A Systematic Review of Telehealth-Based Pediatric Cancer Rehabilitation Interventions on Disability

Background: Telehealth is an emerging method which may overcome barriers to rehabilitation access for pediatric cancer survivors (aged ≤19 years). This systematic review aimed to examine telehealth-based rehabilitation interventions aimed at preventing, maintaining, or improving disability in pediatric cancer survivors. Methods: We performed systematic searches in Ovid MEDLINE, Ovid EMBASE, Cochrane Library, SCOPUS, Web of Science, and CINAHL Plus between 1994 and 2022. Eligible studies included telehealth-based interventions assessing disability outcomes in pediatric cancers. Results: Database searches identified 4,040 records. Nine unique interventions met the eligibility criteria. Telehealth delivery methods included telephone (n = 6), email (n = 3), mobile health applications (n = 3), social media (n = 3), videoconferencing (n = 2), text messaging (n = 2), active video gaming (n = 2), and websites (n = 2). Interventions focused on physical activity (n = 8) or self-management (n = 1). Outcomes assessing disability varied (n = 6). Three studies reported statistically and clinically significant results. Narrative synthesis of findings was constructed based on the Picker's principles for patient-centered care: (1) values, preferences, and needs; (2) involve family and friends; (3) coordination of care; (4) provide social support; (5) holistic well-being; and (6) information and communication. Conclusions: Telehealth-based rehabilitation interventions for pediatric cancer survivors is an emerging research area with potential to improve disability outcomes. Adequately powered trials with consistency in disability outcome measures are warranted. Additional research is needed to determine the effectiveness and best practices for telehealth-based pediatric cancer rehabilitation.

Assessing the Suitability of a Virtual 'Pink Warrior' for Older Breast Cancer Survivors during COVID-19: A Pilot Study

The COVID-19 pandemic impacted the conduct of in-person physical activity (PA) interventions among older survivors of BC, who need such interventions to stay active and prevent functional decline. We tested the feasibility of virtually delivering an exergame-based PA intervention to older BC survivors. We enrolled 20 female BC survivors ≥55 years and randomly assigned them to two groups. The intervention group (Pink Warrior 2) received 12 weekly virtual exergame sessions with behavioral coaching, survivorship navigation support, and a Fitbit for self-monitoring. The control group received 12 weekly phone-based survivorship discussion sessions and wore a Mi Band 3. Feasibility was evaluated by rates of recruitment (≥0.92 participants/center/month), retention (≥80%), and group attendance (≥10 sessions), percentage of completed virtual assessments, and number of technology-related issues and adverse events. Intervention acceptability was measured by participants' ratings on a scale of 1 (strongly disagree) to 5 (strongly agree). The recruitment rate was 1.93. The retention and attendance rates were 90% and 88% (≥10 sessions), respectively. Ninety-six percent completed virtual assessments without an adverse event. Acceptability was high (≥4). The intervention met benchmarks for feasibility. Additional research is needed to further understand the impact of virtually delivered PA interventions on older BC survivors.

System-level barriers and facilitators to cancer rehabilitation delivery for children with cancer

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Background: Up to 20% of childhood cancer survivors suffer from a significant physical function impairment due to cancer or cancer treatment. Early intervention with Occupational Therapy (OT) and Physical Therapy (PT) increases engagement in personal care, leisure interests, school-based tasks, return to work, and prevents cognitive decline. Despite this, less than 30% of childhood cancer survivors receive PT services. To date, facilitators and barriers to implementing cancer rehabilitation (CR) for pediatric cancer survivors have not been adequately explored. Thus, the aim of this research was to identify system-level barriers and facilitators to CR delivery based on surveys completed by hospital administrators, oncology physicians, advanced practice providers, and OT/PT therapists. Methods: A cross-sectional method was employed. Three previously published cardiac rehabilitation delivery instruments specific for administrators, OT/PT therapists and clinical providers respectively were adapted to evaluate CR delivery. All surveys used a 5-point Likert-type response format (e.g., 1 = strongly disagree to 5 = strongly agree). Surveys ranged from 12 items (therapist survey) to 23 items (administrator survey). Questions pertained to knowledge, attitudes, and perceptions regarding CR. Results: A total of 20 administrators (mean age, 49.95 years old, 65% non-Hispanic White, 65% female), 20 providers (mean age, 43.4 years old, 71.4% non-Hispanic White, 67% female), and 20 therapists (mean age, 38.3 years old, 70% non-Hispanic white, 84% female) completed surveys. Administrators’ results indicated mid-range CR knowledge (median: 3.5; IQR 2,5), and all perceived CR as important or extremely important to outpatient care (median: 5; IQR 4,5). Limited insurance coverage and lack of space were the top barriers identified by administrators. Eighty percent of providers endorsed that clinical practice guidelines promote CR referral (median 4; IQR 4,5) and none reported being skeptical of CR benefits. Provider-identified barriers included an inconvenient referral process, lack of CR patient-education materials, and inadequate information on external CR resources. Therapists identified rate of absenteeism and referral rates as barriers to CR. Ninety percent of therapists reported hybrid CR delivery (supervised and unsupervised exercise) could facilitate CR participation (median 4; IQR 4,4). Conclusions: System-wide, there was adequate knowledge and positive perceptions and attitudes regarding CR. However, we identified multiple barriers presenting opportunities for multilevel interventions. These included: insurance coverage advocacy, streamlining referral processes to CR services, providing information on external CR programs, providing patient education materials, and leveraging hybrid CR delivery to optimize participation.

Feasibility and Acceptability of an Active Video Game-Based Physical Activity Support Group (Pink Warrior) for Survivors of Breast Cancer: Randomized Controlled Pilot Trial

BACKGROUND

Survivors of breast cancer with functional limitations have a 40% higher mortality rate than those without. Despite the known benefits of physical activity (PA), <40% of survivors of breast cancer meet the recommendations for PA. The combination of active video games (AVGs) and group-based PA counseling may hold potential for motivating PA adoption and improving physical function. However, this method has not been widely studied in survivors of breast cancer.

OBJECTIVE

We aimed to determine the feasibility and acceptability of a group AVG-based multicomponent PA intervention and estimate its effect size and variability on PA and physical function in female survivors of breast cancer in a clinic setting.

METHODS

Female survivors of breast cancer (N=60) were recruited through the clinic and randomly assigned to the intervention group (12 weekly sessions) or the control group (existing support group). The intervention group received game-based pedometers and participated in weekly group AVG sessions, PA behavioral coaching, and survivorship navigation discussions. A participant manual with weekly reflection worksheets was provided to reinforce the coaching lessons and promote self-led PA. The control group received conventional pedometers and participated in an existing breast cancer support group. Feasibility was assessed by enrollment rate (≥50%), retention rate (≥80%), group attendance rate (75% attending ≥9 sessions [intervention group]), and the number of technological issues and adverse events. Acceptability was measured by participants' attitudes (from strongly disagree=1 to strongly agree=5) toward the use of AVGs and the overall program. The outcomes included PA (accelerometers) and physical function (Short Physical Performance Battery and gait speed). Analysis of covariance was used to determine differences in PA and physical function between the groups. The Cohen d and its 95% CI determined the effect size and variability, respectively. All the analyses followed the intention-to-treat principle.

RESULTS

Participants were an average of 57.4 (SD 10.5) years old, 70% (42/60) White, and 58% (35/60) off treatment. The enrollment rate was 55.9% (66/118). Despite substantial long-term hurricane-related disruptions, we achieved an 80% (48/60) retention. The intervention group's attendance rate was 78% (14/18), whereas the control group's attendance rate was 53% (9/17). Of the 26 game-based pedometers, 3 (12%) were damaged or lost. No study-related adverse events occurred. Acceptability items were highly rated. Steps (β=1621.64; P=.01; d=0.72), Short Physical Performance Battery (β=.47; P=.01; d=0.25), and gait speed (β=.12; P=.004; d=0.48) had a significant intervention effect.

CONCLUSIONS

The intervention was feasible and acceptable in this population despite the occurrence of a natural disaster. Pilot results indicate that group AVG sessions, PA coaching, and survivorship navigation produced moderate effects on PA and physical functioning. AVGs with PA counseling can potentially be used in existing breast cancer support groups to encourage PA and improve physical function.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02750241; https://clinicaltrials.gov/ct2/show/NCT02750241.

Genome-wide association analysis for susceptibility to infection by Mycobacterium avium ssp. paratuberculosis in US Holsteins

Paratuberculosis, or Johne's disease, is a chronic, granulomatous, gastrointestinal tract disease of cattle and other ruminants caused by the bacterium Mycobacterium avium subspecies paratuberculosis (MAP). Control of Johne's disease is based on programs of testing and culling animals positive for infection with MAP and concurrently modifying management to reduce the likelihood of infection. The current study was motivated by the hypothesis that genetic variation in host susceptibility to MAP infection can be dissected and quantifiable associations with genetic markers identified. Two separate GWAS analyses were conducted, the first using 897 genotyped Holstein artificial insemination sires with phenotypes derived from incidence of MAP infection among daughters based on milk ELISA testing records. The second GWAS analysis was a case-control design using US Holstein cows phenotyped for MAP infection by serum ELISA or fecal culture tests. Cases included cows positive for either serum ELISA, fecal culture, or both. Controls consisted of animals negative for all tests conducted. A total of 376 samples (70 cases and 306 controls) from a University of Minnesota Johne's management demonstration project and 184 samples (76 cases and 108 controls) from a Michigan State University study were used. Medium-density (sires) and high-density (cows) genotype data were imputed to full genome sequence for the analyses. Marker-trait associations were analyzed using the single-step (ss)GWAS procedure implemented in the BLUPF90 suite of programs. Evidence of significant genomic contributions for susceptibility to MAP infection were observed on multiple chromosomes. Results were combined across studies in a meta-analysis, and increased support for genomic regions on BTA7 and BTA21 were observed. Gene set enrichment analysis suggested pathways for antigen processing and presentation, antimicrobial peptides and natural killer cell-mediated cytotoxicity are relevant to variation in host susceptibility to MAP infection, among others. Genomic prediction was evaluated using a 5-fold cross-validation, and moderate correlations were observed between genomic breeding value predictions and daughter averages (∼0.43 to 0.53) for MAP infection in testing data sets. These results suggest that genomic selection against susceptibility to MAP infection is feasible in Holstein cattle.

Development of an Enhanced Recovery Program in Pediatric, Adolescent, and Young Adult Surgical Oncology Patients

Enhanced recovery after surgery (ERAS) protocols are standardized perioperative treatment plans aimed at improving recovery time in patients following surgery using a multidisciplinary team approach. These protocols have been shown to optimize pain control, improve mobility, and decrease postoperative ileus and other surgical complications, thereby leading to a reduction in length of stay and readmission rates. To date, no ERAS-based protocols have been developed specifically for pediatric patients undergoing oncologic surgery. Our objective is to describe the development of a novel protocol for pediatric, adolescent, and young adult surgical oncology patients. Our protocol includes the following components: preoperative counseling, optimization of nutrition status, minimization of opioids, meticulous titration of fluids, and early mobilization. We describe the planning and implementation challenges and the successes of our protocol. The effectiveness of our program in improving perioperative outcomes in this surgical population could lead to the adaptation of such protocols for similar populations at other centers and would lend support to the use of ERAS in the pediatric population overall.

Satisfaction with and recommendations to improve telehealth visits among adolescents and young adults with cancer during the COVID-19 pandemic

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Background: The COVID-19 pandemic has negatively impacted morbidity, mortality, and economic status globally. Adolescents and young adults (AYAs, age 15-39) with cancer may experience disparities in access to health care, compounded by social distancing and stay-at-home orders aimed at reducing the spread of COVID-19. The use of telehealth platforms for clinical visits has accelerated rapidly due to policy changes during the pandemic. Telehealth may provide an avenue for accessing healthcare services among AYAs with cancer; yet, there are few data on AYAs’ preferences and satisfaction relating to telehealth. Our study examined telehealth utilization, satisfaction, preferences and future recommendations among AYAs with a cancer diagnosis. Methods: AYAs in active cancer treatment or in post-treatment survivorship completed an online questionnaire that assessed their experience with telehealth, including: satisfaction with the telehealth visit, likelihood of participating in a future telehealth visit, topics participants would like to discuss via telehealth, and open-ended comments regarding suggestions for improving future telehealth visits. Participants were recruited in two cohorts: a pre-vaccine cohort (September 2020 - January 2021) prior to availability of COVID-19 vaccines in Texas; and, a post-vaccine cohort (April 2021 - May 2021) after vaccine availability. Descriptive statistics were used to summarize preliminary findings. Results: Participants included 273 AYAs with cancer (mean age, 33.8 years old, 26% male, 73% non-Hispanic White, 11% in active treatment, 53% in post-vaccine cohort). Of 71.7% who participated in at least one telehealth visit, 50.9% were somewhat or very satisfied with their visit(s). Topics that all participants preferred to address via telehealth included: stress management (34%); sleep quality (31.7%); diet/nutrition (32.1%); and mental health (29.5%).Topics least preferred for telehealth included fertility counseling (16.7%) and sexual health (13.7%). Open-ended comments from participants highlighted the importance of healthcare providers taking time to listen to their concerns during their visits. Participants suggested that telehealth encounters can be improved by ensuring adequate time for the visit plus good video and audio quality, and using telehealth for follow-up visits rather than initial consultations. Conclusions: About half of AYAs who had participated in a telehealth visit indicated satisfaction with the visit(s). Findings indicated AYAs’ preferences for the types of topics that are most and least preferred to address in telehealth visits, as well as specific recommendations for improving the quality of visits. Consideration of AYAs’ preferences and recommendations in the ongoing implementation of telehealth may help improve patient satisfaction.

Non-pharmacological sleep interventions for pediatric cancer patients and survivors: a systematic review protocol

BACKGROUND

Sleep disturbances constitute a common complication in pediatric cancer patients and survivors and are frequently severe enough to warrant treatment. Suboptimal sleep has been associated with decreased emotional well-being and cognitive functioning and increased behavioral problems. Standardized guidelines for non-pharmacological sleep interventions for adults with cancer exist, but no standard of care intervention or standard guidelines are available to guide such intervention in pediatric cancer patients and survivors. Therefore, effective behavioral interventions for improving sleep quality need to be identified. The objective of the review is to evaluate the effect of non-pharmacological sleep interventions on sleep quality in pediatric cancer patients and survivors.

METHODS

The review will consider studies that include children and adolescents between 0 and 18 years diagnosed with cancer or who have a history of cancer who have non-respiratory sleep disturbance. We will include experimental and quasi-experimental studies evaluating non-pharmacological interventions such as psychological interventions, technical/device interventions, interventions targeting physical activity, and complementary and alternative medicine interventions (e.g., yoga, massage, music). Interventions involving medications, ingestible supplements, products purported to work through absorption, and medical devices will be excluded. Primary outcome will be sleep quality as measured by methods including retrospective ratings, daily sleep diary, and validated questionnaires. Secondary outcomes will include total sleep time, sleep onset latency, wake after sleep onset, daytime sleepiness, and daytime sleep duration (naps) as measured by retrospective ratings, daily sleep diary, validated questionnaires, and/or actigraphy. Databases will include MEDLINE (Ovid), EMBASE (Ovid), Cochrane Library, CINAHL (Ebsco), and PsycINFO (Ovid) and will be queried from database inception to present. Two reviewers will independently screen all citations, full-text articles, and extract data. The study methodological quality will be assessed using Joanna Briggs Institute (JBI) critical appraisal tools. Data will be extracted and findings pooled and synthesized using a meta-aggregation approach via the JBI System for the Unified Management, Assessment, and Review of Information (SUMARI). If feasible, we will conduct random effects meta-analysis. Additional analyses will be conducted to explore the potential sources of heterogeneity (e.g., methodological quality, study design, outcome measures).

DISCUSSION

This systematic review will synthesize and consolidate evidence on existing non-pharmacological interventions to improve sleep in pediatric cancer patients and survivors. Findings may help inform practitioners working with pediatric cancer patients and survivors experiencing sleep disturbances and is intended to identify gaps and opportunities to improve methodical quality of further non-pharmacological sleep intervention research in this population toward developing an eventual standard of care.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020200397 .

Use of active video games with or without videoconferencing on health outcomes in adolescent and young adult cancer survivors: a systematic review

PURPOSE

Adolescent and young adult (AYA) cancer survivors experience greater functional deficits compared to non-cancer peers or older survivors with a similar diagnosis. Physical activity (PA) is a key strategy for mitigating functional decline, and motivation and peer support are critical PA facilitators in AYA cancer survivors. Active video games (AVGs) may be a "gateway" method to promote PA. Further, integrating AVGs into group videoconferencing, a medium used by AYAs to socialize, can capitalize on peer support needed for PA motivation. Thus, we examined the use of AVGs and/or videoconferencing in PA interventions that included AYA survivors and the effect on physical function and health outcomes.

METHODS

Seven electronic databases were searched from incept to January 2020. Search terms included videoconferencing, video games, exercise, and cancer. The protocol is registered on PROSPERO: CRD42020163491. Two reviewers evaluated eligibility and methodological quality using Cochrane's risk of bias tools.

RESULTS

Six unique studies were included with 97% reviewer agreement. All used AVGs, none used videoconferencing alone, and one used both. Study designs and outcome measures were heterogeneous. Only one study solely targeted AYA survivors. Most were low to medium quality. Few showed significant improvements in quality of life (QOL) and fatigue (n=3), coordination/balance (n=2), and aerobic capacity (n=1).

CONCLUSIONS

PA interventions using AVGs and/or videoconferencing may improve QOL and fatigue, but evidence on function is lacking. Rigorous interventions targeting AYA survivors are needed.

IMPLICATIONS FOR CANCER SURVIVORS

Using AVGs and/or videoconferencing to facilitate PA may improve QOL and fatigue.

Pre-COVID-19 food insecurity prevalence and risk factors in caregivers of pediatric cancer patients at a children’s cancer hospital

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Background: Food insecurity (FI) affects 1 in 5 US households with children and is associated with malnutrition and poor diet quality in children. Malnutrition negatively impacts clinical trial outcomes, chemotherapy tolerance, and survival rate in cancer patients, who may be at higher FI risk given the financial toxicity of treatment. Thus, we aimed to assess FI prevalence and sociodemographics of pediatric patient caregivers at MD Anderson Cancer Center Children’s Cancer Hospital (MDACC-CCH) and to identify healthcare provider sociodemographics and FI practice considerations. Methods: We surveyed caregivers and providers at MDACC-CCH anonymously from December 2019 to January 2020. Caregiver surveys included sociodemographics and The Hunger Vital Sign FI screening tool. Oncologists and other providers were surveyed on FI-related practice considerations. Univariate relationships between known covariates and FI were explored using purposeful covariate selection and multivariable logistic regression to model variables associated with FI risk factors. Results: Baseline characteristics are listed in Table. Of 67 caregiver responses, 36% were positive for FI. Univariate analyses revealed that race, education level, spousal/child support, marital status, and household income were associated with FI status. Final logistic regression model indicated that race other than Non-Hispanic White and lower education level were positively associated with FI. Of 38 provider responses, 58% reported being knowledgeable about FI to some extent. No providers referred patients to community food access resources. Conclusions: In a small pilot study, FI is prevalent in families of pediatric cancer patients at MDACC-CCH and may be associated with race and education level. Further research is needed to assess the impact of the COVID-19 pandemic on FI in this population and to determine appropriate interventions and clinical pathways to improve FI status. [Table: see text]

Use of a voluntary testing program to study the spatial epidemiology of Johne's disease affecting dairy herds in Minnesota: a cross sectional study

Background

One of the key steps in the management of chronic diseases in animals including Johne’s disease (JD), caused by Mycobacterium avium subsp. paratuberculosis (MAP), is the ability to track disease incidence over space and time. JD surveillance in the U.S. dairy cattle is challenging due to lack of regulatory requirements, imperfect diagnostic tests, and associated expenses, including time and labor. An alternative approach is to use voluntary testing programs. Here, data from a voluntary JD testing program, conducted by the Minnesota Dairy Herd Improvement Association, were used to: a) explore whether such a program provides representative information on JD-prevalence in Minnesota dairy herds, b) estimate JD distribution, and, c) identify herd and environmental factors associated with finding JD-positive cows. Milk samples (n = 70,809) collected from 54,652 unique cows from 600 Minnesota dairy herds between November 2014 and April 2017 were tested using a MAP antibody ELISA. Participant representativeness was assessed by comparing the number of JD-tested herds with the number of herds required to estimate the true disease prevalence per county based on official statistics from the National Agricultural Statistical Services. Multivariable logistic regression models, with and without spatial dependence between observations, were then used to investigate the association between herd status to JD (positive/negative), as indicated by milk ELISA results, and available covariates at the herd level.

Results

Within the study population, at least one test-positive cow was found in 414 of 600 (69%) herds. Results indicated that large herds that test frequently and herds located in loamy or silt soils are more likely to have at least one MAP test-positive cow. After adjusting for herd size, testing frequency, and soil type, there was no spatial dependence in JD risk between neighboring dairies within 5 to 20 km. Furthermore, the importance of collecting data on herd management, feed, and biosecurity for insightful interpretations was recognized. The study suggested that, although limited, the voluntary testing database may support monitoring JD status.

Conclusions

Results presented here help elucidate the spatial characteristics of JD in Minnesota and the study may ultimately contribute to the design and implementation of surveillance programs for the disease.

Knowledge gaps that hamper prevention and control of Mycobacterium avium subspecies paratuberculosis infection

In the last decades, many regional and country-wide control programmes for Johne's disease (JD) were developed due to associated economic losses, or because of a possible association with Crohn's disease. These control programmes were often not successful, partly because management protocols were not followed, including the introduction of infected replacement cattle, because tests to identify infected animals were unreliable, and uptake by farmers was not high enough because of a perceived low return on investment. In the absence of a cure or effective commercial vaccines, control of JD is currently primarily based on herd management strategies to avoid infection of cattle and restrict within-farm and farm-to-farm transmission. Although JD control programmes have been implemented in most developed countries, lessons learned from JD prevention and control programmes are underreported. Also, JD control programmes are typically evaluated in a limited number of herds and the duration of the study is less than 5 year, making it difficult to adequately assess the efficacy of control programmes. In this manuscript, we identify the most important gaps in knowledge hampering JD prevention and control programmes, including vaccination and diagnostics. Secondly, we discuss directions that research should take to address those knowledge gaps.

Epidemiologic Investigation of Highly Pathogenic H5N2 Avian Influenza Among Upper Midwest U.S. Turkey Farms, 2015

In 2015, an outbreak of H5N2 highly pathogenic avian influenza (HPAI) occurred in the United States, severely impacting the turkey industry in the upper midwestern United States. Industry, government, and academic partners worked together to conduct a case-control investigation of the outbreak on turkey farms in the Upper Midwest. Case farms were confirmed to have HPAI-infected flocks, and control farms were farms with noninfected turkey flocks at a similar stage of production. Both case and control farms were affiliated with a large integrated turkey company. A questionnaire administered to farm managers and supervisors assessed farm biosecurity, litter handling, dead bird disposal, farm visitor and worker practices, and presence of wild birds on operations during the 2 wk prior to HPAI confirmation on case premises and the corresponding time frame for control premises. Sixty-three farms, including 37 case farms and 26 control farms were included in the analysis. We identified several factors significantly associated with the odds of H5N2 case farm status and that may have contributed to H5N2 transmission to and from operations. Factors associated with increased risk included close proximity to other turkey operations, soil disruption (e.g., tilling) in a nearby field within 14 days prior to the outbreak, and rendering of dead birds. Observation of wild mammals near turkey barns was associated with reduced risk. When analyses focused on farms identified with H5N2 infection before April 22 (Period 1), associations with H5N2-positive farm status included soil disruption in a nearby field within 14 days prior to the outbreak and a high level of visitor biosecurity. High level of worker biosecurity had a protective effect. During the study period after April 22 (Period 2), factors associated with HPAI-positive farm status included nonasphalt roads leading to the farm and use of a vehicle wash station or spray area. Presence of wild birds near dead bird disposal areas was associated with reduced risk. Study results indicated that the initial introduction and spread of H5N2 virus likely occurred by both environmental and between-farm pathways. Transmission dynamics appeared to change with progression of the outbreak. Despite enhanced biosecurity protocols, H5N2 transmission continued, highlighting the need to review geographic/topologic factors such as farm proximity and potential dust or air transmission associated with soil disruption. It is likely that biosecurity improvements will reduce the extent and speed of spread of future outbreaks, but our results suggest that environmental factors may also play a significant role in farms becoming infected with HPAI.

Epidemic simulation of a foot and mouth disease outbreak in Minnesota

Foot and mouth disease (FMD) is a primary transboundary livestock disease of international concern. Outbreaks of the disease have recently occurred in several countries that were previously FMD-free. For countries with limited direct experience of this disease, modelling is a useful tool for the study of a potential outbreak. The objectives of this study were to determine specific FMD risk parameters for Minnesota and the United States (USA) and to use these parameters to create a baseline FMD outbreak model for Minnesota. Of specific interest was to assess whether the type of herd in which the outbreak began (a dairy herd or a large-scale swine herd) influenced the basic model outcomes of outbreak size and duration, and to examine the effects of depopulation and movement controls. The mean values for disease duration, outbreak duration and number of farms and animals infected were larger in the scenario with a dairy index herd. The results of these two outbreak models demonstrated the entire spectrum of FMD outbreak types; that is, from limited, focal outbreaks to widespread, uncontrolled outbreaks. The findings from this study provide details of a baseline model that emergency preparedness planners can use to evaluate response strategies for a potential incursion of FMD into the USA. These findings are also of value for all countries as veterinary authorities develop or adjust their FMD emergency response plans.

Emergency vaccination use in a modelled foot and mouth disease outbreak in Minnesota

Epidemiological modelling is an important approach used by the Veterinary Services of the United States Department of Agriculture Animal and Plant Health Inspection Service to evaluate the potential effectiveness of different strategies for handling foot and mouth disease (FMD). Identifying the potential spread of FMD by modelling an outbreak, and then considering the impacts of FMD vaccination, is important in helping to inform decision-makers about the potential outcomes of vaccination programmes. The objective of this study was to evaluate emergency vaccination control strategies used in a simulated FMD outbreak in Minnesota. The North American Animal Disease Spread Model (NAADSM, Version 3.2.18) was used to simulate the outbreak. Large-scale (1,500 herds per day) emergency vaccination reduced the size of the modelled outbreak in both swine and dairy production types, but the effect was larger when the outbreak began in a dairy herd. Large-scale vaccination also overcame limitations caused by delays in vaccine delivery. Thus, even if vaccination did not begin until 21 days into the outbreak, large-scale vaccination still reduced the size and duration of the outbreak. The quantity of vaccine used was markedly larger when large-scale vaccination was used, compared with small-scale (50 herds per day) vaccine administration. In addition, the number of animals and herds vaccinated in an outbreak originating in a herd of swine was substantially lower than in an outbreak beginning in a herd of dairy cattle.

Evaluation of performance of bacterial culture of feces and serum ELISA across stages of Johne's disease in cattle using a Bayesian latent class model

The objective of this study was to evaluate the performance of bacterial culture of feces and serum ELISA to correctly identify cows with Mycobacterium avium ssp. paratuberculosis (MAP) at heavy, light, and non-fecal-shedding levels. A total of 29,785 parallel test results from bacterial culture of feces and serum ELISA were collected from 17 dairy herds in Minnesota, Pennsylvania, and Colorado. Samples were obtained from adult cows from dairy herds enrolled for up to 10 yr in the National Johne's Disease Demonstration Herd Project. A Bayesian latent class model was fitted to estimate the probabilities that bacterial culture of feces (using 72-h sedimentation or 30-min centrifugation methods) and serum ELISA results correctly identified cows as high positive, low positive, or negative given that cows were heavy, light, and non-shedders, respectively. The model assumed that no gold standard test was available and conditional independency existed between diagnostic tests. The estimated conditional probabilities that bacterial culture of feces correctly identified heavy shedders, light shedders, and non-shedders were 70.9, 32.0, and 98.5%, respectively. The same values for the serum ELISA were 60.6, 18.7, and 99.5%, respectively. Differences in diagnostic test performance were observed among states. These results improve the interpretation of results from bacterial culture of feces and serum ELISA for detection of MAP and MAP antibody (respectively), which can support on-farm infection control decisions and can be used to evaluate disease-testing strategies, taking into account the accuracy of these tests.

From network analysis to risk analysis--An approach to risk-based surveillance for bovine tuberculosis in Minnesota, US

Bovine tuberculosis (bTB) was first detected in 2005 in cattle in northwestern Minnesota (MN) through slaughter surveillance. By the end of 2008, 12 cattle herds were infected with bTB, and the main cause for infection was determined to be the movement of infected animals between herds. Bovine tuberculosis was contained in a smaller area in northwestern Minnesota classified as modified accredited (MA), corresponding to a prevalence inferior to 0.1% in cattle. From January 2008 to 2011, all cattle movements within the bTB MA were recorded electronically. The primary objectives of this study were to characterize cattle movements within this region and identify cattle herds with higher risk of bTB introduction based on network parameters and known risk factors from the published literature. During the period that data was collected, 57,460 cattle were moved in 3762 movements corresponding to permits issued to 682 premises, mostly representing private farms, sale yards, slaughter facilities and county or state fairs. Although sale yards represented less than 2% of the premises (nodes), 60% of the movements were to or from a sale yard. The network showed an overall density of 0.4%, a clustering coefficient of 14.6% and a betweenness centralization index of 12.7%, reflecting the low connectivity of this cattle network. The degree distribution showed that 20% of nodes performed 90% of the movements. Farms were ranked based on the total risk score and divided into high, medium, and low risk groups based on the score and its variability. The higher risk group included 14% (n=50) of the farms, corresponding to 80% of the cumulative risk for the farms in the bTB area. This analysis provides a baseline description about the contact structure of cattle movements in an area previously infected with bTB and develops a framework for a targeted surveillance approach for bTB to support future surveillance decisions.

Electron shell ionization of atoms with classical, relativistic scattering

We investigate forward scattering of ionization from neon, argon, and xenon in ultrahigh intensities of 2 × 10(19) W/cm(2). Comparisons between the gases reveal the energy of the outgoing photoelectron determines its momentum, which can be scattered as far forward as 45° from the laser wave vector k(laser) for energies greater than 1 MeV. The shell structure in the atom manifests itself as modulations in the photoelectron yield and the width of the angular distributions. We arrive at an agreement with theory by using an independent electron model for the atom, a dipole approximation for the bound state interaction, and a relativistic, three-dimensional, classical radiation field including the laser magnetic field. The studies provide the atomic physics within plasmas, radiation, and particle acceleration in ultrastrong fields.

Reduction in incidence of Johne's disease associated with implementation of a disease control program in Minnesota demonstration herds

This prospective longitudinal observational study was conducted to evaluate the effect of a standardized control program on the incidence of Johne's disease in 8 dairy herds in Minnesota. Depending on recruitment year, herds were followed for between 5 and 10 yr. Program compliance was evaluated using a cohort risk assessment score by birth cohort. Fecal samples from cows in study herds were tested annually using bacterial culture to detect Mycobacterium avium ssp. paratuberculosis (MAP), and serum samples from study cows were tested using an ELISA to detect antibodies to MAP. Clinical Johne's disease was also recorded. Cohort risk assessment score decreased along birth cohorts. Depending on the follow-up period in each herd, 5 to 8 birth cohorts were followed to describe changes in time to MAP bacterial culture positivity, serum ELISA positivity, MAP heavy shedding status, and clinical Johne's disease. The analysis of time to bacterial culture positivity, serum ELISA positivity, heavy fecal shedding status, and clinical Johne's disease using a time-dependent Cox regression indicated a reduction of the instantaneous hazard ratio by birth cohorts and by cohort risk score; however, the strength of association between the cohort risk score and each of the 4 disease outcomes decreased over time. The age at which the cows first tested positive for bacterial culture, serum ELISA, and heavy fecal shedding, and the age of the cows at onset of clinical Johne's disease signs remained constant for all birth cohorts. Based on herd risk scores, overall herds complied with the recommended management practices in the program. Results were consistent with a within-herd reduction of Johne's disease transmission, and that reduction was associated with herd-level management practices implemented as part of the control program.

A novel bipolar electric fence for excluding white-tailed deer from stored livestock feed

Where cattle (Bos taurus) and free-ranging white-tailed deer (Odocoileus virginianus) coexist, they frequently share space and resources, potentially resulting in damage to stores of livestock feed and risk of interspecies disease transmission. Preventing use of stored feed by deer can be an important objective in farm management, depending on amount of damage experienced and perceived risk of disease transmission. Woven wire fences (2.4 to 3.0 m high) are generally considered to be the most effective means for excluding deer. However, rapidly deployable temporary means of excluding deer could be useful, especially during late winter when deer are most physiologically stressed and motivated to consume feed meant for cattle. Thus, the objective of this study was to evaluate a novel 1.2-m-tall electric fence consisting of 4 strands of bipolar tape (not requiring separate ground wires or animal contact with ground) for excluding deer from artificially established feed piles during late winter 2008 in northwestern Minnesota. To induce deer to pause, investigate the fence, and receive negative stimuli before attempting to jump the fence, the bipolar tape was baited with a viscous fluid attractive to deer. The fence was estimated to be >80% effective at reducing deer presence at feed piles (10 treatment sites and 11 control sites) given the late winter to early spring conditions. Despite the efficacy, using the fence as a primary means of protecting stored feed from deer in areas with known disease transmission risk (e.g., presence of bovine tuberculosis) is not recommended because risk could remain unacceptably high if even low numbers of deer access stored feed. Yet, the fence could be effective as immediate protection of stored feed in winter before a more permanent and effective deterrence strategy, such as woven-wire fencing, could be installed during the subsequent summer. The fence would also be effective for reducing deer depredation of stored feed, as well as gardens, small orchards, or other localized or seasonal resources.

Long-Term Survival of Mycobacterium avium subsp. paratuberculosis in Fecal Samples Obtained from Naturally Infected Cows and Stored at -18°C and -70°C

The objective was to evaluate the survival of Mycobacterium paratuberculosis (Map) in naturally infected dairy cows feces under long periods of freezing at −18°C and −70°C. Samples were collected from cows previously tested positive with serum ELISA or fecal culture, or with clinical signs of Johne's disease. Samples were stored at −18°C and/or −70°C and recultured in Herrold's egg yolk media every 3–6 months. A proportional odds mixed model was used for data analysis. Sixty nine fecal samples were stored for different periods between September 2002 and January 2005. Of these, 45 (65%) were stored at −18°C and 24 (35%) at −70°C. Average number of days between repeated culture dates was 98 and 84 for −18°C and −70°C, respectively. Median number of repeated cultures was 6 and 4 for samples stored at −18°C and −70°C, respectively. After adjusting for initial sample bacterial load, the effects of temperature or number of thawing and refreezing cycles on Map viability were not significant. The probability that a sample decreases from high to moderate-low bacterial load and from moderate-low to negative bacterial load was 13.5% per month. Although this study found gradual reduction of Map concentration in stored fecal samples through time, overall survival in −18°C can ease fecal samples management in laboratories with low-processing capacity or lack of −70°C freezer.

Effect of Johne's disease status on reproduction and culling in dairy cattle

Among the costs attributed to Mycobacterium avium ssp. paratuberculosis (MAP) infection in dairy cattle, the effects on reproduction and culling are the least documented. To estimate the cost of MAP infections and Johne's disease in a dairy herd, the rates of calving and culling were calculated for cows in each stage of MAP infection relative to uninfected cows. Data from 6 commercial dairy herds, consisting of 2,818 cows with 2,754 calvings and 1,483 cullings, were used for analysis. Every cow in each study herd was tested regularly for MAP, and herds were followed for between 4 and 7 yr. An ordinal categorical variable for Johne's disease status [test-negative, low-positive (low-shedding or ELISA-positive only), or high-shedding] was defined as a time-dependent variable for all cows with at least 1 positive test result or 2 negative test results. A Cox regression model, stratified on herd and controlling for the time-dependent infection variable, was used to analyze time to culling. Nonshedding animals were significantly less likely to be culled in comparison with animals in the low-shedding or ELISA-positive category, and high-shedding animals had nonsignificantly higher culling rates than low-shedding or ELISA-positive animals. Time to calving was analyzed using a proportional rates model, an analog to the Andersen-Gill regression model suitable for recurrent event data, stratifying on herd and weighted to adjust for the dependent censoring caused by the culling effects described above. High-shedding animals had lower calving rates in comparison with low-shedding or ELISA-positive animals, which tended to have higher calving rates than test-negative animals.

Loss of income from cows shedding Mycobacterium avium subspecies paratuberculosis prior to calving compared with cows not shedding the organism on two Minnesota dairy farms

Quantification of the financial effect of Mycobacterium paratuberculosis infection on lactation performance is essential to encourage participation of dairy cattle producers in Johne's disease (JD) control programs. The objective of this study was to evaluate the differences in net income per lactation of cows shedding Mycobacterium paratuberculosis before calving compared with test-negative cows. Two Minnesota dairies were enrolled in the study and fecal samples were collected from 1,048 cows during the close-up period. Milk production, clinical diseases (other than clinical JD), and reproductive performance data were recorded for each cow. Overall, fecal-culture-positive (FCP) cows produced 1,355 kg less than fecal-culture-negative (FCN) cows. Fecal-culture-positive cows that survived their current lactation produced $276 less in milk income than cows that were FCN ($1,956 vs. $1,680; SD $526, $570). Fecal-culture-positive cows were 3.0 (95% confidence interval: 1.6-5.8) times more likely to be culled than FCN cows. The mean days open (number of days from calving to conception) was not statistically significant and the cost differences for clinical disease other than JD were small and neither statistically nor economically significant between FCP and FCN cows. Among all FCP cows, income over feed costs losses were $366 per cow per lactation compared with FCN cows. Among FCP nonculled cows, income over feed costs losses were $276 more compared with FCN cows and this difference was statistically significant. There was a total loss of $155 per lactation for nonculled FCP cows retained in the herd compared with FCN cows retained in the herd. Among culled cows, FCP cow losses were $50 less because of age at culling and $120 for reduced beef value. This totaled a loss of $441 for culled FCP cows compared with culled FCN cows. The losses as a result of lower lactation performance and early culling from the herd should alarm dairy producers and motivate them to implement the appropriate control measures for the disease.

Evaluation of the Voluntary Johne's Disease Herd Status Program as a source of replacement cattle

The objectives of this study were to evaluate the perceived value that enrolled producers gained from participation in the Voluntary Johne's Disease Herd Status Program (VJDHSP), and to evaluate the risk of infection with Mycobacterium avium ssp. paratuberculosis (MAP) of cattle reared in a presumed Johne's free environment vs. cattle raised in an environment of unknown Johne's status. Producers enrolled in level 3 or 4 of the VJDHSP (98 and 99% probability, respectively, of being free from MAP infection) were interviewed via telephone. Producers were asked questions pertaining to their participation in the VJDHSP, and asked to identify herds to which they had sold replacement heifers. These cattle were presumed to be uninfected before sale. Fifty-nine cattle (identified as having been purchased into infected herds as heifers) were identified as having been raised in uninfected herds and sold to producers with herds of unknown Johne's disease status. On the purchasing farm, fecal and blood samples were collected from each cow of VJDHSP origin and 3 randomly selected home-reared cows per VJDHSP cow matched by lactation as controls. Samples were tested using commercial ELISA (serum) and bacterial culture (feces). Results indicated that enrolled producers saw value in VJDHSP participation, and that cattle reared in VJDHSP herds were less likely to be infected with MAP than herdmates as measured by serum ELISA MAP antibody and by fecal culture. This study provides evidence of the value of the VJDHSP in providing economic value to participants and supports the promotion of VJDHSP herds as a source of replacement cattle of low infection risk for MAP.

Prevalence of antimicrobial resistance among Salmonella on midwest and northeast USA dairy farms

The objective of this study was to determine the prevalence of antimicrobial resistance among Salmonella isolated from dairy herds in New York, Minnesota, Michigan, and Wisconsin, USA. Serogroup and antimicrobial susceptibility characteristics were determined for Salmonella from cattle and environmental samples collected during August 2000-October 2001 as part of a longitudinal study where 129 herds were visited at 2-month intervals. Salmonella isolates were tested (using a broth microdilution method) for susceptibility to amoxicillin/clavulanic acid, ampicillin, ceftiofur, ceftriaxone, cephalothin, chloramphenicol, ciprofloxacin, gentamicin, kanamycin, nalidixic acid, streptomycin, sulfamethoxazole, tetracycline, and trimethoprim/sulfamethoxazole. Of the 1506 isolates tested for minimum inhibitory concentrations to these 14 antimicrobial agents, 81.2% were pan-susceptible and for most herds (81.6%) the predominant antimicrobial resistance pattern was pan-susceptible. At least 1 Salmonella isolate resistant to 5 or more antimicrobial agents was found on 23.6% of herds. This resistance phenotype was most common among serogroups B and E1 and among samples from calves and farmer-designated sick cows. Resistant samples most frequently exhibited resistance to tetracycline, streptomycin, and/or ampicillin. No samples were resistant to ceftriaxone (though 13 were in the intermediate range), and very few samples were resistant to ciprofloxacin (n=1), nalidixic acid (n=5), or trimethoprim/sulfamethoxazole (n=7).

Antimicrobial Susceptibility of Salmonella from Organic and Conventional Dairy Farms

The objective of this study was to compare antimicrobial susceptibility of Salmonella isolated from conventional and organic dairy farms in the Midwest and Northeast United States. Environmental and fecal samples were collected from organic (n = 26) and conventional (n = 69) farms in Michigan, Minnesota, New York, and Wisconsin every 2 mo from August 2000 to October 2001. Salmonella isolates (n = 1,243) were tested using a broth microdilution method for susceptibility to amoxicillin-clavulanic acid, ampicillin, ceftiofur, ceftriaxone, cephalothin, chloramphenicol, ciprofloxacin, gentamicin, kanamycin, nalidixic acid, streptomycin, sulfamethoxazole, tetracycline, and trimethoprim-sulfamethoxazole. Herd-level logistic regression and logistic proportional hazards multivariable models were used to examine the association between farm management type and susceptibility to antimicrobial agents. For most antimicrobial agents tested, susceptibility of Salmonella isolates was similar on organic and conventional herds when controlling for herd size and state. Conventional farms were more likely to have at least one Salmonella isolate resistant to streptomycin using logistic regression (odds ratio = 7.5; 95% confidence interval = 1.7-5.4). Conventional farms were more likely to have Salmonella isolates with greater resistance to streptomycin (odds ratio = 5.4; 95% confidence interval = 1.5-19.0) and sulfamethoxazole (odds ratio = 4.2; 95% confidence interval = 1.2-14.1) using logistic proportional hazards models. Although not statistically significant, conventional farms tended to be more likely to have at least one Salmonella isolate resistant to 5 or more antimicrobial agents when compared with organic farms.

Herd-level factors associated with isolation of Salmonella in a multi-state study of conventional and organic dairy farms

The objective of this study was to evaluate associations between herd characteristics and the isolation of Salmonella from dairy cows in Minnesota, Wisconsin, Michigan, and New York. Study farms were 129 conventional and organic farms enrolled without regard to previous history of Salmonella infection. Herds were sampled at 2-month intervals over a 1-year period. This is the largest study to date on Salmonella shedding in dairy cows and the only study evaluating herd-level risk factors using longitudinal sampling to characterize Salmonella shedding on dairy farms. Salmonella was isolated in fecal samples from 1026 (4.9%) of 20,089 cows. Over the course of the study, 113 (87.6%) of 129 farms had at least one positive cow sample. Multi-variable logistic regression using the generalized estimating equations approach was used to test the association between herd-level risk factors and the dependent variable of within-herd prevalence by visit (number of Salmonella-positive cows/number of cows sampled) after adjustment for effects of herd size, season, state of origin, and the multiple sampling occasions per herd. Factors retained in the final model included lack of use of tiestall or stanchion facilities to house lactating cows (OR=1.9; 95% CI: 1.1-3.3), not storing all purchased concentrate or protein feeds in an enclosed building (OR=2.5; 95% CI: 1.3-4.9), not using monensin in weaned calf or bred heifer diets (OR=3.2; 95% CI: 2.0-5.4), access of lactating or dry cows to surface water (e.g., lake, pond, river, or stream) (OR=2.3; 95% CI: 1.3-3.9), disposal of manure in liquid form (slurry or irrigation, as opposed to disposal of manure by broadcast/solid spreader only) on owned or rented land (OR=1.8; 95% CI: 1.3-3.9), and cows eating or grazing of roughage from fields where manure was applied in solid or liquid form and not plowed under during the same growing season (OR=1.8; 95% CI: 1.0-3.0). A seasonal association was also present as cows were more likely to be Salmonella-positive in summer, spring, and fall compared to winter. Herd size was not associated with Salmonella shedding in the final multi-variable model. The herd-level risk factors identified in this study could potentially be implemented in Salmonella control programs on dairy farms.

Herd-level factors associated with isolation of Salmonella in a multi-state study of conventional and organic dairy farms

The objective of this study was to evaluate associations between herd-level factors and the isolation of Salmonella in calves from dairy farms in Minnesota, Wisconsin, Michigan and New York. Study farms were 129 conventional and organic farms enrolled without regard to previous history of Salmonella infection. Herds were sampled at 2-month intervals over a 1-year period. Salmonella was isolated in fecal samples from 176 (3.8%) of 4673 preweaned calves with 40 (31.0%) of 129 farms having at least one positive calf sample over the course of the study. Multivariable logistic regression using the generalized estimating equations approach was used to evaluate risk factors for Salmonella shedding after adjustment for effects of herd size, season, state of origin and the multiple sampling occasions per herd. Factors retained in the final model that were associated with an increased odds for Salmonella shedding were lack of routine feeding of milk replacer containing antimicrobials to preweaned calves (OR=2.8, 95% CI: 1.4, 5.8), use of maternity housing as a hospital area for sick cows more than once a month (OR=2.1, 95% CI: 1.1, 4.0), and cow prevalence level by visit, categorized into the following four-levels: > or =20% (OR=11.6, 95% CI: 5.7, 23.7), 10-19.9% (OR=4.7, 95% CI: 2.0, 11.5), 0.1-9.9% (OR=3.6, 95% CI: 1.5, 8.7) and 0% (reference level). Herd size was not associated with Salmonella shedding in the final multivariable model.

Cattle and environmental sample-level factors associated with the presence of Salmonella in a multi-state study of conventional and organic dairy farms

The objective of this study was to evaluate associations between cattle-level factors and environmental samples with the isolation of Salmonella from dairy farms in Minnesota, Wisconsin, Michigan, and New York. The study farms included 129 conventional and organic farms enrolled without regard to previous history of Salmonella infection. Herds were sampled at two-month intervals over a one-year period. Cattle groups more likely to be associated with Salmonella shedding (compared to preweaned calves) were cows designated as sick by farm personnel (OR=2.5, 95% CI: 1.7, 3.7), cows within 14 days of calving (OR=1.8, 95% CI: 1.1, 2.8), and cows due for culling within 14 days (OR=1.9, 95% CI: 1.0, 3.4). State of origin was also associated with the presence of Salmonella in samples from cattle and the farm environment; Midwestern states were more likely to have Salmonella-positive samples compared to New York. Cattle treated with antimicrobials within 14 days of sampling were more likely to be Salmonella-negative compared with nontreated cattle (OR=2.0, 95% CI: 1.1, 3.4). Farms with at least 100 cows were more likely to have Salmonella-positive cattle compared with smaller farms (OR=2.6, 95% CI: 1.4, 4.6). Season was associated with Salmonella shedding in cattle, and compared to the winter period, summer had the highest odds for shedding (OR=2.4, 95% CI: 1.5, 3.7), followed by fall (OR=1.9, 95% CI: 1.2, 3.1) and spring (OR=1.8, 95% CI: 1.2, 2.6). Environmental samples significantly more likely to be Salmonella-positive (compared to bulk tank milk) included, in descending order, samples from sick pens (OR=7.4, 95% CI: 3.4, 15.8), manure storage areas (OR=6.4, 95% CI: 3.5, 11.7), maternity pens (OR=4.2, 95% CI: 2.2, 8.1), haircoats of cows due to be culled (OR=3.9, 95% CI: 2.2, 7.7), milk filters (OR=3.3, 95% CI: 1.8, 6.0), cow waterers (OR=2.8, 95% CI: 1.4, 5.7), calf pens (OR=2.7, 95% CI: 1.3, 5.3), and bird droppings from cow housing (OR=2.4, 95% CI: 1.3, 4.4). Parity, stage of lactation, and calf age were not associated with Salmonella shedding.

The Distribution of Mycobacterium avium ssp. paratuberculosis in the Environment Surrounding Minnesota Dairy Farms

The objective of this study was to characterize the distribution of Mycobacterium paratuberculosis (Map) in the environment of infected and uninfected Minnesota dairy farms. Eighty herds known to be infected from Minnesota's Johne's Disease Control Program (JDCP) and 28 herds known to be uninfected from Minnesota Voluntary Johne's Disease Herd Status Program (VJDHSP) were sampled. Fecal samples from up to 100 cows in each herd were cultured in pools of 5 cows. Two environmental samples were obtained from each farm from various locations. All samples were tested using bacterial culture for Map. Eighty percent of the JDCP herds had at least one positive pool. Environmental samples were cultured positive in 78% of the JDCP herds. Two (7%) of the VJDHSP herds had one positive pool, and one herd had one positive environmental sample. Environmental samples were cultured positive in cow alleyways (77% of the herds), manure storage (68%), calving area (21%), sick cow pen (18%), water runoff (6%), and postweaned calves areas (3%). There was an association between maximum level of colonies per tube from cow alleyways and manure storage and fecal pool prevalence. Herds with both areas cultured negative were estimated to have 0.3 to 4% fecal pool prevalence. Herds with both areas having a heavy load of bacteria were estimated to have 53 to 73% fecal pool prevalence. The study results indicate that targeted sampling of cow alleyways and manure storage areas appears to be an alternative strategy for herd screening and Johne's infection status assessment and for estimating herd fecal prevalence.

Management practices and reported antimicrobial usage on conventional and organic dairy farms

The primary objective was to compare reported antimicrobial usage between conventional and organic dairy farms. A secondary objective was to contrast selected management characteristics of conventional and organic dairy herds. A questionnaire was administered on site to selected dairy farmers located in Michigan, Minnesota, New York, and Wisconsin. Organic herds (n = 32) were smaller and produced less milk than conventional herds (n = 99). Lactating cows in organic dairies were more likely to be housed in tie stalls, whereas most conventional dairies housed cows in free stalls and milked in a parlor. Total mixed rations and purchased feeds were used on more conventional dairy farms compared with organic dairy farms. Conventional dairy producers were more likely to use advice from veterinarians for recommendations of treatment, and organic dairy producers were more likely to rely on advice from other farmers. Based on recall of antibiotic usage in the previous 60 d, 5.1, 84.9, 9.1, and 0.9% of farmers with conventional herds reported treatment of none, 1 to 10%, 11 to 25%, and >25% of milk cows, respectively. Most organic farmers (90.6%) reported no antibiotic treatments of milk cows, whereas 9.4% reported treating 1 to 10% of milk cows. Ceftiofur was the most commonly reported antibiotic for both farm types. Milk replacer containing antibiotics was reportedly used on 49.5% of conventional herds but only on one organic herd (3.1%). Antibiotics were used in heifer calves on 74.7% of conventional herds versus 21.9% of organic herds. Antibiotics to treat mastitis were used on 79.8% of conventional herds but on none of the organic herds. Most organic farms were in compliance with standards in advance of implementation of regulations.

Association between bovine-leukosis virus seroprevalence and herd-level productivity on US dairy farms

Bovine-leukosis virus (BLV; also termed 'bovine-leukemia virus') is a retrovirus that primarily affects lymphoid tissue of dairy and beef cattle. Our objective was to investigate the association between BLV infection and annual value of production (AVP) on dairy herds within the United States, as part of the USDA National Animal Health Monitoring System's 1996 dairy study. 1006 herds (in 20 states) with at least 30 dairy cows were interviewed during 1996. The agar-gel immunodiffusion test was used to detect serum antibodies to BLV. 10-40 cows from each herd were tested and each tested cow was classified as negative or positive based on results of a single test. A multivariable regression model was used with the 976 herds with complete data for analysis. When compared to herds with no test-positive cows, herds with test-positive cows produced 218 kg per cow (i.e. 3%) less milk. The average reduction in AVP was $59 per cow for test-positive herds relative to test-negative herds. For the dairy industry as a whole, BLV seropositivity was associated with loss to producers of $285 million and $240 million for consumers. Most of this $525 million industry loss was due to reduced milk production in test-positive herds.

Evaluation of herd sampling for Salmonella isolation on midwest and northeast US dairy farms

Epidemiologic investigations of Salmonella infections in dairy cattle often rely on testing fecal samples from individual animals or samples from other farm sources to determine herd infection status. The objectives of this project were to evaluate the effect of sampling frequency on Salmonella isolation and to compare Salmonella isolation and serogroup classification among sample sources on 12 US dairy farms sampled weekly for 7-8 weeks. Three herds per state were enrolled from Michigan, Minnesota, New York and Wisconsin based upon predefined herd-size criteria. Weekly samples were obtained from cattle, bulk tank milk, milk filters, water and feed sources and environmental sites. Samples were submitted to a central laboratory for isolation of Salmonella using standard laboratory procedures. The herd average number of cattle fecal samples collected ranged from 26 to 58 per week. Salmonella was isolated from 9.3% of 4049 fecal samples collected from cattle and 12.9% of 811 samples from other sources. Serogroup C1 was found in more than half of the samples and multiple serogroups were identified among isolates from the same samples and farms. The percentage of herd visits with at least one Salmonella isolate from cattle fecal samples increased with overall herd prevalence of fecal shedding. Only the three herds with an average fecal shedding prevalence of more than 15% had over 85% of weekly visits with at least one positive fecal sample. The prevalence of fecal shedding from different groups of cattle varied widely among herds showing that herds with infected cattle may be classified incorrectly if only one age group is tested. Testing environmental sample sources was more efficient for identifying infected premises than using individual cattle fecal samples.

Effect of on-farm commercial batch pasteurization of colostrum on colostrum and serum immunoglobulin concentrations in dairy calves

The objectives were to describe the effect of on-farm commercial batch pasteurization on immunoglobulin (IgG) concentrations and the fluid and feeding characteristics of colostrum and to compare serum IgG concentrations in calves fed fresh versus pasteurized colostrum. Newborn calves (123) were systematically allocated to dietary treatments of either fresh or pasteurized colostrum at both the first and second colostrum feedings. The IgG concentrations were measured for batches of colostrum fed fresh and in pre and postpasteurized samples for batches of colostrum fed after being pasteurized and in calf serum. Pasteurization reduced colostrum IgG concentration, with the percentage reduction averaging 58.5 and 23.6% for 95-L and 57-L batches, respectively. Pasteurizing high quality colostrum in 57-L (vs. 95-L) batches resulted in higher IgG concentrations in the end product. Pasteurization of 57-L batches produced colostrum of normal or only mildly thickened consistency that could be fed to calves. Serum IgG concentrations were higher for calves fed fresh colostrum and for calves with a shorter time interval (< or = 6 h) between first and second colostrum feedings. After controlling for the time interval between feedings, serum IgG concentrations were significantly higher for 40 calves fed unpasteurized (19.1 mg/ml) vs. 55 calves fed pasteurized colostrum (9.7 mg/ml) for calves fed 2 L at first feeding. By contrast, there was no difference in serum IgG concentrations between 8 calves fed unpasteurized (16.1 mg/ml) and 20 calves fed pasteurized colostrum (13.5 mg/ml) after calves were fed 4 L at the first feeding. While the latter results suggest that pasteurizing colostrum may work for producers with excellent colostrum management, these results are preliminary and should be interpreted with caution, given the fewer number of calves and batches of colostrum involved with this second comparison.

Relationships between fecal culture, ELISA, and bulk tank milk test results for Johne's disease in US dairy herds

Objectives were to estimate percentages of seropositive herds with cows shedding Mycobacterium paratuberculosis in feces and milk, and to estimate sensitivity, specificity, and predictive value of an ELISA relative to fecal culture. Dairy cows (n = 712) were randomly selected from 61 herds previously identified by ELISA as positive for Johne's disease. Fecal and bulk tank milk samples (n = 52 of 61 herds) were obtained from 10 states in the United States. Fecal samples were processed by a double centrifugation, double decontamination culture procedure. Milk samples were processed for both culture and DNA analysis by using polymerase chain reaction (PCR). Of 24 herds with at least three cows that had tested ELISA-positive, 79% were also culture-positive, compared with 18 of 37 herds with one or two ELISA-positive cows. Both fecal-culture and ELISA results were available on 651 cows; only 25% of cows that were fecal-culture positive also tested positive by ELISA and over 6% of cows that were fecal-culture negative tested ELISA-positive. Milk samples all cultured negative, but analysis of milk samples by PCR resulted in 68% of herds positive for M. paratuberculosis DNA including 24 of 31 herds with positive fecal cultures and 11 of 21 herds with negative fecal cultures. Sensitivity and specificity of the ELISA compared with fecal culture is lower than previously reported and perhaps best used in screening herds because of limited efficacy to predict infection in individual cows. In addition, contamination of bulk tank milk samples with M. paratuberculosis does occur in seropositive herds, even in some with negative fecal cultures.

Prevalence of antibodies against Mycobacterium avium subsp paratuberculosis among beef cow-calf herds

OBJECTIVE

To estimate the prevalence of Mycobacterium avium subsp paratuberculosis infection among cows on beef operations in the United States.

DESIGN

Cross-sectional seroprevalence study. Sample Population-A convenience sample of 380 herds in 21 states.

PROCEDURES

Serum samples were obtained from 10,371 cows and tested for antibodies to M avium subsp paratuberculosis with a commercial ELISA. Producers were interviewed to collect data on herd management practices.

RESULTS

30 (7.9%) herds had 1 or more animals for which results of the ELISA were positive; 40 (0.4%) of the individual cow samples yielded positive results. None of the herd management practices studied were found to be associated with whether any animals in the herd would be positive for antibodies to M avium subsp paratuberculosis.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that the prevalence of antibodies to M avium subsp paratuberculosis among beef cows in the United States is low. Herds with seropositive animals were widely distributed geographically.

Variance estimation for population attributable risk in a complex cross-sectional animal health survey

Population attributable risk estimates offer a method of combining information on population exposure and disease risk factors into a single measure. Univariate and multivariable methods exist for calculating point estimates and variances under the assumption of equal sampling probabilities. National Animal Health Monitoring System national studies typically use a complex survey design (where selection probabilities vary by design strata), which makes use of these methods of calculating variance inappropriate. We suggest the use of a method called "delete-a-group" jackknife to estimate the variance of population attributable risk when a complex survey design has been implemented. We demonstrate the method using an example of Johne's disease. Advantages of the "delete-a-group" jackknife method include simplicity of implementation and flexibility to estimate variance for any point estimate of interest.

Fecal shedding of Salmonella spp. by dairy cows on farm and at cull cow markets

As part of a national study of the U.S. dairy cow population, fecal samples were collected from representative cows on 91 dairies and 97 cull dairy cow markets in 19 states. Salmonella spp. were recovered from 5.4% of milk cows, 18.1% of milk cows expected to be culled within 7 days, and 14.9% of culled dairy cows at markets. On a premise basis, Salmonella shedding in milk cows was detected on 21.1% of dairies and 66% of cull dairy cow markets. The percentage of herds with at least one cow with detectable Salmonella fecal shedding was higher during the sampling period from May through July, in herds with at least 100 milk cows, and in herds in the South region. The most common Salmonella serogroups isolated were E (30.8% of isolates) and C1 (28.6%); the most common serotypes isolated were Salmonella Montevideo (21.5% of isolates), Salmonella Cerro (13.3%), and Salmonella Kentucky (8.5%). Fecal shedding of Salmonella Typhimurium or Salmonella Typhimurium var. copenhagen was infrequent (2.8% of isolates). Most isolates (88.9%) were susceptible to all 17 antimicrobials evaluated; multiple resistance was an infrequent occurrence. This study provides information describing the distribution of Salmonella fecal shedding from dairy cows on farm and at markets and will serve as a baseline for future studies.

ELISA and fecal culture for paratuberculosis (Johne's disease): sensitivity and specificity of each method

The sensitivity and specificity of the ELISA and fecal culture tests for paratuberculosis in dairy cattle are examined. ELISA and fecal culture data from seven dairy herds where both fecal cultures and ELISA testing was done concurrently are included. A cohort of 954 cattle including 697 parturient adults, cultured every 6 months from 10 herds followed over 4 years served as the basis to determine fecal culture sensitivity. The fecal culture technique utilized a 2g sample with centrifugation and double incubation. Of the 954 cattle cohort of all ages (calf to adult) that were fecal sampled on the first herd visit, 79 were culture positive. An additional 131 animals were detected as culture positive over the next seven tests at 6-month intervals. The sensitivity of fecal culture to detect infected cattle on the first sampling was 38%. Of the 697 parturient cattle cohort, 67 were positive on the first fecal culture, while an additional 91 adult cattle were culture positive over the next seven tests, resulting in a sensitivity of 42% on the first culture of the total animals identified as culture positive. Animals culled from the herds prior to being detected as infected and animals always fecal culture negative with culture positive tissues at slaughter are not included in the calculations. Both groups of infected cattle will lower the apparent sensitivity of fecal culture. Infected dairy herds tested concurrently with both fecal culture and ELISA usually resulted in more than twofold positive animals by culture compared to ELISA. The classification of infected cattle by the extent of shedding of Mycobacterium paratuberculosis in the feces helps define the relative proportion of cattle in each group and therefore the likelihood of detection by the ELISA test. ELISA has a higher sensitivity in animals with a heavier bacterial load, i.e. high shedders (75%) compared to low shedders (15%). Repeated testing of infected herds identifies a higher proportion of low shedders which are more likely to be ELISA negative. Thus, the sensitivity of the ELISA test decreases with repeated herd testing over time, since heavy shedders will be culled first from the herds.

Biosecurity on dairy operations: hazards and risks

The objective here was to present a model for considering biosecurity related to infectious diseases on US dairy operations using a risk assessment framework. With the example of an important dairy cattle pathogen (Mycobacterium paratuberculosis), I followed risk assessment steps to characterize risks related to the use of certain management practices and possible risk reduction within an infectious disease biosecurity program. Biosecurity practices focus on the prevention of introduction of these pathogens to the dairy, and estimates of the risks associated with introduction of different sources of cattle are presented. In addition, biosecurity practices also limit the transmission of these pathogens within an infected dairy operation, especially those focused on sick cow management, calving area management, and manure management. Recent information from the National Animal Health Monitoring System (NAHMS) Dairy 96 Study indicates that many of these practices have not been adopted on US dairy operations, indicating both risk of disease and opportunity for animal health improvement.

Herd-level risk factors for infection with Mycobacterium paratuberculosis in US dairies and association between familiarity of the herd manager with the disease or prior diagnosis of the disease in that herd and use of preventive measures

OBJECTIVE

To evaluate associations among herd infection status, herd management practices, and familiarity of the herd manager with Mycobacterium paratuberculosis (Johne's disease) or prior disease diagnosis in that herd to support development of Johne's disease-control programs.

DESIGN

Population-based cross-sectional study.

SAMPLE POPULATION

1,004 US dairies, each with > or = 30 cows, representing 79.4% of US dairy cows.

PROCEDURE

Questionnaires were administered to dairy managers, and blood samples were collected from cows during herd visits. Sera were tested for antibodies to M paratuberculosis, using a commercially available ELISA. Multivariable logistic regression analyses were used to evaluate associations between use of management practices, herd disease status, and familiarity of the manager with Johne's disease or prior diagnosis of Johne's disease in that herd.

RESULTS

Results from serologic testing revealed that 3.4% of cows and 21.6% of dairy herds were infected with M paratuberculosis. Factors associated with infection included number of cows in herd, region of country, percentage of cows born at other dairies, group housing for periparturient cows, and group housing for preweaned calves. Few preventive practices were positively associated with prior diagnosis of Johne's disease (time of separation of newborn calf from dam) or familiarity of the manager with the disease (teats and udder washed before colostrum collected).

CONCLUSIONS AND CLINICAL RELEVANCE

Risk factors associated with Johne's disease in this study confirmed those management practices generally recommended for disease control. An educational problem, however, is the finding that herd managers familiar with Johne's disease generally use management practices similar to those used by managers unfamiliar with the disease.

Fecal shedding of Campylobacter and Arcobacter spp. in dairy cattle

Campylobacter jejuni, Campylobacter coli, and Arcobacter spp. were detected in feces of healthy dairy cows by highly specific multiplex-PCR assays. For C. jejuni, at this one-time sampling, cows from 80.6% of farm operations (n = 31) and 37.7% of individual dairy cattle fecal samples (n = 2,085) were positive. Farm management factors were correlated with prevalence in herds in which >25% of cows were positive for C. jejuni. Statistical significance was set at a P of 0.20. Using these criteria, application of manure with broadcast spreaders (P = 0.17), feeding of whole cottonseed or hulls (P = 0.17) or alfalfa (P = 0.15), and accessibility of feed to birds (P = 0.17) were identified as possible risk factors for C. jejuni infection. C. coli was detected in at least one animal in 19.4% of operations and 1.8% of individual cows (n = 2,085). At the herd level, use of broadcaster spreaders was not a risk factor for C. coli infection. For Arcobacter, cows from 71% of dairy operations (n = 31) and 14.3% of individual dairy cattle fecal samples (n = 1,682) were positive. At the herd level, for Arcobacter spp., feeding of alfalfa (P = 0.11) and use of individual waterers (P = 0.19) were protective. This is the first description of Arcobacter spp. in clinically healthy dairy cattle and the first attempt to correlate their presence with C. jejuni.

Risk factors for fecal shedding of Salmonella in 91 US dairy herds in 1996

In 1996, data on management practices used on US dairy operations were collected and analyzed for association with fecal shedding of Salmonella by dairy cows. A total of 4299 fecal samples from 91 herds was cultured for Salmonella isolation. Herd-size (adjusted odds ratios (OR) = 5.8, 95% CI 1.1, 31.3), region (OR = 5.7, CI 1.4, 23.5), use of flush water systems (OR = 3.5, CI 0.9, 14.7), and feeding brewers' products to lactating cows (OR = 3.4, CI 0.9, 12.9) were identified as the most important predictive risk factors. The population attributable risks (PARs) for herd-size, region, flush water system, and feeding brewers' products to lactating cows were 0.76, 0.46, 0.37, and 0.42, respectively. The estimated PAR for all four risk factors combined was 0.95. The effects of these factors need to be more-closely evaluated in more-controlled studies, in order to develop intervention programs that reduce Salmonella shedding.

Syphilitic lymphadenopathy. Histology and human immunodeficiency virus status

Few reports on syphilitic lymphadenopathy have appeared in 20 years, and none have compared findings in patients with and without human immunodeficiency virus (HIV) infection, despite the recent epidemic spread of syphilis and HIV. Twelve cases of syphilitic lymphadenopathy were studied and grouped according to HIV status. Patients were 21 to 62 years old (median, 29 years); 7 were men, 5 were women. Biopsy sites were cervical (7 cases), inguinal (4), and axillary (1) lymph nodes. All patients had evidence of syphilis. Rapid plasma reagin titers ranged from 1:32 to 1:512. Treponemal hemagglutination was positive in all cases tested. Spirochetes were found with Steiner staining in 2 cases. HIV testing was positive in 4, negative in 2, and unknown in 6 cases. Lymph nodes were enlarged and often fragmented due to capsular fibrosis and chronic inflammation, with focal obliteration of the subcapsular sinus. Follicular and interfollicular hyperplasia was seen in all cases and was usually marked, with prominent vascular proliferation, plasma cells, immuno-blasts, histiocytes, and occasional neutrophils. Follicle lysis and granulomas suggestive of unconfirmed toxoplasmosis were each seen in 1 case, and Kaposi sarcoma in 2, all in HIV-positive patients. Lymphoplasmacytic infiltration was marked, especially in interfollicular areas, with peri-vascular plasma cell cuffing in all cases and obliterative endarteritis in about half (7 of 12, 56%). Immunostaining for CD45RO (UCHL-1), CD20 (L26), kappa, lambda, and CD68 (Kp-1) revealed a mixed population of T cells, polyclonal B cells, and interfollicular histiocytes. Distribution of T and B cells (immunoarchitecture) was essentially normal and similar in all cases, regardless of HIV status. Syphilis produces essentially identical findings in lymph nodes in both HIV-positive and HIV-negative patients. The morphologic findings described should prompt evaluation for infection with Treponema pallidum and, in light of the current epidemic, HIV.

Herd-level economic losses associated with Johne's disease on US dairy operations

Johne's disease ('paratuberculosis') is a chronic, infectious, wasting disease that affects dairy cattle. Estimation of its impact on herd productivity and corresponding economic loss on US dairy operations was part of the USDA National Animal Health Monitoring System's (NAHMS) 1996 national dairy study. Johne's-positive herds experience an economic loss of almost US$ 100 per cow when compared to Johne's-negative herds due to reduced milk production and increased cow-replacement costs. For Johne's-positive herds that reported at least 10% of their cull cows as having clinical signs consistent with Johne's disease, economic losses were over US$ 200 per cow. These high-prevalence herds experienced reduced milk production of over 700 kg per cow, culled more cows but had lower cull-cow revenues, and had greater cow mortality than Johne's-negative herds. Averaged across all herds, Johne's disease costs the US dairy industry, in reduced productivity, US$ 22 to US$ 27 per cow or US$ 200 to US$ 250 million annually.

Papillomatous digital dermatitis and associated risk factors in US dairy herds

The objective of this study was to describe the incidence of papillomatous digital dermatitis in the US (including regional and herd size patterns) and to evaluate specific herd-level management factors associated with high incidence of digital dermatitis in US dairy herds. The study design was a population-based cross-sectional survey. US dairy operations with at least 30 cows in 20 states, representing 79% of US dairy cows, were sampled. On participant operations, a questionnaire was administered by veterinary medical officer or animal-health technicians on-farm to dairy managers. Papillomatous digital dermatitis was reported in milk cows in the previous 12 months from 43.5% of US dairy herds. Seventy-eight percent of affected herds reported that their first cases occurred in 1993 or later. Regions of the USA with the highest percent of herds affected included the Southwest, Northwest, and Northeast. Factors associated with high (> 5%) incidence of papillomatous digital dermatitis included region, herd size, type of land lactating cows accessed on a daily basis, flooring type where lactating cows walked, percent of cows born off the operation, use of a primary hoof trimmer who trimmed cows' hooves on other operations, and lack of washing of hoof-trimming equipment between cows. Papillomatous digital dermatitis has been recently reported from dairy herds across the US. This study suggests that a high percentage of herds with digital dermatitis could be prevented. Management strategies to potentially prevent or reduce incidence of digital dermatitis on dairy operations include those related to biosecurity and 'cow hoof' environmental conditions.

Key health issues for dairy cattle--new and old

The objective of this paper is to use available information to evaluate the relative importance of various health issues affecting dairy cattle. In addition to traditional ranking using evaluation methods based on impacts to animal productivity, this paper considers zoonotic risks, international trade implications, and animal welfare concerns. Traditional production costs rank mastitis, reproductive problems, and lameness as the top dairy cattle diseases. When the other areas of importance are included, the top-ranked diseases change to include salmonella, Johne's disease, bovine viral diarrhea-associated disease, and mastitis. Researchers in the dairy industry may want to reevaluate their criteria for setting research priorities to include zoonotic risks, international trade implications, and animal welfare concerns.

Genetic analysis of clinical lameness in dairy cattle

Scores for clinical lameness from two separate studies were combined, and genetic parameters were estimated based on linear and threshold models. Cows were from 24 herds in Minnesota, Wisconsin, and Virginia. To evaluate clinical lameness, cows were observed walking and were assigned a score between 0 and 4 (where 0 = no observable problems to 4 = inability to walk). Data included 1624 records on 1342 cows. The models included fixed effects of herd visit, parity, and stage of lactation. Random effects were additive genetics, permanent environment to account for repeated records, and residual. Estimates of heritability were 0.10 and 0.22 from the linear and threshold models, respectively. The correlation between ETA from linear and threshold models based on all animals was 0.974. Deregressed ETA of sires and REML were used to estimate genetic correlations between clinical lameness and conformation traits. Among the type traits, foot angle, rear legs (rear view), and rump width had strongest associations with clinical lameness; absolute values for genetic correlations between these traits and clinical lameness were approximately 0.65. Low foot angle, hocking in, and wide rumps were associated with increased clinical lameness. Correlations with strength and body depth ranged from 0.20 to 0.43, indicating that heavier cows were more prone to clinical lameness.

Factors in the emergence of food borne diseases

Food borne diseases are an important public health problem. Over the past two decades, the epidemiology of food borne diseases has changed rapidly as a consequence of changes in the social environment and the ability of pathogens to adapt to new niches. Several newly recognized pathogens have emerged and well-recognized pathogens have increased in prevalence or become associated with new food vehicles. Several factors have contributed to the changing patterns of food borne diseases, and addressing food borne diseases will require rapid surveillance and effective prevention strategies. This article examines these factors and briefly addresses prevention and control of food borne diseases.