Johne's Disease, An Issue of Veterinary Clinics: Food Animal Practice

Michael T. Collins

Description

A comprehensive review of Johne’s Disease (Paratuberculosis) guest edited by Dr. Michael Collins! Topics will include: epidemiology and economics, pathogenesis, treatment and chemoprophylaxis (monensin), genetic resistance, vaccination, diagnostic methods, control of paratuberculosis in beef cattle, control of paratuberculosis in dairy cattle, control of paratuberculosis in small ruminants, paratuberculosis in wildlife and zoological collections, food safety and zoonotic concerns, state and federal efforts at control, international efforts at paratuberculosis control, case studies, and more!

Sujets

• Food Animal
• Veterinary Medicine
• Medical
• Médecine

Informations

• Publié par: Saunders
• Date de parution: 28 novembre 2011
• Nombre de lectures: 2
• EAN13: 9781455712106
• Langue: English
• Poids de l'ouvrage: 1 Mo

Extrait

Veterinary Clinics of North America , Vol. 27, No. 3, November 2011
ISSN: 0749-0720
doi: 10.1016/S0749-0720(11)00061-2

Contributors
Veterinary Clinics of North America
Food Animal Practice: Johne’s Disease
Dr. Michael T. Collins, DVM, PhD
Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin, 2015 Linden Drive, Madison, WI 53706, USA
ISSN  0749-0720
Volume 27 • Number 3 • November 2011

Contents
Cover
Contributors
Forthcoming/Recent Issues
Johne's Disease
Epidemiology and Economics of Paratuberculosis
Pathogenesis of Paratuberculosis
Treatment and Chemoprophylaxis for Paratuberculosis
Genetic Susceptibility to Paratuberculosis
Paratuberculosis Vaccination
Diagnosis of Paratuberculosis
Control of Paratuberculosis in Beef Cattle
Control of Paratuberculosis in Dairy Herds
Control of Paratuberculosis in Small Ruminants
Paratuberculosis in Captive and Free-Ranging Wildlife
Food Safety Concerns Regarding Paratuberculosis
State, Federal, and Industry Efforts at Paratuberculosis Control
International Efforts at Paratuberculosis Control
Index
Veterinary Clinics of North America , Vol. 27, No. 3, November 2011
ISSN: 0749-0720
doi: 10.1016/S0749-0720(11)00063-6

Forthcoming/Recent Issues
Veterinary Clinics of North America , Vol. 27, No. 3, November 2011
ISSN: 0749-0720
doi: 10.1016/j.cvfa.2011.08.001

Preface
Johne's Disease

Michael T. Collins, DVM, PhD, Email: [e-mail]
Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin, 2015 Linden Drive, Madison, WI 53706, USA


Michael T. Collins, DVM, PhD, Guest Editor
From the late 1800s to 1996, Johne's disease (paratuberculosis) spread among domesticated ruminants globally, emerging as one of the more common and costly ruminant infectious diseases, and prompting publication of the July 1996 issue of Veterinary Clinics of North America: Food Animal Practice devoted to Johne's disease guest edited under the guidance of Dr Ray Sweeney. 1 Since then, there has been a surge in research and development of national Johne's disease control programs around the world. The Johne's Disease Integrated Program in the United States invested over $8 million in applied and basic research on the etiology, Mycobacterium avium subsp. paratuberculosis . 2 In Europe, a multinational European Union program named ParaTBTools stimulated research similar in size and scope. 3 The products of these research programs are evident among the 2305 scientific publications from 1,465 institutions and 5149 authors between 1995 and 2009. 4
This issue of Veterinary Clinics of North America: Food Animal Practice captures this wealth of new knowledge about Johne's disease and translates it into practical terms for veterinary practitioners. Authors of the enclosed articles are internationally recognized experts who work with practitioners and producers on a daily basis, giving them insights on Johne's disease only gained by years of experience and considerable trial and error. This issue provides a basic understanding of Johne's disease epidemiology and pathobiology, practical methods for Johne's disease control on farms, early information on genetic resistance, a description of national and international control efforts, and a glimpse into the future as to whether MAP is a human health issue: a zoonotic pathogen contaminating foods of animal-origin. I gratefully acknowledge the expertise and collegiality of my colleagues authoring this issue.

References

   1. R.W. Sweeney. Paratuberculosis (Johne's Disease). Vet Clin North Am Food Anim Pract . 12(2), 1996.
   2. JDIP http://www.jdip.org/ . Accessed August 18, 2011
   3. ParaTBtools http://www.vigilanciasanitaria.es/paratbtools/index.php . Accessed August 18, 2011
   4. M. Kaefska, K. Hruska. Analysis of publications on paratuberculosis from 1995 to 2009 with emphasis on the period from 2005 to 2009. Vet Med . 2010;55:43-54.
Veterinary Clinics of North America , Vol. 27, No. 3, November 2011
ISSN: 0749-0720
doi: 10.1016/j.cvfa.2011.07.012

Epidemiology and Economics of Paratuberculosis

Jason E. Lombard, DVM, MS, Email: [e-mail]
National Animal Health Monitoring System (NAHMS), United States Department of Agriculture, Animal Plant Health Inspection Service, Veterinary Services, Centers for Epidemiology and Animal Health, 2150 Centre Avenue, Building B-2E7, Fort Collins, CO 80526-8117, USA

Keywords
• Johne's • Paratuberculosis • Epidemiology • Prevalence • Economics
Paratuberculosis, or Johne's disease (JD), is caused by the bacterium Mycobacterium avium subsp. paratuberculosis (MAP). Although JD is frequently used in discussing MAP infections, the use of JD technically should be restricted to the clinical manifestation of MAP infection; the preclinical stage being called paratuberculosis. The first reported occurrence of JD, which was initially thought to be an intestinal form of tuberculosis, was in the early 1800s in Germany and was later described by Drs Johne and Frothingham. 1 In the United States, the first reported case of JD appeared in Pennsylvania in 1908. 2 The disease has since been observed in cattle, other ruminants, and various other domestic and wild animals worldwide. 3 Most of the research on MAP infection has focused on cattle, dairy cattle in particular.
Calves and other ruminants less than 6 months of age are generally considered to be at the greatest risk of becoming infected with MAP. Neonates are likely the most susceptible due to increased permeability of the intestines in the first 24 hours of life. 4, 5 Although there are data to support infection of adult cattle with MAP, 6 calfhood infection is far more important in most herd situations. The average incubation period of MAP infection in dairy cattle has been estimated at 5 years, 7 with the incubation period being inversely related to the MAP dose—that is, the more MAP consumed, the shorter time period before displaying clinical signs. Some infected cattle may not show clinical signs within their productive lifetime. 8 One of the difficulties in controlling MAP infection is that animals frequently shed MAP in feces prior to showing any clinical signs, thus insidiously contributing to spread of the infection.
A report from the 1920s suggested that MAP infection was present at low levels in the US cattle population. 9 The report warned that the problem should be dealt with before it became endemic like tuberculosis and brucellosis were at the time. The interesting aspect of the history of MAP infection in the United States is that our predecessors not only predicted the disease would continue to spread but also recommended diagnostic tests and control strategies that remain the basis of current programs. 10 Unfortunately, despite the early warnings and availability of diagnostic tools, the infection has continued to spread. The tools currently available (diagnostic tests and control programs) will be discussed in depth in other articles in this issue.

MAP: Characteristics, Environmental Persistence, and Heat Resistance
MAP is a gram-positive, acid-fast organism that has a rough, thick, and waxy cell wall ( Fig. 1 ). All Mycobacterium species other than MAP produce the iron-chelating agent mycobactin. 1 Since iron is required for replication, MAP is considered an obligate parasite of mammalian cells where iron is readily available to the organism and mycobactin is not needed. 11 MAP preferentially infects macrophages upon entry into the host and thus is considered a facultative intracellular pathogen. 12, 13

Fig. 1 Scanning electron micrograph of Mycobacterium avium subsp. paratuberculosis , ×50,000 magnification.
( Courtesy of Michael T. Collins, DVM, PhD, Madison, WI.)
The tenacious, protective cell wall and propensity to form large clumps of cells allows MAP to withstand a variety of harsh conditions and survive for longer than 1 year in the environment. 14 A study of naturally infected sheep feces found that direct sunlight and UV radiation had the greatest negative impact on MAP survival. Shade, even in the form of grass, increased MAP survival time. 15
In addition to withstanding a variety of environmental conditions, the organism is resistant to heat and has been shown to survive high-temperature, short-time pasteurization (72°C for 15 seconds) if present in sufficient numbers in raw milk. 16 Batch pasteurization of colostrum at 60°C (140°F) for 60 minutes is sufficient to eliminate MAP under most conditions. 17 In a controlled study, viable MAP was not detected in MAP-spiked waste milk samples after 30 minuites at 65.6°C. 18

MAP Prevalence
Prevalence, an estimate of the number of infected animals in a population at a given time, is determined via testing of a sufficient number of animals to produce an estimate with the desired degree of precision. Prevalence can be reported as apparent (test) prevalence where the estimate is the number of animals that test positive divided by the total number of animals tested. Alternatively, true prevalence can be calculated by adjusting the apparent prevalence based on the accuracy of the test used. For example, if a test is used that detects 50% of MAP-infected animals (test sensitivity = 50%) and all animals that test positive are