NEWS

This research publication is noteworthy because of the paucity of reports on Johne's disease in Egypt.  It also is one of the few recent papers to report clinical hematology and chemistry studies in conjunction with diagnostics for Johne's disease.

This study diagnosed Johne's disease in dairy cattle by ELISA.  17 cows were ELISA-positive and had persistent diarrhea.  45 cows were ELISA-positive but clinically normal.  138 cows were ELISA-negative and clinically normal; 15 of these cows were used as controls.  Clinical hematology and chemistry parameters were compared for these 3 groups of cattle.  The study found significantly lower RBCs (red blood cell numbers), PCV (packed cell volume), total serum protein, serum globulin and serum glucose.  No significant differences in oxidative stress markers were found for the 17 clinically affected cows.

Typical colonies of MAP (IS900 PCR-confirmed) were isolated from the fecal samples of clinically affected cows.  Phylogenetic analysis of these isolates revealed high similarities with MAP strains from both India and Egypt.  This study highlights that MAP infections affect dairy farms in Egypt.

This publication by Ahmed Abdelaal et al., appears in the Solvenian Veterinary Research Journal volume 56 (Suppl 22): 421–431, 2019.  This is an Open Access journal.  As their policy states: This journal provides immediate open access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge.

A review of the epidemiology of paratuberculosis was published in two parts by Dr. Conor McAloon et al. in the April 2019 issue of The Veterinary Journal.  Unfortunately the articles are not Open Access, meaning you must pay a fee to gain access to the full article unless your institution subscribes to the journal.

Dr. McAloon works in the Section of Herd Health and Animal Husbandry, School of Veterinary Medicine, University College Dublin, Ireland.  He recently received his PhD and is one of the promising new young scientists in the field of paratuberculosis research.  The reviews come from his thesis and are published in two parts: Part 1 concerns broader aspects of epidemiology of paratuberculosis, and Part 2 concerns on-farm control of paratuberculosis.  Both are excellent and provide the most comprehensive and current information on the subject.

Epidemiology is a topic under each of the main animal species covered on this website.  For example this link takes you to the epidemiology of Johne's disease in dairy cattle: Dairy cattle/Epidemiology

The establishment of the Irish Johne’s Control Programme (IJCP) has been led by AHI in conjunction with industry stakeholders. Following a previous pilot programme, Phase One of the IJCP was launched in late 2017 as a voluntary national programme for the dairy sector. The (IJCP) is a long term programme for the control of Johne’s disease and recognises the value of effective and on-going disease prevention and containment practices to control the infection. The IJCP provides pathways for test-negative and test-positive herds to demonstrate progress towards an improved herd assurance for Johne’s disease, while also improving calf health and biosecurity and providing market assurance.

Further details of the IJCP are available at www.animalhealthireland.ie. Phase Two of the IJCP began in January 2019, with the ambition of achieving a significant level of engagement with dairy herds in the near future. Due to retirement, a vacancy has arisen for a programme manager to oversee the continued development of the IJCP. Reporting directly to the CEO, the successful candidate will have responsibility for all aspects of the IJCP, building on the significant progress made to date.

Link to full position announcement: Johne's Disease Programme Manager-Animal Health Ireland-2019

RESEARCH ARTICLE

Veterinary researchers in Ontario Canada worked to answer this question and published their findings in the Journal of Dairy Science (online 07-MAR-2019).

ABSTRACT: Motivating uptake of management change recommendations requires knowledge of the barriers and motivators influencing producer behavior. This study investigated dairy producers' and veterinarians' perceptions of the barriers and motivators influencing the adoption of Johne's disease (JD) control recommendations in Ontario, Canada. Eight focus groups, 6 with dairy producers and 2 with veterinarians, were conducted and thematically analyzed. Both producer and veterinarian groups identified physical resources (i.e., time, money, infrastructure) and producer mindset (i.e., perceived priority of JD, perceived practicality of JD control recommendations) as key barriers to adoption. Producers tended to prioritize JD control on their farm based on their lived experiences with JD and their view of the public's concern about JD. Many agreed that JD recommendations should focus on biosecurity more holistically and emphasize the broader health benefits of limiting calf exposure to many fecal–orally transmitted diseases. Producers also highlighted that some recommendations for on-farm change (i.e., keeping a closed herd, buying from low-risk herds) were unrealistic or too difficult to perform and often disrupted their habits or routine. In contrast, veterinarians suggested that most recommendations were practical and are routinely recommended. Participants suggested both extrinsic (i.e., incentives, premiums, penalties and regulations, and extension and communication) and intrinsic (i.e., pride and responsibility) methods for motivating producers. This study highlights the importance of producer mindset in on-farm change and offers insights into the attitudes and perceived barriers influencing on-farm change.

COMMENT: When dairy producers are asked to shoulder 100% of the costs of a JD control program and receive no compensation for their time and effort or for the costs of making management changes and herd testing, producer adoption of JD control programs will likely remain very low.  If dairy processors would incentivize dairy producers by paying more for milk from test-negative herds, the raw milk supply would eventually harbor fewer MAP and consumers would be better protected from MAP in dairy products.  It’s that simple: Money motivates.

Research Article

PREFACE:

Should I cull the off-spring of an ELISA-positive cow?

This is one of the more common questions asked of veterinarians regarding Johne's disease control programs.  Today's news item is about research done in the UK targeted specifically at this question for dairy cattle.

ABSTRACT: A longitudinal study was carried out following a cohort of 440 UK dairy cows in 6 herds recruited in 2012-2013. Individuals entering the milking herd were routinely monitored for the presence of MAP using quarterly milk ELISA testing.  The relationship between time until first detection of infection and dam MAP status was investigated.  Dam test status for MAP was found to be the only observed factor that was significantly associated with time to an individual testing MAP-positive (p = 0.012). When compared to test-negative dams, these UK scientists found a marginally significant effect of having a positive dam at time of calving, that increased the hazard of an individual testing positive by a factor of 2.6 (95% confidence interval: 0.89–7.79, p = 0.081). Further positive associations were found with dams becoming positive after the birth of the subject; a dam seroconverting within 12 months post parturition being associated with a 3.6 fold increase in hazard (95% confidence interval: 1.32–9.77, p = 0.013), and dams seroconverting more than a year after calving increased the hazard by a factor of 2.8 (95% confidence interval: 1.39–5.76, p = 0.004). These results suggest that cows may be transmitting MAP to their offspring at an earlier stage than had previously been thought, and so raise important questions about how this transmission may be occurring. The results of the study may have important practical implications for the management on-farm of the offspring of MAP-positive animals, with the potential to vastly reduce the time required to eliminate this chronic disease.

This link takes you to the full article, however, it is not Open Access.

CONCLUSION: The answer to the off-spring culling question for commercial diary herds is yes (in most instances).  It is better to retain as herd replacements only those animals born to tested-negative dams and dams that remain test-negative.  Of course, each dairy is unique and for animals with high genetic merit alternatives to culling might be considered.  These findings are most relevant to dairy cattle herd controlling Johne's disease by testing cattle using the milk ELISA and animal husbandry conditions in the common in the UK.

Scientific Review Article

Scientists in Spain have published a novel and comprehensive comparison of diseases that are considered "chronic regional intestinal inflammatory diseases" (CRIID), with paratuberculosis being a prototype.  This review contrasts the nature of pathology seen in humans, nonhuman primates and 13 other animal species or types of animals with excellent color photomicrographs illustrating the pathology seen with MAP infections in cattle.  It also tabulates the history of these diseases from 1502 to the present, the epidemiology of CRIID and affect of therapeutics.  The review lists 151 references.

Although written for the technical specialist, especially pathologists, it is an excellent concise review of the subject that may help lead to a more informed discussion on the role of MAP in many forms of inflammatory bowel conditions.  This article was published in the  journal Comparative Immunology, Microbiology and Infectious Diseases (volume 62, pages 88-100, February, 2019).

Note: It is well known that all ruminants are susceptible to MAP infection.  Our website has a special page for teh NON-ruminants that have been shown to be MAP-infected.  Check it out here!

Risk assessments are the foundation of Johne’s control programs. They assist herd owners develop management plans to minimize risks for MAP introduction and spread in their herd. The risk assessment and management plan (RAMP), prioritize management changes to insure herd owners focus on making changes in herd management that maximize efforts to control Johne’s disease.

The University of Wisconsin School of Veterinary Medicine has converted the traditional paper RAMP designed for us in the U.S. into an App that speeds the process, makes it paperless, and even allows for submission of the complete RAMP to both the animal owner and the state official charged with monitoring Johne’s control programs directly from the App. The RAMP App is designed for both dairy and beef herds, but owners of other animals can use the same principles for their herd or flock.

The Johne’s RAMP App is one of 15 such Apps for iPads developed by the Production Medicine unit of the UW School of Veterinary Medicine for dairy herd health monitoring. Click here to see the full list.

More about RAMPs for dairy herds can be found at this link.

More about RAMPS for beef herd can be found at this link.

This is a direct link to the iTunes App store to obtain the JD Risk Assessor.

Program status report

The UK has developed a commercially driven framework for the control of Johne’s disease in dairy herds. The program started in 2010 with a prolonged education program to secure farmer and veterinarian engagement and has now in the second year of an exciting phase where farmers and vets work together to develop a written agreed plan of action to manage JD effectively.

The program is managed by the Action Group on Johne’s , which brings together all relevant industry organizations that have an interest in managing Johne’s, including vets, labs, farmers’ unions and milk processors.

6 control strategies have been defined by the group and over 1,153 veterinarians have completed online training and certification allowing them to deliver the program.

Each farmer must work with their accredited Johne’s vet to conduct a risk assessment, undertake surveillance to assess the status of the herd and define an agreed control plan from one of the six strategies available.

The farmer pays for any testing and consultancy advice, the milk processor encourages or in some cases insists on compliance and the vet works with the farmer to reduce the incidence of disease and signs a certificate of compliance which is returned to the processor for collation. There is no subsidy for testing or veterinary work.

20 milk processors are members of the NJMP representing 64% of Great Britain’s milk supply. 16 processors have achieved 90% compliance and 10 have achieved 100% compliance. 56% of the UK milk supply are effectively assured by the framework. It is estimated a further 20% of UK farmers have a robust plan in place however their processor may not choose to be a member of the program.

For more details of the program visit Action Johne’s.

Research Article

Scientists at the University College Dublin, in partnership with noted Australian epidemiologist, Evan Sargeant, and Animal Health Ireland, evaluated multiple diagnostic testing strategies for Irish dairy herds. The aim of their study was to evaluate the suitability of a range of national surveillance methods, both for case detection and for providing confidence of herd freedom from MAP infection, in terms of herd sensitivity, positive and negative predictive values, overall cost, and utility, including any logistical factors associated with their use.

Strategies the scientific team evaluated included:

• ELISA on individual milk samples from all lactating cows in a herd annually.
• ELISA on serum samples from all adult cows in a herd annually.
• ELISA on serum samples collected at slaughter from culled cows (serum already being collected for the Irish brucellosis program); with estimates made for testing 50%, 75% or 100% of culled cows.
• ELISA on bulk tank milk.
• PCR on 6 environmental fecal samples.
• PCR on pooled fecal samples (5/pool) for all adult cows.

In general, testing for the MAP organism by PCR on pooled fecal samples from all adult cows performed best, when cost was not a consideration. MAP detection at the herd-level using environmental fecal sample collection provided the best combination of herd testing accuracy and affordability.

This is consistent with findings in the U.S. where environmental fecal samples are a component of the Voluntary Bovine Johne’s Disease Control Program. Environmental fecal testing was also the basis of the last (2007) survey of U.S. dairy herds as reported by Lombard et al. (Preventive Veterinary Medicine 108:234-238, 2013.)

Readers are strongly encouraged to read the full Open Access report in the Journal of Dairy Science (volume 102, pages 1-14) to appreciate the many nuances of the findings of this excellent study.

Researchers in Iran published a novel study comparing the rates of MAP detection by IS900 PCR, the nature of the intestinal pathology, and the ability to detect MAP by acid-fast staining among 30 humans with Crohn's disease (CD), 30 humans with non-inflammatory bowel disease (nIBD), 30 goats with clinical signs compatible with Johne's disease (JD) and 30 healthy goat kids. For the human subjects, they reported that 47% of CD patients and 13% of nIBD controls were IS900 PCR-positive for MAP. By contrast, 70% of JD goats and 0% of healthy goats were IS900 PCR-positive. Acid-fast bacteria (AFB) were seen in tissues of 7% of CD cases. In these cases the number of  AFB was characterized as paucibacillary, meaning very few red-staining bacteria were seen. Excellent photomicrographs are provided in the publication. By contrast AFB were seen in 0% nIBD controls, 90% of goat JD cases and 0% of healthy goat controls.

Special to this publication is a table contrasting the types of pathology seen in CD and JD. Pathology common to both the CD patients and JD goats, respectively was: lymphangiectasia/edema (67% vs 96%), vasculitis/lymphangitis (20% vs 73%), diffuse granulomatous enteritis (20% vs 33%), focal or multifocal granulomatous enteritis (63% vs 14%), neuritis or neuronal hyperplasia (36% vs 43%) and cryptitis (40% vs 14%). Pathology unique to JD goats (seen in 0% of CD patients) was: Diffuse multibacillary (abundant AFB) granulomatous enteritis (see in 43% of goats). Pathology unique to CD patients (seen in 0% of goats) was: Ulceration (73%), fibrosis (30%), pyloric gland metaplasia (40%), thrombosis (30%), paneth cell metaplasia/hyperplasia (17%) and goblet cell hyperplasia (14%).

Comment: Readers interested in comparative pathology of CD and JD will appreciate the discussion section of this publication. When considering pathology comparisons between CD and JD, readers should remember: 1) that CD patients generally have undergone prolonged therapy with a wide array of immunosuppressive drugs which may affect the nature of the pathology, while animals are not so treated, and 2) that zoonotic infections seldom cause identical pathology in the animal and human hosts. The duration on therapy for CD patients in this study was not reported but the mean age was 34 years so one could surmise that the patients had their disease for some time before the pathological assessment.

The full Open Access article is available: F. Zarei-Kordshouli, B Geramizadeh, and A. Khodakaram-Tafti. 2019. Prevalence of Mycobacterium avium subspecies paratuberculosis IS 900 DNA in biopsy tissues from patients with Crohn’s disease: histopathological and molecular comparison with Johne’s disease in Fars province of Iran. BMC Infectious DIseases 19:23. doi.org/10.1186/s12879-018-3619-2