Diagnosis and Control of Johne's Disease (2003) / Chapter Skim
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2. Johne's Disease in Domesticated and Wild Animals
2. Johne's Disease in Domesticated and Wild Animals
Pages 16-44
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From page 16... ...
However, it is important to consider how the disease also is exhibited in other domesticated and wild animals. The significance of species over than dairy cattle as potential sources of exposure could increase as control programs are implemented and as within-herd transmission declines on dairy farms.
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From page 17... ...
Rocky Mountain bighorn sheep (Ovis canadensis Aoudads (Ammotragus lerviaJ Mouflons (Ovis musimon) Rocky Mountain bighorn goats (Oreamnos americanus)
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From page 18... ...
Stage II: Subclinical Disease Most animals in Stage II JD are adults that are carriers of Map. The animals do not exhibit clinical signs typical of JD, but they sometimes have detectable antibodies or exhibit altered cellular immune responses.
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From page 19... ...
Although the organism can sometimes be cultured from sites distant from the gastrointestinal tract, extraintestinal lesions are rarely detected. When extraintestinal lesions are present, the liver, other parts of the GI tract, and the lymph nodes are the most common sites.
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From page 20... ...
Diseases with similar clinical signs in small ruminants include chronic intestinal parasitism, internal abscesses such as those caused by Corynebacterium pseudotuberculosis, chronic hepatic disease, and chronic malnutrition (Beeman et al., 1989~. Clinical signs thus are not a reliable indicator of the presence or absence of Map infection in sheep or goats (Whittington and Sergeant, 2001~.
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From page 21... ...
. Similar histologic changes and involvement of mesenteric lymph nodes also characterize naturally infected animals in subclinical stages of disease.
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From page 22... ...
Categories 2 and 3 represent disease progression into adulthood, with failure of effective immune mechanisms. Category 2 Animals in this category exhibit more extensive lesions in the ileal Peyer's patches, with granulomas extending into the submucosa, and with obvious presence of organisms histologically but no visible gross lesions.
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From page 23... ...
In some cases, nodular foci of caseous necrosis with mineralization have been described in the mucosa, submucosa, serosa, lymphatics, and particularly in the mesenteric lymph nodes, which could be easily confused with signs typical of M bovis or M
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From page 24... ...
, although reports of such cases are rare. Lesions in these species generally consisted of granulomatous enteritis and mesenteric lymphadenitis with the presence of organisms, but often without clinical signs.
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From page 25... ...
Differences in sampling design and diagnostic strategies make direct comparison of He studies difficult, but critical evaluation of published surveys suggests considerable variation in the prevalence of infected herds in different countries and within specific geographic areas. The prevalence of Map-infected animals and clinical JD also varies greatly within affected herds.
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From page 26... ...
Quist (1998) summarized the reports of JD in wildlife in the United States and identified only two endemic foci: Rocky Mountain bighorn sheep (Ovis canadensis)
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From page 27... ...
Lactation Transmission In dairy cows, Map has been isolated from mammary gland (Doyle, 1954; Goudswaard, 1970; Taylor et al., 1981) , and up to 35 percent of infected cows with clinical signs shed the organism in milk (Hole, 1958; Goudswaard, 1970; Taylor et al., 1981~.
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From page 28... ...
Cross-Species Transmission It is important to understand the role of cross-species transmission in causing ID outbreaks and in maintaining infection cycles. Molecular strain typing has greatly enhanced knowledge about cross-species transmission of Map.
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From page 29... ...
, but there are no published reports of natural transmission of Map from wildlife to domesticated livestock. There is, however, epidemiologic evidence that having infected farmed red deer on dairy farms increases the risk of JD in cattle (Cetinkaya et al., 1997)
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From page 30... ...
The data on cross-species transmission have important ramifications for control programs. The relatively restricted host range of S strains suggests that the greatest risk for JD in sheep comes from exposure to other infected sheep, rather than from exposure to other species.
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From page 31... ...
At 15°C, Map survived for 98 days in cattle fecal slurry, 182 days in swine fecal slurry, and 168 days in mixed cattle and swine fecal slurries (Jorgensen, 1977) (Table 2-5~.
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From page 32... ...
paratuberculosis Medium Survival Time pH Temp (°C) Reference Pond water 270 Days Lovell et al., 1944 Saline 17-19 Months 38 Larsen et al., 1956 Tap water 17-19 Months 7 38 Larsen et al., 1956 14 17 Months 5 38 Larsen et al., 1956 1~17 Months 8.5 38 Larsen et al., 1956 Bovine urine No growth observed — 38 Larsen et al., 1956 90% Bovine urine, No growth observed - 38 Larsen et al., 1956 10% feces Cattle fecal slurry 252 Days - 5 Jorgensen, 1977 98 Days 15 Jorgensen, 1977 Swine fecal slurry 252 Days 5 Jorgensen, 1977 182 Days 15 Jorgensen, 1977 50% Swine, 50% 252 Days 5 Jorgensen, 1977 cattle fecal slurry 168 Days 15 Jorgensen, 1977 Water Some information is available about water-related factors important for the growth of MAC and Map.
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From page 33... ...
with increasing pH; other non-mycobacterial counts were unaffected. Using a linear-regression model, eighty-three percent of the variation in mycobacterial counts from brook waters could be accounted for by peatlands in the drainage area, chemical oxygen demand, concentration of potassium, and pH.
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From page 34... ...
Studies currently leave the question of the effectiveness of heat treatment unresolved because of methodologic differences and the difficulty of quantifying viable Map organisms, and further work is warranted (Collins, 1997~. A more pressing question is whether to implement changes in pasteurization and sterilization procedures before the zoonotic potential of Map has been clarified.
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From page 35... ...
paratuberculosis Response to Heat Treatment, Pasteurization, and Over Processes Treatment . Incubation Inoculation Treatment T Duration p i d Result Reference Waste milk n/a 150°F Heat 30 min 28 weeks Complete Stabel, 2001 inactivation Milk 104 cfu/mL O kGy Ionizing 1.2 kGy/h Unspecified Complete Stabel et al., radiation inactivation 2001 104 cfu/mL 5 kGy Ionizing 1.2 kGy/h Unspecified Complete Stabel et al., radiation inactivation 2001 104 cfu/mL 10 kGy Ionizing 1 .2 kGy/h Unspecified Complete Stabel et al., radiation inactivation 2001 108 cfu/mL O kGy Ionizing 1.2 kGy/h Unspecified Complete Stabel et al., radiation inactivation 2001 108 cfu/mL 5 kGy Ionizing 1 .2 kGy/h Unspecified Complete Stabel et al., radiation inactivation 2001 108 cfu/mL 10 kGy Ionizing 1 .2 kGy/h Unspecified Complete Stabel et al., radiation inactivation 2001 Colostrum 104 cfu/mL 63°C Heat 30 min 16 weeks Reduction Meylan et al., 1996 104 cfu/mL 20-23°C n/a Unspecified 16 weeks Reduction Meylan et al., 1996 103 cfu/rnL 63°C Heat 30 min 16 weeks Reduction Meylan et al., 1996 103 cfu/mL 20-23°C n/a Unspecified 16 weeks Reduction Meylan et al., 1996 102 cfu/mL 63°C Heat 30 min 16 weeks Reduction Meylan et al., 1996 102 cfu/mL 2~23°C n/a Unspecified 16 weeks Reduction Meylanet al., 1996 Raw cow's milk 106 cfu/mL 72°C Heat 15 see Unspecified Reduction Grant et al., 1 999 106 cfu/mL 75°C Heat 15 see Unspecified Reduction Grant et al., 1999 106 cfu/rnL 78°C Heat 15 see Unspecified Reduction Grant et al., 1999 (continues)
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From page 36... ...
36 Table 2-6. (continued)
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From page 37... ...
After uptake by the M cells, Map bacilli are transferred to underlying lymphoid tissue. Dissemination via the bloodstream can then occur, with subsequent localization to secondary sites—the liver, spleen, and peripheral lymph nodes.
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From page 38... ...
In animals that fail to contain the infection, replication within tissues progresses, and more and more of the intestinal lining (mucosa) and regional lymph nodes are infiltrated by macrophages filled with mycobacteria.
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From page 39... ...
Immune Response Efforts to dissect the immune system and identify the mechanisms that regulate the immune response to pathogens have involved the use of multiple laboratory species, especially the mouse. The use of inbred mouse strains with inherited differences in susceptibility to infectious agents, and knockout mice missing genes encoding molecules involved in development of an immune
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From page 40... ...
The WC1+ population may comprise 30 to 50 percent of lymphocytes in peripheral blood of young animals. Except for the spleen, the WC1+ and WC1- y6-T-lymphocytes are present in similar proportions in secondary lymphoid tissue and in epithelial tissues at points of entry of pathogens (Wyatt et al., 1994, 1996~.
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From page 41... ...
Direct killing of bacteria is mediated by secretion of perforin and granulysin at the sites of infection (Canaday et al., 2001; Dieli et al., 2001; Smyth et al., 2001~. Down-regulation of secretion of IL-12 promotes differentiation of CD4+ lymphocytes with a type 2 cytokine profile dominated by secretion of IL-4.
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From page 42... ...
The response elicited may lead to either resolution and sterile immunity, or to immune control of infection, with the pathogen persisting in a dormant state or replicating at a low rate. Elucidation of how different pathogens influence the evolution of an immune response is crucial to understanding how to develop efficacious vaccines against known and emerging pathogens (Zinkernagel, 2000~.
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From page 43... ...
It is not possible, however to use those indicators to distinguish between animals that have developed sterile immunity and those with latent infections. If immune control is lost in latently infected animals, disease can progress slowly through subclinical to clinical stages, with associated lesions.
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From page 44... ...
Preliminary reports from the Map sequencing project demonstrate overall 99 percent sequence identity between Map and MAC. The Map genome size, at 5.5 million base-pairs, appears larger than that of M
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