017, and February 28, 2017. The epidemic curve showed that the biggest outbreak peaked from December 2017 to February 2018. In the time-series analysis, the highest probability of actual WSD cases was at the beginning of each calendar year, consistent with the prominent high probability recorded in WSD forecasts. Our analysis presents the interaction between hotspot areas and time period. These results should help the relevant authorities implement appropriate surveillance programs and control measures to limit the occurrence and transmission of WSD.

    Antibody response to rabies pre-exposure vaccination among village health volunteers in a northern region of Thailand

    Khamduang, WoottichaiHongjaisee, SayamonPothita, TippayathidaKongyai, Natedao...
    5页
    查看更多>>摘要:Background: Rabies is a lethal, however the disease is preventable through vaccination either before or immediately after an exposure. This study aimed to provide a pre-exposure prophylaxis rabies immunization to village health volunteers (VHV) who provide rabies vaccination for pets and free-roaming dogs in their villages and evaluate the antibody level and adverse effects after vaccination. We also assessed the knowledge related to rabies of these VHVs before field trip for pet vaccination. Methods: This study was conducted at Mae Kha sub district, San Pa Tong district, Chiangmai, Thailand between January and March 2020. Consenting participants were interviewed using a questionnaire, received an intradermal two-dose, seven-day pre-exposure rabies vaccination, and sera were tested for anti-rabies antibody levels with the cost effective easy competitive enzyme-linked immunosorbent assay (CEE-cELISA) before and after vaccination. Results: A total of 27 VHVs were recruited from 14 villages in Mae Kha sub district. All of them were male and had a median age of 61.5 years (interquartile range: 55-64). After vaccination, seroconversion rate was 92 % (23/25) with a median of 12.4 EU/mL (interquartile range: 8.9-20.1). Two participants who had rabies vaccination one year previously still had adequate levels before receiving a booster dose. All participants did not show any serious adverse reactions after vaccination. Conclusion: A regimen of two-dose, seven-day vaccination series in high-risk health volunteers using an intradermal administration provides a high seroconversion rate, efficacy and safe for pre-exposure vaccination schedule. In addition, rabies-related knowledge should be provided to village health volunteers before their fieldwork.

    Alone or a combination: Ascertaining factors associated with choice of pig health management strategies amongst smallholder farmers in northern Uganda

    Ndyomugyenyi, Elly KurobuzaOwiny, David OkelloOkello, Daniel MichealAliro, Tonny...
    11页
    查看更多>>摘要:Pig production is an important farm enterprise for an increasing number of smallholder farmers due to its potential for improving household incomes. The sector is however faced with high burden of health issues that limit most farmers from realizing the benefits. In order to improve management of pig health for smallholder farmers, an understanding of the major health issues and factors associated with farmers' choice of the pig health management strategies are paramount. Using a cross-sectional survey of 240 smallholder pig farmers in northern Uganda, this study assessed the factors associated with the use of different pig health management practices adopted by smallholder pig farmers. Data analysis involved descriptive statistics and two different regression models. Binary Probit Regression model was used to assess factors associated with the use of a single pig health management strategy, while, Generalized Poisson Regression model was used to assess the factors associated with the number of pig health management strategies used by the farmers. Results showed that the common health issues were African Swine Fever, lice, worms and mange, while the common strategies for health management involved self-administering antibiotics, consulting veterinarians, deworming, spraying with acaricides, selling the sick pigs, treatment with local herbs, and burying dead pigs. These pig health management strategies were influenced by farmers location, experience, age, access to extension, use of information and communication technologies, and use of processed feeds. This study recommends improving farmers' access to relevant infor-mation and expanding veterinary extension services by promoting the use of radio and mobile phones in pig health management.

    Preventive effect of on-farm biosecurity practices against highly pathogenic avian influenza (HPAI) H5N6 infection on commercial layer farms in the Republic of Korea during the 2016-17 epidemic: A case-control study

    Yoo, Dae-SungLee, Kwang-NyeongChun, Byung-ChulLee, Ho-Sung...
    10页
    查看更多>>摘要:Highly pathogenic avian influenza virus (HPAIv) H5N6 has destructive consequences on the global poultry production system. Recently, a growing number of layer farms have been heavily damaged from the HPAIv epidemic due to the increased virulence of the virus and the intensification of the production system. Therefore, stakeholders should implement effective preventive practices at the farm level that are aligned with contingency measures at the national level to minimize poultry losses. However, numerous biosecurity protocols for layer farm workers to follow have been developed, impeding efficient prevention and control. Furthermore, the effectiveness of biosecurity practices varies with the geographical condition and inter-farm contact structures. Hence, the objective of our study was to examine the preventive effect of five biosecurity actions commonly practiced at layer farms in the Republic of Korea against HPAIv H5N6: (i) fence installation around a farm, ii) rodent control inside a farm; iii) disinfection booth for visitors for disinfection protocols, iv) an anterior room in the sheds before entering the bird area and v) boots changes when moving between sheds in the same farm. We conducted a case-control study on 114 layer case farms and 129 layer control farms during the 2016-17 HPAI epidemic. The odds ratios for five on-farm biosecurity practices implemented in those study groups were estimated as a preventive effect on the HPAI infection with covariates, including seven geographical conditions and three network metrics using Bayesian hierarchical logistic regression and geographical location weighted logistic regression. The results showed that the use of a disinfection booth for personnel reduced the odds of HPAIv H5N6 infection (adjusted odds ratio [AOR] = 0.002, 95 % credible interval [CrI] = 0.00007 - 0.025) with relatively small spatial variation (minimum AOR - maximum AOR: 0.084-0.263). Changing boots between sheds on the same farm reduced the odds of HPAIv H5N6 infection (AOR = 0.160, 95 % CrI = 0.024-0.852) with relatively wide spatial variation (minimum AOR - maximum AOR = 0.270-0.688). Therefore, enhanced personnel biosecurity protocols at the farm of entry for layer farms is recommended to effectively prevent and respond to HPAIv H5N6 infection under different local condition. Our study provides an important message for layer farmers to effectively implement on-farm biosecurity actions against HPAIv H5N6 infection at their farms by setting priorities based on their spatial condition and network position.

    Machine learning classification methods informing the management of inconclusive reactors at bovine tuberculosis surveillance tests in England

    Romero, M. PilarChang, Yu-MeiBrunton, Lucy A.Parry, Jessica...
    12页
    查看更多>>摘要:Bovine tuberculosis (bTB) remains one of the most complex, challenging, and costly animal health problems in England. Identifying and promptly removing all infected cattle from affected herds is key to its eradication strategy; the imperfect sensitivity of the diagnostic testing regime remaining a serious obstacle. The main diagnostic test for bTB in cattle in England, the Single Intradermal Comparative Cervical Tuberculin Test (SICCT: also known as the skin test), can produce inconclusive results below the reactor threshold. The immediate isolation of inconclusive reactor (IR) animals followed by a 60-day retest may not prevent lateral spread within the herd (if it is substandard, allowing transmission) or transmission to wildlife. Over half of IRonly herds that went on to have a positive skin test result (a bTB herd 'incident') in 2020, had it triggered by at least one IR not clearing their 60-day retest, instead of by another test within the previous 15 months. Machine learning classification algorithms (classification tree analysis and random forest), applied to England's 2012-2020 IR-only surveillance herd tests, identified at-risk tests for an incident at the IRs' 60-day retest. In this period, 4 739 out of 22 946 (21 %) IR-only surveillance tests disclosing 6 296 out of 42 685 total IRs, had an incident at retest (2 716 IRs became reactors and 3 580 IRs became two-time IRs). Both models showed an AUC above 80 % in the 2012-2019 dataset. Classification tree analysis was preferred due to its easy-to-interpret outputs, 70 % sensitivity, and 93 % specificity in the 20 % of 2019-2020 testing dataset. The paper aimed to identify IR-only surveillance tests at-risk of an incident at the 60-day retest to target them with appropriate measures to mitigate the IRs' risk. Sixteen percent (341 out of 2 177) of IR-only herd tests were identified as high-risk in the 2020 dataset, with 265 (78 %) of these having at least one reactor or IR at retest. Severe-level reinterpretation of the high-risk IR-only disclosing tests identified in this dataset would turn 68 out of the 590 (12 %) IRs into reactors, generating 23 incidents, the majority (19 or 83 %) part of the 265 incidents that would have been declared at the retest. Classification tree analysis used to identify IR-only high-risk tests in herds eligible for severe interpretation would enhance the sensitivity of the test-and-slaughter regime, cornerstone of the bTB eradication programme in England, further mitigating the risk of disease spread posed by IRs.