Browsing by Author "Wolf, Robert"

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    Control of Mycobacterium avium subspecies paratuberculosis on Western Canadian dairy farms: Prevalence, diagnostics and risk factors
    (2015-01-08) Wolf, Robert; Orsel, Karin
    Mycobacterium avium subspecies paratuberculosis (MAP) causes Johne’s disease (JD), a chronic, nontreatable enteritis of ruminants. The pathogen causes substantial losses to the dairy industry and might be associated with Crohn’s disease in humans. Eradication of MAP through programs that are solely based on ‘test and cull’ is ineffective because current tests lack sufficient accuracy for reliable detection of infected cattle. Consequently, current MAP control programs focus on prevention of new infections through implementation of best management practices. The overall aim of this thesis was to evaluate the Alberta Johne’s Disease Initiative (AJDI), a management-based MAP control program. Research in this thesis focussed on estimating MAP herd-prevalence, evaluating environmental samples as a diagnostic tool, identifying risk factors for MAP infection, and identifying factors that influenced management improvements. A total of 370 farms participated in the AJDI and were visited annually by their herd veterinarians who conducted risk assessments, collected environmental fecal samples, and discussed management changes. Sixty-eight percent of Alberta dairy farms were MAP-infected and environmental samples collected from lactating cow alleyways and manure lagoons were most frequently culture-positive, suggesting that these samples are important to guarantee high environmental sample accuracy. Furthermore, farms with manure-contaminated cattle and pens, poor feed hygiene, or high purchase rates and low purchase precautions were more likely to be MAP-infected; therefore; improvements in these management areas might be most effective in controlling the spread of MAP. Although most farms subsequently improved management, positive test results and agreed management changes increased the rate of management improvements (which were cost effective). It is noteworthy that the current program overlooks hygiene of young cattle, because 2% of heifers shed MAP which indicates that management improvements in this area may reduce MAP transmission.
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    Control of paratuberculosis: who, why and how. A review of 48 countries
    (2019-06-13) Whittington, Richard; Donat, Karsten; Weber, Maarten F; Kelton, David; Nielsen, Søren S; Eisenberg, Suzanne; Arrigoni, Norma; Juste, Ramon; Sáez, Jose L; Dhand, Navneet; Santi, Annalisa; Michel, Anita; Barkema, Herman; Kralik, Petr; Kostoulas, Polychronis; Citer, Lorna; Griffin, Frank; Barwell, Rob; Moreira, Maria A S; Slana, Iva; Koehler, Heike; Singh, Shoor V; Yoo, Han S; Chávez-Gris, Gilberto; Goodridge, Amador; Ocepek, Matjaz; Garrido, Joseba; Stevenson, Karen; Collins, Mike; Alonso, Bernardo; Cirone, Karina; Paolicchi, Fernando; Gavey, Lawrence; Rahman, Md T; de Marchin, Emmanuelle; Van Praet, Willem; Bauman, Cathy; Fecteau, Gilles; McKenna, Shawn; Salgado, Miguel; Fernández-Silva, Jorge; Dziedzinska, Radka; Echeverría, Gustavo; Seppänen, Jaana; Thibault, Virginie; Fridriksdottir, Vala; Derakhshandeh, Abdolah; Haghkhah, Masoud; Ruocco, Luigi; Kawaji, Satoko; Momotani, Eiichi; Heuer, Cord; Norton, Solis; Cadmus, Simeon; Agdestein, Angelika; Kampen, Annette; Szteyn, Joanna; Frössling, Jenny; Schwan, Ebba; Caldow, George; Strain, Sam; Carter, Mike; Wells, Scott; Munyeme, Musso; Wolf, Robert; Gurung, Ratna; Verdugo, Cristobal; Fourichon, Christine; Yamamoto, Takehisa; Thapaliya, Sharada; Di Labio, Elena; Ekgatat, Monaya; Gil, Andres; Alesandre, Alvaro N; Piaggio, José; Suanes, Alejandra; de Waard, Jacobus H
    Abstract 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.
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    Evaluation of age-dependent susceptibility in calves infected with two doses of Mycobacterium avium subspecies paratuberculosis using pathology and tissue culture
    (BioMed Central, 2013-10-07) Mortier, Rienske A. R.; Barkema, Herman W.; Bystrom, Janet M.; Illanes, Oscar; Orsel, Karin; Wolf, Robert; Atkins, Gordon; De Buck, Jeroen; Medicine