Johne’s Disease (JD) is a common disease in the dairy industry caused by the bacteria Mycobacterium avium subspecies paratuberculosis, causing diarrhea, weight loss and subcutaneous edema in cows, allowing for a more accurate diagnosis based on clinical signs. Clinical signs in small ruminants are more nonspecific and frequently the only sign is weight loss (Pugh, 2002), which can be difficult to differentiate from other common ailments such as parasite infections. While studies from other countries indicate that JD is a widespread problem with a significant economic impact, there is no prevalence data for small ruminants in the US (Collins, 2011). This project seeks to conduct JD surveillance and determine prevalence in goat herds in Northern New York. The project will use blood ELISA testing, fecal culture and PCR test results as data points and utilize the New York State Sheep and Goat Health Assurance Program (NYSSGHAP) to aid with on farm data collection and one on one farmer outreach and education. This project allows us to better characterize prevalence of disease in the region using Bayesian Statistical Modeling. Outreach for this project will include presentations across the state by NYS Department of Agriculture and Markets field veterinarians at continuing education events along with discussion at other NYSSGHAP meetings with individual producers. Cornell Cooperative Extension livestock educators will be able to present the results at sheep and goat meetings directed at producers, one of which will be recorded and posted online for wider distribution.
This project seeks to conduct Johne’s disease surveillance and determine prevalence in goat herds in Northern New York. This project would allow further study of JD present in the area, allowing farmers to have a better understanding of the disease in goat herds. The project will use blood ELISA testing, fecal culture and PCR test results as data to extrapolate from. Based on phase one of the project focusing on JD in sheep, we have shown that JD is widespread in the region. This will allow us to better characterize prevalence of disease in the region using Bayesian Statistical Modeling. This statistical method allows us to factor in the three different tests and their respective specificities and sensitivities to determine a more accurate prevalence for the region. The benefit to farmers will be to heighten awareness of the presence of infection in the region, and to gain assistance with management and biosecurity relating to JD. As for farmers not in the locale, this project will not only further characterize the prevalence of JD in the Northeast; but in the US since no other studies have been done pertaining to prevalence of JD in small ruminants here.
Johne’s Disease (JD) is a common disease in the dairy industry caused by the bacteria Mycobacterium avium subspecies paratuberculosis, causing diarrhea, weight loss and subcutaneous edema in cows, allowing for a more accurate diagnosis based on clinical signs. Clinical signs in small ruminants are more nonspecific and frequently the only sign is weight loss (Pugh, 2002), which can be difficult to differentiate from other common ailments such as parasite infections. While there is significant research on JD in bovines, research into the prevalence and significance of this disease in ovines and caprines is minimal. Estimations of prevalence of JD in the sheep and goat population of Ontario, Canada in 2010 estimated that 86% of dairy goat herds and 66% of dairy sheep flocks have animals infected (Bauman, et al, 2016). Similarly, Cyprus showed a prevalence of almost 50% of goat herds and 61% of sheep flocks to be infected (Liapi, et. al., 2013). These numbers are similar to the 70% of herds estimated with JD in the dairy industry in the United States (USDA-APHIS-VS, 2008) but there is no prevalence data for small ruminants in the US (Collins, 2011).
The economic impact is not well quantified, but in Italy the presence of the JD in dairy sheep and goat farms decreased profit efficiency by up to 20% due to impacts on feed efficiency, veterinary care and labor (Sardaro, et. al., 2016). This is supported by studies showing that vaccination for JD results in a significant increase in body condition scores (Huttner, et. al., 2012) and consequently, profitability (Gautam, et. al., 2017). There is no vaccine for sheep and goats approved approved in the USA. Some studies find that JD can decrease fertility (Kostoulas et al., 2006c) which can also decrease profitability. Clinical JD was found to be associated with production losses associated with lower live weight, fleece weight and fewer lambs born, with a 46% reduction in productivity (Morris, et. al., 2006). In New Zealand, animal deaths confirmed to be JD were 0.6 years younger than animals dying from other causes (Gautam, et. al., 2017).
Johne’s disease is spread through fecal-oral transmission from infected adults to susceptible neonates (Whittington and Sergeant, 2001). Modern bovine dairy operations adjust management to protect the newborn calf from JD by quickly removing the calf to a manure free location (Windsor, 2015). However, many sheep and goat farms do not remove newborns from adults. They also utilize pasture, where the organism can be spread via ingest of contaminated forage (Sweeney, et. al., 2012). Testing for JD is less commonly done where the economic production value of the animal is too low to justify the cost. Our goal is to do surveillance testing in Northern New York as a representative region which can be compared to surveillance in Ontario, Canada. Through partnership with NYSDAM, farmers will be able to participate in testing to help determine risk of JD in their herd, develop management strategies to reduce future risk and control the infection if present.
- - Technical Advisor
- - Producer
- - Technical Advisor (Educator and Researcher)
- - Technical Advisor (Educator and Researcher)
- - Producer
This second phase of research will focus on the goat herds of Northern New York as this is a growing segment of the small ruminant industry in the region. In the last 2 years, 60 farmers met in the area to work on developing a market for goat dairies. This is also seen by looking at the 11% increase in the goat inventory of New York from 2019 to 2020 (USDA, 2020), one of the highest increases in population percentage in the country. A survey of goat herds (both dairy and meat) in Lewis, Jefferson, St. Lawrence, Franklin, Clinton and Essex Counties will be distributed to herds identified by Cornell Cooperative Extension, NYS Department of Agriculture and Markets and collaborating veterinarians with an interest in small ruminant health. The region will be focused on in order to better compare infection in sheep done in 2019 to infection level in goats. The survey will look for patterns for high risk of contagious diseases, such as JD, due to movement of animals from other farms, known infected animals, and/or animals with signs of “fading.” Twenty-two herds interested in participation and with 15 adult animals will be randomly selected for testing, making sure herds in every county are included. If 22 herds of the appropriate size cannot be identified, herds will be included until 330 animals are enrolled. The only requirement for inclusion will be willingness to participate in testing and willingness to enroll in the NYSSGHAP program if not already enrolled.
Sample and additional data collection for those 22 herds on management practices will be done by New York State Department of Agriculture and Markets field veterinarians through the New York State Sheep and Goat Health Assurance Program (NYSSGHAP). NYSSGHAP is not only a management tool for farmers to collaborate with their veterinarian, but the program also has a budget to compensate private practice veterinarians for their participation in the meeting and sample collection. This assists with budget constraints and optimizes our economic focus onto the research and decreases labor costs. Herd veterinarians are invited to be part of the NYSSGHAP meeting to discuss potential improvements to management strategies, help educate herd owners on Johne’s disease and collect samples; and can recuperate the cost of their time through the NYSSGHAP voucher. Enrolled flocks will have 15 semi-random adult animals 2 years of age or older will be sampled. Each animal will have 4-6 ml of blood taken from the jugular vein and 10-15 grams of feces taken via rectal sampling. These samples will be sent to the Wisconsin Veterinary Diagnostic Lab for fecal culture, fecal PCR and blood ELISA in order to replicate the prevalence statistics run in Ontario, Canada so that they can be compared given the geographical proximity. The blood ELISA test screens for antibodies to the JD organism. The ELISA test will be done using 3 different commercially available protocols, however, only the set of results from an FDA approved test method will be reported to the producer. However, the information from running all three tests will allow for comparison of the different test methods and validation for future use of non-FDA approved test methods. The PCR test screens for the DNA of the JD organism (alive or dead bacteria) using the ThermoFisher VetMAX Gold MAP Detection kit with the AM1840 fecal extraction kit. A second PCR will also be run using multiple targets for MAP (Imirzalioglu, et. al., 2011) looking for the IS900, 251 and F57 genes. Fecal cultures are used to test for live JD organism and are performed using Versa Trek Johne’s culture system (Trek Diagnostic Systems Inc.). This is the most sensitive test but requires an extensive incubation period. The Trek system uses 2 gram of feces diluted in sterile water, followed by two overnight enrichments in broth with antibiotics. Afterwards, the sample is mixed with the manufacturer’s proprietary media and incubated in capped bottles for 56 days for caprine samples. The Versa Trek System detects pressure changes in the head space of the bottle caused by the growth of the JD organism and plots those changes on a graph, which determines positivity. All samples are confirmed using acid-fast staining and positive samples are also confirmed using PCR for the IS900 gene.
Number of animals to be sampled was determined using the sample size formula 2.4, with additional control for clustering with equation 2.9 in Veterinary Epidemiological Research (Dohoo, et. al, 2014) to ensure that the statistics would be significant. An estimation of true prevalence will be calculated using Bayesian modeling in the statistics program R Studio (R Studio, Boston, MA), which will take into account the sensitivity and specificity of all three test methods, helping control for the potential false negatives of each test.
During the summer and fall of 2020 we developed the farm survey and emailed it to our Extension Sheep and Goat Update list. Dr. Scillieri Smith worked with veterinarians in the region to have them encourage their goat clients to participate. By early January 2021 we had 38 responses. There are several more farms we expect to survey during their NYSSGHAP renewal as well. We are currently coordinating sampling dates with local veterinarians and farmers. Five farms have been sampled so far. No results have been returned yet. We should be able to meet our stated number of samples assuming there are no more restrictions on farm visits.
We are following CoVid recommendations while doing farm visits and sampling.
Some preliminary results of the survey compiled by Dr. Scillieri Smith:
Education & Outreach Activities and Participation Summary
Enrollment in NYSSGHAP for the enrolled flocks will provide direct and personalized education to farms in the region. The information collected in this study can then be presented across the state by NYS Department of Agriculture and Markets field veterinarians at continuing education events along with discussion at other NYSSGHAP meetings with individual producers. Statewide distribution of information will also occur at the Cornell Cooperative Extension Agriculture In-Service Day where a poster describing the project will be on display. Cornell Cooperative Extension livestock educators will be able to present the results at sheep and goat meetings directed at producers with support from Betsy Hodge. Producer meetings will take place across the region with 3 meeting locations being offered. One meeting will be recorded and posted online for wider distribution. Regional presentation of the information will occur through poster presentation at the Cornell Sheep and Goat Symposium if a larger presentation of the information is not invited. Collaborators will work together to generate articles directed at producers and veterinarians. A peer reviewed publication will be written after this second year of research to cover the information for both the sheep and goat population.