Cost-benefit of implementing a participatory extension model for improving on-farm adoption of Johne's disease control recommendations.

The objective of this study was to perform a cost-benefit analysis (CBA) of a participatory extension model, called Ontario Focus Farms (FF), which was designed to facilitate the adoption of on-farm management practices to control Johne's disease (JD) on Ontario (ON) dairy farms. Partial budget models were developed to estimate the annual herd cost of JD on an average 78-cow Ontario dairy herd and the annual herd cost of neonatal calf diarrhea (NCD). With these estimates, a CBA was developed to assess the simulated net benefits of implementing various on-farm management scenarios (i.e., implementing 1, 2, or 3 of the following: calf feeding, maternity pen management, maternity area structure changes), where the benefits represent a reduction in the annual cost of JD and NCD. These models informed the final CBA assessing the net benefits of FF implementation over a 10-yr period. All monetary values are reported in Canadian dollars (Can$; where 1 Can$ = 0.823 US$ at the time of the study). The annual herd cost of JD was estimated to be $3,242 ($41.56/cow), and that of NCD was estimated to be $1,390 ($36/heifer calf). When farms were expected to have both JD and NCD, all scenarios, when implemented over a 10-yr period, yielded positive net benefits ranging from $439 to $2,543 per farm when changes to maternity area structure were combined with calf feeding changes. These effects were sensitive to changes in level of disease (JD and NCD) on the farm, and the costs and effects of making changes. The NPV of making any on-farm change when JD was not present on the farm was negative. Overall, FF implementation yielded positive net benefits of $426,351 or $749,808, depending on whether a veterinarian or non-veterinarian served as the facilitator. The NPV was most sensitive to changes in burden of disease, the cost of implementing changes, and the proportion of FF participants that had JD and NCD on the farm. Benefits of FF implementation are also likely to accrue to veterinarians, as a result of professional facilitator training, and the Ontario dairy industry, as a by-product of improved milk quality and safety; therefore, the true net benefits of FF implementation are likely underestimated. Overall, the FF process should be considered an economically viable program and worthy of investment as part of a JD control strategy, as it demonstrates potential to yield positive net benefits for the Ontario dairy industry.

Control of paratuberculosis: who, why and how. A review of 48 countries.

Paratuberculosis, a chronic disease affecting ruminant livestock, is caused by Mycobacterium avium subsp. paratuberculosis (MAP). It has direct and indirect economic costs, impacts animal welfare and arouses public health concerns. In a survey of 48 countries we found paratuberculosis to be very common in livestock. In about half the countries more than 20% of herds and flocks were infected with MAP. Most countries had large ruminant populations (millions), several types of farmed ruminants, multiple husbandry systems and tens of thousands of individual farms, creating challenges for disease control. In addition, numerous species of free-living wildlife were infected. Paratuberculosis was notifiable in most countries, but formal control programs were present in only 22 countries. Generally, these were the more highly developed countries with advanced veterinary services. Of the countries without a formal control program for paratuberculosis, 76% were in South and Central America, Asia and Africa while 20% were in Europe. Control programs were justified most commonly on animal health grounds, but protecting market access and public health were other factors. Prevalence reduction was the major objective in most countries, but Norway and Sweden aimed to eradicate the disease, so surveillance and response were their major objectives. Government funding was involved in about two thirds of countries, but operations tended to be funded by farmers and their organizations and not by government alone. The majority of countries (60%) had voluntary control programs. Generally, programs were supported by incentives for joining, financial compensation and/or penalties for non-participation. Performance indicators, structure, leadership, practices and tools used in control programs are also presented. Securing funding for long-term control activities was a widespread problem. Control programs were reported to be successful in 16 (73%) of the 22 countries. Recommendations are made for future control programs, including a primary goal of establishing an international code for paratuberculosis, leading to universal acknowledgment of the principles and methods of control in relation to endemic and transboundary disease. An holistic approach across all ruminant livestock industries and long-term commitment is required for control of paratuberculosis.

An agent-based model evaluation of economic control strategies for paratuberculosis in a dairy herd.

This paper uses an agent-based simulation model to estimate the costs associated with Mycobacterium avium ssp. paratuberculosis (MAP), or Johne's disease, in a milking herd, and to determine the net benefits of implementing various control strategies. The net present value (NPV) of a 1,000-cow milking herd is calculated over 20 yr, parametrized to a representative US commercial herd. The revenues of the herd are generated from sales of milk and culled animals. The costs include all variable and fixed costs necessary to operate a representative 1,000-cow milking herd. We estimate the NPV of the herd with no MAP infection, under an expected endemic infection distribution with no controls, and under an expected endemic infection distribution with various controls. The initial number of cows in a herd with an endemic MAP infection is distributed as 75% susceptible, 13% latent, 9% low MAP shedding, and 3% high MAP shedding. Control strategies include testing using ELISA and fecal culture tests and culling of cows that test positive, and culling based on observable milk production decrease. Results show that culling cows based on test results does not increase the herd's NPV and in most cases decreases NPV due to test costs as well as false positives and negatives with their associated costs (e.g., culling healthy cows and keeping infected cows). Culling consistently low producing cows when MAP is believed to be present in the herd produces higher NPV over the strategy of testing and culling MAP infected animals, and over the case of no MAP control.

The effect of paratuberculosis on milk yield--A systematic review and meta-analysis.

Bovine paratuberculosis is a disease characterized by chronic granulomatous enteritis causing protein-losing enteropathy. Adverse effects on animal productivity are key drivers in the attempt to control paratuberculosis at the farm level. Economic models require an accurate estimation of the production effects associated with paratuberculosis. The aim of this study was to conduct a systematic review and meta-analysis to investigate the effect of paratuberculosis on milk production. A total of 20 effect estimates from 15 studies were included in the final meta-analysis. Substantial between-study heterogeneity was observed. Subgroup analysis by case definition and study design was carried out to investigate heterogeneity. The majority of between-study variation was attributed to studies that defined cases on serology. Calculation of a pooled effect estimate was only appropriate for studies that defined cases by organism detection. A reduction in milk yield, corrected for lactation number and herd of origin of 1.87 kg/d, equivalent to 5.9% of yield, was associated with fecal culture or PCR positivity in individual cows.

Agent-based model for Johne's disease dynamics in a dairy herd.

Johne's disease is an infectious gastrointestinal disease in ruminants caused by Mycobacterium avium subsp. paratuberculosis that causes diarrhea, emaciation, decreased milk production and eventually death. The disease is transmitted in utero and via milk and colostrums to calves, and fecal-orally to all age classes. Financial losses due to the disease are estimated to be over $200 million in the US dairy industry. The goal of this study was to evaluate the cost effectiveness of control measures based on diagnosis with a sensitive ELISA, EVELISA. An agent-based, discrete time model was developed to simulate Johne's disease dynamics in a US dairy herd. Spatial aspects of disease transmission were taken into account by using six spatial compartments. The effects on disease prevalence were studied with and without transmission routes included in the model. Further, using the model, cost effectiveness of ELISA-based Johne's disease control was evaluated. Using the parameters we collected and assumed, our model showed the initial prevalence of Johne's disease (33.1 ± 0.2%) in the farm increased to 87.7 ± 1.7% in a 10 year-simulation. When ELISA-based control measures were included in the simulation, the increase in prevalence was significantly slowed down, especially when EVELISA was used. However, the level of the prevalence was still higher than the initial level after 10 year simulation even with the ELISA-based diagnostic intervention. The prevalence was further reduced when quarterly ELISA testing was included. The cost analysis showed that the quarterly ELISA and EVELISA testing could bring $44.8 and $51.5/animal/year more revenues, respectively, to a dairy farm.

The association of detection method, season, and lactation stage on identification of fecal shedding in Mycobacterium avium ssp. paratuberculosis infectious dairy cows.

Mycobacterium avium ssp. paratuberculosis (MAP) is the causative organism of Johne's disease. Although fecal culture is considered the standard diagnostic test, the long incubation times, costs, and intermittent shedding of MAP hinder efficient screening programs based on culture results. The primary objectives of this study were to determine the detection ability of solid culture, broth culture, and real-time PCR (qPCR) for MAP in fecal samples and to assess how shedding patterns of MAP in feces vary with lactation stage and season. This knowledge could improve the use of these diagnostic assays in Johne's management programs. For this study, 51 MAP-infectious cows from 7 Atlantic Canadian dairy farms had fecal samples collected monthly over a 12-mo period. Samples were analyzed for MAP bacterial load via solid culture, broth culture, and qPCR. For all fecal samples, 46% [95% confidence interval (CI): 40 to 51%] were positive by solid culture, 55% (95% CI: 50 to 60%) by broth culture, and 78% (95% CI: 73 to 82%) by qPCR. Sensitivity of qPCR was numerically higher in the dry and postpartum lactation periods, and qPCR detection in summer and fall was 85% of that in winter and spring. Furthermore, culture-determined moderate or light shedding categories generally corresponded to qPCR cycle threshold values <35, but heavy shedding categories corresponded to qPCR values <29. Direct fecal qPCR is a MAP detection method that is quick and less costly than culture techniques, and it avoids the use of decontamination steps that could decrease numbers of bacteria in a sample below the detection limit. This study indicates that, for known MAP-positive cows, fecal qPCR had high sensitivity of MAP detection, thereby supporting the use of direct fecal qPCR as part of a Johne's herd control program.

Invited review: The economic impact and control of paratuberculosis in cattle.

Paratuberculosis (also called Johne's disease) is a chronic disease caused by Mycobacterium avium ssp. paratuberculosis (MAP) that affects ruminants and other animals. The epidemiology of paratuberculosis is complex and the clinical manifestations and economic impact of the disease in cattle can be variable depending on factors such as herd management, age, infection dose, and disease prevalence, among others. Additionally, considerable challenges are faced in the control of paratuberculosis in cattle, such as the lack of accurate and reliable diagnostic tests. Nevertheless, efforts are directed toward the control of this disease because it can cause substantial economic losses to the cattle industry mainly due to increased premature culling, replacement costs, decreased milk yield, reduced feed conversion efficiency, fertility problems, reduced slaughter values, and increased susceptibility to other diseases or conditions. The variability and uncertainty surrounding the estimations of paratuberculosis prevalence and impact influence the design, implementation, and efficiency of control programs in diverse areas of the world. This review covers important aspects of the economic impact and control of paratuberculosis, including challenges related to disease detection, estimations of the prevalence and economic effects of the disease, and the implementation of control programs. The control of paratuberculosis can improve animal health and welfare, increase productivity, reduce potential market problems, and increase overall business profitability. The benefits that can derive from the control of paratuberculosis need to be communicated to all industry stakeholders to promote the implementation of control programs. Moreover, if the suspected link between Johne's disease in ruminants and Crohn's disease in humans was established, significant economic losses could be expected, particularly for the dairy industry, making the control of this disease a priority across dairy industries internationally.

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.

Economic evaluation of participation in a voluntary Johne's disease prevention and control program from a farmer's perspective--The Alberta Johne's Disease Initiative.

The Alberta Johne's Disease Initiative (AJDI) is a Johne's disease (JD) control program with the goal of reducing the spread of Mycobacterium avium ssp. paratuberculosis (MAP) through implementation of best management practices. The objective was to estimate the economic benefit of participation in the AJDI. A decision tree was constructed in which disease prevalence, test characteristics, and probabilities for implementation of best management practices suggested by herd veterinarians were implemented. Analysis was performed using a Markov analysis, and input data were assigned using estimates from the AJDI and published data. A cost-effectiveness analysis was performed and the net benefit of participation (from the perspective of a dairy farmer) in the AJDI compared with no participation was calculated. A series of 1-way sensitivity analyses were used to control for uncertainty. Farms participating in the AJDI were estimated to have a net benefit of Can$74 per cow over the course of 10 yr. If project costs were covered by the participating farm, the net benefit was Can$27. In addition to the effects on MAP infection, a reduction in calf diarrhea was modeled for farms that improved their calf management through the use of pasteurizers. In that case, the additional costs outweighed additional revenues compared with the baseline analysis, resulting in a reduced net benefit of Can$19. Participation would not be cost effective if cows in early stages of MAP infection did not have decreased production and if prevalence of MAP infection did not increase on farms with poor management. A limitation of the study, despite high uncertainty in some input parameters, was the lack of knowledge regarding changes in prevalence on farms with various management strategies. In conclusion, participation in the AJDI was cost effective for the average Alberta dairy farm.

Mycobacterium avium subspecies paratuberculosis: an insidious problem for the ruminant industry.

Mycobacterium avium subspecies paratuberculosis is considered as one of the most serious problems affecting the world's ruminant industry due to its significant impact on the global economy and the controversial issue that it may be pathogenic for humans. M. avium subspecies paratuberculosis is the causative agent of Johne's disease in animals and might be implicated in cases of human Crohn's disease. We provide an insight into M. avium subspecies paratuberculosis from some bacteriological, clinical, and molecular epidemiological perspectives.

Slaughterhouse prevalence of ovine paratuberculosis in Southern India.

Ovine paratuberculosis is a threat to small animal holders in terms of economic loss such as reduced growth performance and early culling. In order to study the slaughterhouse prevalence of ovine paratuberculosis, the slaughterhouse sheep samples (which are poor in body condition) collected over a period of two and half years from 1,034 suspected male sheep (poor in body condition) and 40 normal sheep (good body condition and subsequently negative by all the diagnostic tests employed) aged between 16 and 18 months were slaughtered at various abattoirs of Tamil Nadu. All the sheep taken in this study were maintained in almost same management conditions. DNA was extracted from 1,034 intestinal tissue and mesenteric lymph node and 121 were positive by IS 900 PCR. One hundred ten and 56 were positive by absorbed ELISA and Ziehl-Neelsen staining, respectively. In histopathology, 28 animals showed gross lesions of paratuberculosis infection (20-multibacillary and 8-paucibacillary forms). Out of 1,034 sheep tissues cultured, 32 showed cultural growth in Middlebrook 7H9 and 26 in Herrold's egg yolk medium. None of the 40 normal sheep were positive by any of the tests employed. In general, the mean body weight of paratuberculosis-affected animal either by any one of the tests employed was less than the non-affected sheep. The approximate economic loss per sheep/farmer/year is around Rs 1,840 (US$ 38.33) in paratuberculosis-affected sheep.

Producer survey of bird-livestock interactions in commercial dairies.

The objective of this producer survey was to identify and estimate damage caused by bird-livestock interactions in commercial dairies. The interactions between birds and livestock have previously been implicated in causing economic damage while contributing to the environmental dissemination of microorganisms pathogenic to livestock and humans. Very little research exists to help producers understand what bird species use dairies, why they use dairies, or the scope and nature of damage created as a result of bird-livestock interactions. To better characterize these interactions, we surveyed dairy operators within Pennsylvania, New York, and Wisconsin. Survey results suggest that the most common and destructive bird species found on commercial dairies are invasive to North America, and their use of dairies is associated with the loss of cattle feed, increased operating costs, and an increase in dairies self-reporting Salmonella spp. and Mycobacterium avium ssp. paratuberculosis. Cattle feed loss estimates generated from this survey were used to parameterize an input-output (IO) economic model using data from 10 counties in the state of Pennsylvania (Bedford, Berks, Blair, Bradford, Chester, Cumberland, Franklin, Lancaster, Lebanon, and Somerset). This IO model allowed us to estimate direct, indirect, and induced economic effects of feed loss from bird damage to dairies within these counties. The IO model output suggests that feed loss costs Pennsylvania between $4.11 and $12.08 million (mean $10.6 million) in total economic damage, with approximately 43 to 128 jobs (mean 112) forgone statewide in 2009.

Examples and suggestions for the control of paratuberculosis in European cattle.

Paratuberculosis, or Johne's disease (JD), is caused by Mycobacterium avium subspecies paratuberculosis (MAP), is found in ruminants worldwide and can cause considerable economic losses in cattle. Control efforts and programs for JD in cattle are very diverse among European states, in Austria clinical JD is rated as a notifiable disease since 2006. The voluntary control programs established in many European countries, show different aims, measurements and acceptance. Most control programs for JD are based on a test and cull strategy, combined with hygienic precautions. Unfortunately, the willingness to participate in such programs by farmers and veterinarians is limited due to high costs, intensive workload, long duration and limited success. To overcome this drawback and to harmonize the control of MAP in Europe, a basic program with defined minimum standards is suggested. This "minimal program" for the control of JD in cattle consists of 3 steps. Step 1 includes diagnostic evaluation of every case of diarrhea in adult cattle and culling of animals with clinical JD. Step 2 is the implementation of basic management measures, adapted to the potentials of the individual farm. Step 3 consists of regularly evaluation of the MAP-herd status with the focus on MAP-shedding animals. This basic control program can be performed with reasonable costs and work load in most cattle herds and might serve as an international minimum standard for MAP-control in cattle. Such a program can also pose an incentive to decrease MAP-infections for those not willing to participate in more sophisticated control programs.

Prevalence and prevention of paratuberculosis in North America.

The United States of America (U.S.) has made several attempts over the years to develop a producer accepted voluntary program. The focus of the U.S. Voluntary Bovine Johne's Disease Control Program (VBJDCP) is to provide producers with the tools to control Johne's disease on their farms and identify herds with a low risk for the presence of Mycobacterium avium subspecies paratuberculosis (MAP) infection. The VBJDCP includes an evaluation of producers' operations to identify practices that could allow the transmission of MAP among animals or between premises. Once risky practices havebeen identified, a herd management plan is developed to assist the producer in correcting risky practices. In addition to management changes, vaccination is a control tool allowed in the U.S. because it reduces the clinical signs of Johne's disease and the shedding of MAP. Testing is used in addition to management changes. While the classification component of the VBJDCP dictates the amount and type of testing herd owners are required to conduct, the education and management components of the VBJDCP does not specify testing protocols. The testing for control is intended to fit the needs and resources of producers and can be quite flexible. Management changes on the farm remain the key to control and programs cannot replace well thought out plans by producers that are specific to their resources, facilities, and operation.

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.

Effect of paratuberculosis on slaughter weight and slaughter value of dairy cows.

The effect of infection with Mycobacterium avium ssp. paratuberculosis (MAP) on slaughter weight and slaughter value of dairy cows was evaluated. Two data sets were analyzed: 1) recordings from 1,031 cows from herds in a pilot study to control MAP infections, and 2) recordings from 36,455 cows from herds participating in the Danish MAP control program. The effect of stage of MAP infection on carcass weight and slaughter value was assessed by ANOVA. Infection stage was diagnosed by repeated milk antibody ELISA in both data sets. Furthermore, repeated fecal culture was recorded in data set 1 and occurrence of enteritis or enteric edema found at slaughter was recorded in data sets 1 and 2. Compared with presumably unaffected cows with at least 2 ELISA negative tests, slaughter weight and value were reduced by 10 and 17%, respectively, in cows with positive ELISA at slaughter. If the cow was also positive using fecal culture, slaughter weight and value were reduced up to 15 and 31%, respectively. The slaughter weight and value were reduced an additional 20 and 31%, respectively, for cases with recorded enteritis or edema. Thereby, summarized weight losses of up to 31% and slaughter value losses up to 48% occurred. Cows with negative fecal cultures had reduced slaughter results only if they were ELISA-positive in the last 2 tests. Losses of both slaughter weight and slaughter value caused by MAP were more severe than previously estimated. These losses could be predicted by repeated milk ELISA tests with or without confirmation with fecal culture.

A longitudinal study on the impact of Johne's disease status on milk production in individual cows.

Longitudinal data from 3 commercial dairy herds in the northeast United States were collected from 2004 to 2007. Johne's disease status, as indicated by Mycobacterium avium ssp. paratuberculosis infection levels, was determined through quarterly ELISA serum testing, biannual fecal culture, and culture of tissues at slaughter. Milk production data were collected from the Dairy Herd Improvement Association. The effect of Johne's disease status on milk production was analyzed using a mixed linear model with an autocorrelation random effect structure. Infected animals produced more milk than uninfected cows before they began shedding M. avium ssp. paratuberculosis. Cows infected with M. avium ssp. paratuberculosis had monthly decreases of 0.05 to 1 kg in daily milk production relative to uninfected animals, with greater decreases in progressive disease categories. Animals with fecal culture results of >30 cfu/g produced approximately 4 kg less milk per day compared with uninfected cows. These results will be valuable in calculating the economic effect of Johne's disease.

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.

[Two-stage control of paratuberculosis: Herd-status surveillance as the basis for operational measures to reduce the prevalence. - Experiences from Lower Saxony, Hesse, Thuringia and Tyrol]. / Zweistufige Paratuberkulosebekämpfung in der Praxis: Überwachung auf Herdenebene als Basis für betriebliche Maßnahmen zur Prävalenzsenkung.

Economic losses caused by paratuberculosis (Johne's disease) can be high in infected herds. A universally accepted concept for the surveillance or control of paratuberculosis in cattle herds has not yet been established.In the course of the program for the reduction of MAP (Mycobacterium avium subsp. paratuberculosis) infections in Lower Saxony, Germany, dairy farms are obliged to test bulk tank milk samples for the presence of MAP-antibodies every 6 months. In case of a non-negative result, testing is required at the single animal level. Farmers can than decide whether they join a program to control MAP-infections in their herd. Within the voluntary certification program for paratuberculosis in Hesse, Germany, the MAP-herd status is evaluated using boot swab sampling. On positive farms, animals are tested at 6-month intervals by milk or blood serology with timely culling of positive individuals. The program for the abatement of paratuberculosis in cattle herds in Thuringia, Germany, is based on a yearly fecal examination for MAP-shedding of all adult cattle within a herd. Fecal MAP-positive animals should be culled as soon as possible. The basis of the surveillance and control program for MAP in Tyrol, Austria, is the biennial survey of the MAP-herd status by boot swab sampling. Farms with a MAP-positive boot swab result have the option to have their adult animals tested for MAP by single animal fecal sampling. On the basis of the results of these samples, farmers can decide whether they wish to join the MAP-control program.The programs presented above show that a two-stage approach consisting of the evaluation of the MAP-herd level, followed by the testing of single animals, represents a feasible approach for the surveillance and control of paratuberculosis in cattle herds.

Scenario analysis of changes in consumption of dairy products caused by a hypothetical causal link between Mycobacterium avium subspecies paratuberculosis and Crohn's disease.

Johne's disease is an infectious disease of cattle caused by Mycobacterium avium subspecies paratuberculosis (MAP). Crohn's disease (CD) is a human disease of unknown etiology that is characterized by chronic bowel inflammation. No causal link has been scientifically established between MAP and CD, but it is important to understand possible impacts on society should such a causal link be established. The goal of this paper is to analyze the implications and the possible economic impacts that finding such a link would have on milk demand in the dairy industry and to provide a framework for further discussion among stakeholders. Three scenarios were developed based on the effectiveness of possible risk-mitigation strategies. In the first scenario, it was assumed that an effective strategy exists; therefore, a negligible demand decrease in the consumption of dairy products was expected. In the second scenario, it was assumed that new risk mitigation would need to be implemented to minimize the health hazard for humans. In this case, a small milk demand decrease was expected, but larger demand decreases were also possible. The third scenario assumed that no fully effective risk mitigation was available, and this resulted in a considerable demand decrease and a potential reduction in milk supply as a result of regulatory measures. A milk demand reduction of 1 or 5% resulted in a reduction in consumer surplus of $600 million and $2.9 billion, and a reduction in dairy farm income of $270 million and $1.3 billion, respectively. A decrease in milk supply would cause a slight increase in total losses, but would cause the greatest losses to test-positive dairy farms. Given the current scientific knowledge about MAP and CD, we conclude that if a link were established, it is most likely that the first or second scenario would occur. Thus, consumer response and economic consequences to the discovery of such a link are expected to be limited, but could be large if the consumer's perception of risk is large or if risk-mitigation strategies were ineffective.