Determination of the sensitivity and specificity of bovine tuberculosis screening tests in dairy herds in Thailand using a Bayesian approach.

BACKGROUND: The objective of this study was to determine the sensitivity (Se) and specificity (Sp) of bovine tuberculosis (bTB) screening tests including a single intradermal tuberculin (SIT) test, interferon gamma (IFN-γ) assay, and a commercial ELISA test (M. bovis Ab) in dairy cattle, under field conditions, using a Bayesian approach. RESULTS: The study population consisted of 128 dairy cows from 25 bTB-infected herds in Chiang Mai and Chiang Rai provinces, Thailand. A single-population Bayesian model was implemented assuming conditional dependence between the SIT test and IFN-γ assays. The 95% posterior probability interval (PPI) of the SIT test (severe interpretation) Se ranged from 75.3 to 95.2% (median = 87.6%), while the Sp was slightly lower (median = 83.6%, PPI = 74.2-92.8%). The IFN-γ assay Se was moderate and the 95% PPI ranged from 38.6 to 74.4% (median = 55.7%) with higher Sp (median = 93.5.4%, PPI = 87.0-98.1%). The M. bovis Ab ELISA Se was low, with 95% PPI ranging between 30.0 and 71.2% (median = 47.4%); however, the Sp was high (median = 90.9%, PPI = 84.5-95.5%). CONCLUSION: The SIT test sensitivity was similar to that demonstrated in other regions and can, therefore, be used effectively as part of control programs in this area. The IFN-γ and M. bovis Ab ELISA assays can be applied as supplementary techniques. The test performance of these tests when used as single tests without confirmation, however, are expected to continue to challenge disease eradication efforts.

Cost-benefit analysis of vaccination against Mycobacterium avium ssp. paratuberculosis in dairy cattle, given its cross-reactivity with tuberculosis tests.

Johne's disease (JD), or paratuberculosis, is a chronic enteric disease of ruminants, caused by infection with Mycobacterium avium ssp. paratuberculosis (MAP). Johne's disease causes considerable economic losses to the US dairy industry, estimated to be over $200 million annually. Available control strategies include management measures to improve calf hygiene, test-and-cull strategies, and vaccination. Although the first 2 strategies have shown to reduce the prevalence of MAP, they require dedicated and long-term efforts from dairy producers, with often relatively slow progress. As a result, uptake of both strategies has not been as wide as expected given the economic benefits especially of improved hygiene. Vaccination has also been found to reduce the prevalence and economic losses of JD, but most economic estimates have been based on simulation of hypothetical vaccines. In addition, if an animal is vaccinated, cross-reactivity between MAP antibodies and bovine tuberculosis (BTB) antigens may occur, decreasing the specificity of BTB tests. Therefore, MAP vaccination would cause additional indirect costs to the BTB surveillance and control program. The objective of the present study was to use data from a MAP vaccine trial together with an epidemiologic and economic model to estimate the direct on-farm benefits of MAP vaccination and to estimate the indirect costs of MAP vaccination due to the cross-reactivity with BTB tests. Direct economic benefits of MAP vaccination were estimated at $8.03 (90% predictive interval: -$25.97 to $41.36) per adult animal per year, all accruing to the dairy producers. This estimate is likely an underestimation of the true direct benefits of MAP vaccination. In addition, indirect economic costs due to cross-reactivity were $2.14 per adult animal per year, making MAP vaccination economically attractive. Only in regions or states with a high frequency of BTB testing (because of, for example, Mycobacterium bovis outbreaks in a wild deer population) and areas where typically small groups of animals are BTB tested would MAP vaccination not be economically attractive.

Exploring the influence of slaughterhouse type and slaughtering steps on Campylobacter jejuni contamination in chicken meat: A cluster analysis approach.

Campylobacter jejuni (C. jejuni), a foodborne pathogen, poses notable hazards to human health and has significant economic implications for poultry production. This study aimed to assess C. jejuni contamination levels in chicken carcasses from both backyard and commercial slaughterhouses in Chiang Mai province, Thailand. It also sought to examine the effects of different slaughtering practices on contamination levels and to offer evidence-based recommendations for reducing C. jejuni contamination. Through the sampling of 105 chicken carcasses and subsequent enumeration of C. jejuni, the study captured the impact of various slaughtering practices. Utilizing k-modes clustering on the observational and bacterial count data, the research identified distinct patterns of contamination, revealing higher levels in backyard operations compared to commercial ones. The application of k-modes clustering highlighted the impact of critical slaughtering practices, particularly chilling, on contamination levels. Notably, samples with the lowest bacterial counts were typically from the chilling step, a practice predominantly found in commercial facilities. This observation underpins the recommendation for backyard slaughterhouses to incorporate ice in their post-evisceration soaking process. Mimicking commercial practices, this chilling method aims to inhibit C. jejuni growth by reducing carcass temperature, thereby enhancing food safety. Furthermore, the study suggests backyard operations adopt additional measures observed in commercial settings, like segregating equipment for each slaughtering step and implementing regular cleaning protocols. These strategic interventions are pivotal in reducing contamination risks, advancing microbiological safety in poultry processing, and aligning with global food safety enhancement efforts.

Herd-level risk factors associated with fecal shedding of Shiga toxin-encoding bacteria on dairy farms in Minnesota, USA.

This study aimed to identify herd-level risk factors associated with fecal shedding of Shiga toxin-encoding bacteria (STB) on dairy cattle farms in Minnesota, USA. After adjustment for farm size, risk factors included: use of total mixed ration (TMR) for lactating dairy cows [odds ratio (OR) = 3.0; 95% confidence interval (CI): 1.8 to 5.1], no use of monensin for weaned calves (OR = 4.8, 95% CI: 2.5, 9.3), and no use of decoquinate for preweaned calves (OR = 2.2, 95% CI: 1.4, 3.6). Fecal shedding of STB was more common in small herds (< 100 cows, OR = 3.6, 95% CI: 2.1, 6.2) than in large herds (≥ 100 cows). Herd management factors related to cattle feeding practices were associated with fecal shedding of STB.

Facteurs de risque au niveau du troupeau associés à l'excrétion fécale des bactéries encodant la toxine de Shiga dans les fermes laitières du Minnesota, États-Unis. Cette étude avait pour but d'identifier les facteurs de risque au niveau du troupeau associés à l'excrétion fécale de bactéries encodant la shiga-toxine dans les fermes de bovins laitiers au Minnesota, États-Unis. Après un ajustement pour la taille de la ferme, les facteurs de risque incluaient : l'utilisation de la ration mixte totale (RMT) pour les vaches laitières en lactation [rapport de cotes (RC) = 3,0; intervalle de confiance (IC) de 95 % : de 1,8 à 5,1], pas d'utilisation de monensin pour les veaux sevrés (RC = 4,8, IC de 95 % : 2,5, 9,3) et pas d'utilisation de décoquinate pour les veaux présevrés (RC = 2,2, IC de 95 % : 1,4, 3,6). L'excrétion fécale de la bactérie encodant la shiga-toxine était plus commune dans les petits troupeaux (< 100 vaches, RC = 3,6, IC de 95 % : 2,1, 6,2) que dans les grands troupeaux (≥ 100 vaches). Des facteurs de gestion du troupeau se rapportant aux pratiques d'alimentation du bétail ont été associés à l'excrétion fécale de la bactérie encodant la shiga-toxine.(Traduit par Isabelle Vallières).

Herd-level risk factors associated with chronic wasting disease-positive herd status in Minnesota, Pennsylvania, and Wisconsin cervid herds.

The objective of this study was to evaluate risks related to introduction of Chronic Wasting Disease (CWD) to farmed cervid herds in Minnesota (MN), Pennsylvania (PA), and Wisconsin (WI). This was the first study to evaluate risk factors related to multiple pathways of CWD transmission to farmed cervid herds. Participating herds in this case-control study included 22 case and 49 control herds identified through participation in the respective mandatory State CWD herd program. Data was voluntarily collected from white-tailed deer (WTD) study herds using a questionnaire and state animal health agency databases. Univariable analyses identified associations between CWD-positive herds and variables representing different transmission pathways, including direct contact with infected farmed cervids (imported from a herd that later tested positive for CWD) odds ratio (OR):7.16, 95 % confidence intervals (CI):1.64-31.21 and indirect contact with infected wild cervids (access of domestic cats to pens or feed storage area) OR:4.07, 95 % CI:1.35-12.26, observed evidence of mammalian scavengers inside or outside of fenceline in the previous 12 months OR:6.55, 95 % CI:1.37-31.32, ≤ 5 km distance to nearest detected CWD-positive wild cervid OR:3.08, 95 % CI:1.01-9.39, forested area crosses the perimeter fenceline OR:3.54, 95 % CI:1.13-11.11, ≤ 0.3 m distance of water source to fenceline OR:4.71, 95 % CI:1.60-13.83, and water source shared with wild cervids (running or standing water) OR:4.17, 95 % CI:1.34-12.92. Three variables from univariable analyses that represented different biological transmission pathways were placed in a Firth's penalized maximum likelihood multivariable logistic regression to evaluate associations between transmission pathway and CWD herd infection status. For the issue of low sample size and overfitting, 95 % CIs for estimated coefficients for the three variables were computed via bootstrapping of 10,000 independent bootstrap samples. The three biological variables were significantly associated with herd CWD infection status: imported cervids from a herd that later tested positive for CWD (OR:5.63; 95 % CI:1.1-28.2), ≤ 0.3 m distance of cervid water source to perimeter fenceline (OR:4.83; 95 % CI:1.5-16.1), and ≤ 5 km distance to nearest detected CWD-positive wild cervid (OR:4.10; 95 % CI:1.1-15.2). The risk factors associated with CWD herd status identified in this study indicated the importance of transmission through direct contact pathways with infected cervid herds (introduction of cervids from herds later identified as CWD-infected) and indirect contact pathways with infected wild cervids that could be related to other animals through the perimeter fence. Further studies are needed to confirm and clarify understanding of indirect pathways to allow development of improved biosecurity practices to prevent CWD introduction to cervid herds.

Examining perceived risk to bovine tuberculosis through factorial survey to inform policymaking for zoonotic diseases control and surveillance.

Prevention and control of infectious diseases in livestock is dependent upon perceived risk and susceptibility, including the prevention of between-herd transmission of bovine tuberculosis through introductions of cattle to susceptible herds. To examine how perceived risk and susceptibility can help to inform policymaking in disease surveillance and control, we used factorial surveys to profile risk perceptions of cattle producers. We found that government indemnity and slaughtering policy did not impact the cattle purchasing behavior of producers who responded to our survey, but rather through other attributes such as the reliability or reputation of the seller. In addition, we identified significant production type and gender differences in purchasing behavior and risk perception. Finally, clustering analysis revealed a group of high-risk respondents characterized as experienced and very dedicated owners of established medium to large size herds. With the increasing availability of business data, assessment of producer's behavior, personalities and attitudes allows policymakers to understand the needs of cattle producers and develop tailored programs that will improve producer cooperation with government agencies.

Analysis of dairy cattle movements in the northern region of Thailand.

Dairy farming in northern Thailand is expanding, with dairy cattle populations increasing up to 8% per year. In addition, disease outbreaks frequently occur in this region, especially foot-and-mouth disease and bovine tuberculosis. Our goal was to quantify the underlying pattern of dairy cattle movements in the context of infectious disease surveillance and control as movements have been identified as risk factors for several infectious diseases. Movements at district levels within the northern region and between the northern and other regions from 2010 to 2017 were recorded by the Department of Livestock Development. Analyzed data included origin, destination, date and purpose of the movement, type of premise of origin and destination, and type and number of moved cattle. Social network analysis was performed to demonstrate patterns of dairy cattle movement within and between regions. The total numbers of movements and moved animals were 3,906 and 180,305, respectively. Decreasing trends in both the number of cattle moved and the number of movements were observed from 2010 to 2016, with increases in 2017. The majority (98%) of the animals moved were male dairy calves, followed by dairy cows (1.7%). The main purpose of the movements was for slaughter (96.3%). Most movements (67.4%) were shipments from central to northern regions, involving 87.1% of cattle moved. By contrast, 56% of the movements for growing and selling purposes occurred within the northern region, commonly involving dairy cows. Constructed movement networks showed heterogeneity of connections among districts. Of 110 districts, 28 were found to be influential to the movement networks, among which 11 districts showed high centrality measures in multiple networks stratified for movement purposes and regions, including eight districts in the northern and one district in each of the central, eastern, and lower northeastern regions of Thailand. These districts were more highly connected than others in the movement network, which may be important for disease transmission, surveillance, and control.

Pooled surveillance testing for asymptomatic SARS-CoV-2 infections at a Veterinary Teaching Hospital College, University of Minnesota, December 2020-April 2021.

To evaluate the use of asymptomatic surveillance, we implemented a surveillance program for asymptomatic SARS-CoV-2 infection in a voluntary sample of individuals at the College of Veterinary Medicine at the University of Minnesota. Self-collected anterior nasal samples were tested using real time reverse transcription-polymerase chain reaction (RT-PCR), in a 5:1 pooled testing strategy, twice weekly for 18 weeks. Positive pools were deconvoluted into individual tests, revealing an observed prevalence of 0.07% (3/4,525). Pooled testing allowed for large scale testing with an estimated cost savings of 79.3% and modeling demonstrated this testing strategy prevented up to 2 workplace transmission events, averting up to 4 clinical cases. At the study endpoint, antibody testing revealed 80.7% of participants had detectable vaccine antibody levels while 9.6% of participants had detectable antibodies to natural infection.

Evaluation of the association between fecal excretion of Mycobacterium avium subsp paratuberculosis and detection in colostrum and on teat skin surfaces of dairy cows.

OBJECTIVE: To evaluate the association between fecal excretion of Mycobacterium avium subsp paratuberculosis (MAP) by dairy cows in the periparturient period and detection of MAP DNA in colostrum specimens and on teat skin surfaces. DESIGN: Cross-sectional study. ANIMALS: 112 Holstein cows. PROCEDURES: Fecal specimens were collected within 48 to 72 hours prior to parturition, and colostrum and teat swab specimens were collected immediately after parturition. Detection of MAP in fecal specimens was performed via microbial culture, and detection of MAP DNA in colostrum and teat swab specimens was achieved via a PCR assay targeting the genetic element ISMAP02. Logistic regression was used to model the relationship between MAP fecal shedding status and detection of MAP DNA in colostrum or teat swab specimens. Population attributable fractions for the proportion of colostrum and teat swab specimens containing MAP DNA were also calculated. RESULTS: The odds of detecting MAP DNA in colostrum or teat swab specimens in cows with MAP-positive (vs negative) fecal specimens were 2.02 and 1.87 respectively. Population attributable fractions estimates suggested that withholding colostrum from MAP-positive cows could reduce the odds of exposing calves to MAP in colostrum by 18.2%. Not permitting natural suckling by calves could reduce the odds of exposing calves to MAP on the teat surfaces of MAP-positive cows by 19.5%. CONCLUSIONS AND CLINICAL RELEVANCE: Results underscored the need for strict adherence to practices that limit contact of calves with adult cows from the time of birth and promote hygienic colostrum handling to avoid possible contamination with MAP during colostrum harvest, storage, or feeding.

Chronic Wasting Disease Transmission Risk Assessment for Farmed Cervids in Minnesota and Wisconsin.

CWD (chronic wasting disease) has emerged as one of the most important diseases of cervids and continues to adversely affect farmed and wild cervid populations, despite control and preventive measures. This study aims to use the current scientific understanding of CWD transmission and knowledge of farmed cervid operations to conduct a qualitative risk assessment for CWD transmission to cervid farms and, applying this risk assessment, systematically describe the CWD transmission risks experienced by CWD-positive farmed cervid operations in Minnesota and Wisconsin. A systematic review of literature related to CWD transmission informed our criteria to stratify CWD transmission risks to cervid operations into high-risk low uncertainty, moderate-risk high uncertainty, and negligible-risk low uncertainty categories. Case data from 34 CWD-positive farmed cervid operations in Minnesota and Wisconsin from 2002 to January 2019 were categorized by transmission risks exposure and evaluated for trends. The majority of case farms recorded high transmission risks (56%), which were likely sources of CWD, but many (44%) had only moderate or negligible transmission risks, including most of the herds (62%) detected since 2012. The presence of CWD-positive cervid farms with only moderate or low CWD transmission risks necessitates further investigation of these risks to inform effective control measures.

Modelling the effect of test-and-slaughter strategies to control bovine tuberculosis in endemic high prevalence herds.

Bovine tuberculosis (bTB) prevalence substantially increased over the past two decades with relatively high impact on large dairy herds, raising the concern of regulatory authorities and industry stakeholders, and threatening animal and public health. Lack of resources, together with the economic and social consequences of whole-herd stamping-out, makes depopulation an impractical disease control alternative in these herds. The increase in bTB prevalence was associated with demographic and management changes in the dairy industry in Uruguay, reducing the efficacy of the current control programme (i.e. status quo) based on intradermal serial testing with caudal fold- and comparative-cervical tuberculin test-and-slaughter of reactors (CFT-CCT). Here, we aimed to assess the epidemiological effectiveness of six alternative control scenarios based on test-and-slaughter of positive animals, using mathematical modelling to infer bTB-within-herd dynamics. We simulated six alternative control strategies consisting of testing adult cattle (>1 year) in the herd every 3 months using one test (in vivo or in vitro) or a combination in parallel of two tests (CFT, interferon-gamma release assay-IGRA- or enzyme-linked immunosorbent assay). Results showed no significant differences overall in the time needed to reach bTB eradication (median ranging between 61 and 82 months) or official bovine tuberculosis-free status (two consecutive negative herd tests) between any of the alternative strategies and the status quo (median ranging between 50 and 59 months). However, we demonstrate how alternative strategies can significantly reduce bTB prevalence when applied for restricted periods (6, 12 or 24 months), and in the case of IGRAc (IGRA using peptide-cocktail antigens), without incurring on higher unnecessary slaughter of animals (false positives) than the status quo in the first 6 months of the programme (p-value < .05). Enhanced understanding bTB-within-herd dynamics with the application of different control strategies help to identify optimal strategies to ultimately improve bTB control and bTB eradication from dairies in Uruguay and similar endemic settings.

Tracing Viral Transmission and Evolution of Bovine Leukemia Virus through Long Read Oxford Nanopore Sequencing of the Proviral Genome.

Bovine leukemia virus (BLV) causes Enzootic Bovine Leukosis (EBL), a persistent life-long disease resulting in immune dysfunction and shortened lifespan in infected cattle, severely impacting the profitability of the US dairy industry. Our group has found that 94% of dairy farms in the United States are infected with BLV with an average in-herd prevalence of 46%. This is partly due to the lack of clinical presentation during the early stages of primary infection and the elusive nature of BLV transmission. This study sought to validate a near-complete genomic sequencing approach for reliability and accuracy before determining its efficacy in characterizing the sequence identity of BLV proviral genomes collected from a pilot study made up of 14 animals from one commercial dairy herd. These BLV-infected animals were comprised of seven adult dam/daughter pairs that tested positive by ELISA and qPCR. The results demonstrate sequence identity or divergence of the BLV genome from the same samples tested in two independent laboratories, suggesting both vertical and horizontal transmission in this dairy herd. This study supports the use of Oxford Nanopore sequencing for the identification of viral SNPs that can be used for retrospective genetic contact tracing of BLV transmission.

Primary transcriptomes of Mycobacterium avium subsp. paratuberculosis reveal proprietary pathways in tissue and macrophages.

BACKGROUND: Mycobacterium avium subsp. paratuberculosis (MAP) persistently infects intestines and mesenteric lymph nodes leading to a prolonged subclinical disease. The MAP genome sequence was published in 2005, yet its transcriptional organization in natural infection is unknown. While prior research analyzed regulated gene sets utilizing defined, in vitro stress related or advanced surgical methods with various animal species, we investigated the intracellular lifestyle of MAP in the intestines and lymph nodes to understand the MAP pathways that function to govern this persistence. RESULTS: Our transcriptional analysis shows that 21%, 8% and 3% of the entire MAP genome was represented either inside tissues, macrophages or both, respectively. Transcripts belonging to latency and cell envelope biogenesis were upregulated in the intestinal tissues whereas those belonging to intracellular trafficking and secretion were upregulated inside the macrophages. Transcriptomes of natural infection and in vitro macrophage infection shared genes involved in transcription and inorganic ion transport and metabolism. MAP specific genes within large sequence polymorphisms of ancestral M. avium complex were downregulated exclusively in natural infection. CONCLUSIONS: We have unveiled common and unique MAP pathways associated with persistence, cell wall biogenesis and virulence in naturally infected cow intestines, lymph nodes and in vitro infected macrophages. This dichotomy also suggests that in vitro macrophage models may be insufficient in providing accurate information on the events that transpire during natural infection. This is the first report to examine the primary transcriptome of MAP at the local infection site (i.e. intestinal tissue). Regulatory pathways that govern the lifecycle of MAP appear to be specified by tissue and cell type. While tissues show a "shut-down" of major MAP metabolic genes, infected macrophages upregulate several MAP specific genes along with a putative pathogenicity island responsible for iron acquisition. Many of these regulatory pathways rely on the advanced interplay of host and pathogen and in order to decipher their message, an interactome must be established using a systems biology approach. Identified MAP pathways place current research into direct alignment in meeting the future challenge of creating a MAP-host interactome.

Experimental validation of a nested polymerase chain reaction targeting the genetic element ISMAP02 for detection of Mycobacterium avium subspecies paratuberculosis in bovine colostrum.

Colostrum samples experimentally inoculated with Mycobacterium avium subsp. paratuberculosis (MAP; strain K-10) at increasing concentrations between 1 x 10(1) and 1 x 10(9) cells/ml were tested for recovery of MAP DNA using a nested ISMAP02 target polymerase chain reaction initially developed for detecting MAP DNA in fecal samples. The following detection rates were achieved for sample replicates inoculated with unsonicated MAP pure stock: 100% between 1 x 10(7) and 1 x 10(9) cells/ml, 75% between 1 x 10(3) and 1 x 10(6) cells/ml, and 50% between 1 x 10(1)and 1 x 10(2) cells/ml replicates. Detection rates achieved for the colostrum sample replicates inoculated with sonicated MAP cell suspension were 75% for 1 x 10(9) cells/ml, 100% between 1 x 10(7) and 1 x 10(8) cells/ml, 75% for 1 x 10(6) cells/ml, 0 for 1 x 10(4) cells/ml, and 25% between 1 x 10(1) and 1 x 10(3) cells/ml. When negative control colostrum samples were tested, 16 of 18 (89%) samples were correctly detected as negative for MAP DNA using the current assay. In conclusion, the MAP DNA detection rates of the present assay improved with increasing concentrations of MAP in the colostrum sample replicates, although MAP DNA was also detected in 2 of 18 (11%) negative control samples, suggesting an undefined technical problem with the assay or, perhaps, sample contamination during preparation. Overall, the present findings suggest a potential role of the proposed polymerase chain reaction assay to detect MAP in colostrum. However, adoption of this test for use in routine screening of field colostrum for MAP awaits findings from an ongoing field validation study.

Effect of a plasma-derived colostrum replacement feeding program on adult performance and longevity in Holstein cows.

OBJECTIVE: To evaluate longevity, milk production, and breeding performance in adult Holstein cows fed either a plasma-derived commercial colostrum replacer (CR) or raw bovine maternal colostrum (MC) at birth. DESIGN: Randomized controlled clinical trial. ANIMALS: 497 heifer calves born in 12 commercial dairies located in Minnesota and Wisconsin. PROCEDURES: All calves were separated from their dams within 30 to 60 minutes after birth and systematically assigned to be fed either MC (control group [n = 261 calves]) or CR (treatment group [236]). Calves were observed from birth up to adulthood (approx 54 months old), during which time death and culling events plus milk yield and breeding performance data were collected. Time to death, time to culling, time to death or culling combined, time to first calving, and time to conception intervals were evaluated by use of proportional hazards survival analysis models. Number of times inseminated per conception and lifetime milk yield (up to 54 months old) were evaluated by use of general linear models. RESULTS: Cows fed CR as calves at the time of birth were no different than cows fed MC as calves with respect to overall risk of death, culling, or death or culling combined (from birth to 54 months of follow-up and from first calving to 54 months old); lifetime milk yield; and breeding performance. CONCLUSIONS AND CLINICAL RELEVANCE: No difference was detected in overall risk of death or culling, milk production, or reproductive performance between cows fed CR and those fed MC as calves at birth.

Implications of farmed-cervid movements on the transmission of chronic wasting disease.

Chronic wasting disease is a transmissible spongiform encephalopathy that affects cervids with a clinical picture of muscle wasting in infected animals. The objective of this study was to quantify movement patterns of farmed cervids in the state of Minnesota as a model for identifying potential disease mitigation points. Time aggregated network analysis was performed on data consisting of 1221 intra-state cervid movements from farms located within Minnesota (n = 432 farms). Intra-state movements accounted for 48.2 % of all documented movements (2578) in Minnesota from 2013 to 2018; the remaining movements were inter-state. Annual networks were sparse in nature with low graph densities (6.9 × 10-4 - 1.4 × 10-3) and transitivity (0.06-0.12). Frequency of movements increased significantly (p < 0.05) in the months of September and October before decreasing in November, which coincided with the breeding and hunting seasons. Some of these contacts were as far as 500 km apart. The median length of infection chains for CWD positive farms was estimated to be 5.0 and 6.0 farms in-and out-going infection chains, respectively. A k-test analysis demonstrated that the observed median number of infected farms directly connected to other infected farms was 2.0, which was significantly higher than a fortuitous event (p = 0.002). Movements of cervids between farms were largely unpredictable with very low edge overlap (mean 0.02 %) from year to year, suggesting that persistent commercial relationships among farms were rare. In conclusion, long distance trade movements present a risk for spread of chronic wasting disease in Minnesota. The sparse networks and unpredictable farm contacts could be because cervid production is not as vertically integrated as other species-differentiated and established industries, such as swine or poultry. Our analytical approach can be used to understand chronic wasting disease in other states in the U.S. and North America in general.

Lessons Learned From the Stakeholder Engagement in Research: Application of Spatial Analytical Tools in One Health Problems.

Stakeholder engagement in research is widely advocated as a tool to integrate diverse knowledge and perspectives in the management of health threats while addressing potential conflicts of interest. Although guidelines for stakeholder engagement exist in public health and environmental sciences, the feasibility of actionable decisions based on scientific analyses and the lessons learned from the stakeholder engagement in the process co-creation of knowledge have been rarely discussed in One Health literature and veterinary sciences. Risk maps and risk regionalization using spatiotemporal epidemiological/analytical tools are known to improve risk perception and communication. Risk maps are useful when informing policy and management decisions on quarantine, vaccination, and surveillance intended to prevent or control threats to human, animal, or environmental health interface (i.e., One Health). We hypothesized that researcher-stakeholder engagement throughout the research process could enhance the utility of risk maps; while identifying opportunities to improve data collection, analysis, interpretation, and, ultimately, implementation of scientific/evidence-based management and policy measures. Three case studies were conducted to test this process of co-creation of scientific knowledge, using spatiotemporal epidemiological approaches, all related to One Health problems affecting Minnesota. Our interpretation of the opportunities, challenges, and lessons learned from the process are summarized from both researcher and stakeholder perspectives. By sharing our experience we intend to provide an understanding of the expectations, realizations, and "good practices" we learned through this slow-moving iterative process of co-creation of knowledge. We hope this contribution benefits the planning of future transdisciplinary research related to risk map-based management of One Health problems.

Efficacy of feeding plasma-derived commercial colostrum replacer for the prevention of transmission of Mycobacterium avium subsp paratuberculosis in Holstein calves.

OBJECTIVE: To estimate the relative risk of paratuberculosis (Johne's disease [JD]) in calves fed a plasma-derived colostrum-replacement (CR) product versus raw bovine maternal colostrum (MC). STUDY DESIGN: Randomized controlled clinical trial. ANIMALS: 497 heifer calves born in 12 JD-endemic commercial Holstein dairy farms located in Minnesota and Wisconsin. PROCEDURES: Every calf was separated from its dam within 30 to 60 minutes after birth and systematically assigned to be fed raw bovine MC (control group, n = 261 calves) or CR (treatment group, 236 calves). The calves were monitored to adulthood and tested for Mycobacterium avium subsp paratuberculosis (MAP) infection by use of an ELISA to detect serum antibodies against MAP and bacterial culture for MAP in feces at approximately 30, 42, and 54 months of age. Weibull regression models were used to evaluate the effect of feeding CR (vs raw bovine MC) on the risk of developing JD infection. RESULTS: Calves fed CR at birth were less likely (hazard ratio = 0.559) to become infected with MAP (as determined by use of an ELISA, bacterial culture, or both diagnostic tests), compared with the likelihood for calves fed MC at birth. CONCLUSIONS AND CLINICAL RELEVANCE: This study revealed that feeding CR reduced the risk of developing MAP infection in Holstein calves born in JD-endemic herds, which implied that feeding raw bovine MC may be a source of MAP for calves. Plasma colostrum-replacement products may be an effective management tool for use in dairy herds attempting to reduce the prevalence of JD.

Simulation model for evaluation of testing strategies for detection of paratuberculosis in midwestern US dairy herds.

We developed a stochastic simulation model to compare the herd sensitivity (HSe) of five testing strategies for detection of Mycobacterium avium subsp. paratuberculosis (Map) in Midwestern US dairies. Testing strategies were ELISA serologic testing by two commercial assays (EA and EB), ELISA testing with follow-up of positive samples with individual fecal culture (EAIFC and EBIFC), individual fecal culture (IFC), pooled fecal culture (PFC), and culture of fecal slurry samples from the environment (ENV). We assumed that these dairies had no prior paratuberculosis-related testing and culling. We used cost-effectiveness (CE) analysis to compare the cost to HSe of testing strategies for different within-herd prevalences. HSe was strongly associated with within-herd prevalence, number of Map organisms shed in feces by infected cows, and number of samples tested. Among evaluated testing methods with 100% herd specificity (HSp), ENV was the most cost-effective method for herds with a low (5%), moderate (16%) or high (35%) Map prevalence. The PFC, IFC, EAIFC and EBIFC were increasingly more costly detection methods. Culture of six environmental samples per herd yielded >or=99% HSe in herds with >or=16% within-herd prevalence, but was not sufficient to achieve 95% HSe in low-prevalence herds (5%). Testing all cows using EAIFC or EBIFC, as is commonly done in paratuberculosis-screening programs, was less likely to achieve a HSe of 95% in low than in high prevalence herds. ELISA alone was a sensitive and low-cost testing method; however, without confirmatory fecal culture, testing 30 cows in non-infected herds yielded HSp of 21% and 91% for EA and EB, respectively.

Evaluation of progress made by dairy and beef herds enrolled in the Minnesota Johne's Disease Control Program.

OBJECTIVE: To evaluate progress made by cattle herds in the control of paratuberculosis (Johne's disease) through participation in the Minnesota Johne's Disease Control Program (MNJDCP). DESIGN: Retrospective records analysis. SAMPLE POPULATION: Data for dairy and beef herds participating in the MNJDCP. PROCEDURES: Data for the MNJDCP were collected for analyses. Outcome measures included changes in numbers of participating cattle producers, risk assessment scores, and within-herd seroprevalence of Johne's disease by year of program participation. RESULTS: Results revealed steady increases in program participation by cattle producers in Minnesota over time, with > 30% of dairy producers and 2% of beef producers in the state participating by the end of 2006. Despite risk of introduction of Johne's disease to cattle herds through continued introduction of cattle from other herds, dairy and beef herds in the Management Program of the MNJDCP reduced their on-farm risk assessment scores during the program. Dairy herds in the Management Program reduced their mean within-herd seroprevalence 1.1% during the first year, 2.6% during the first 2 years, and 4.0% during the first 3 years of program participation. Significant within-herd seroprevalence reduction was also detected for beef herds that participated in the Management Program for at least 3 years. CONCLUSIONS AND CLINICAL RELEVANCE: This study revealed a reduction in the risk of withinherd transmission of Johne's disease and seroprevalence over time in dairy and beef herds in the Management Program of the MNJDCP. This is consistent with a positive effect of the program for the control of Johne's disease in cattle.