Bacterial Diseases of the Ruminant Alimentary Tract PDF

Bacterial Diseases of the Ruminant Alimentary Tract 565 12. Roussel Al, et al J Am Vet Med Assoc. 2005:226:773. 13. Koets A, et al. Pev Vet Med....

Bacterial Diseases of the Ruminant Alimentary Tract 565 12. Roussel Al, et al J Am Vet Med Assoc. 2005:226:773. 13. Koets A, et al. Pev Vet Med. Molecular studies of MAP have identified 201093:305 Deer Outbreaks of diarrhea, il-thrift, and 14. Kirkpatrick BW, Shook GE Vet Clin North Am Food a high degree of genetic similarity within the deaths in young deer (-15 months) or bovine isolates, regardless of geographic Anint Pract. 2011:27:559. latent that infection causes sporadic cases origin, indicating that only a few closely 15. Marce C, et al. Prev Vet Med 2011;10:116. with welght loss and temninal diarrhea in 16, van Roermund HJW, et al. lét Microbiol. older deer. related clones may be responsible for wide- 17. 200/122:270. Chiodini RJ, Hermon-Taylor J. J Vet Diagn Invest. dinical pathology Culture and direct PCR of spread intection in cattle, other ruminants, and possibly wildlife. There is a higher degree 1993:5:6 18. Elingson JLE, et al. J Food Prot. 2005,67:966. eces. serologic tests (ELISA, AGlD, and CH and builked tecal cuture tor flock diagnosis. ot genetic heterogeneity among MAP 1s0- lates recoVered from ovine sources. strain 19. Ayele WY, et al Appl Environ Microbiol. 2005:71:1210. Low serum protein and marked hypoalbuminemia in affected animals more readily intects sheep, goats, and deer, whereas strains tend 20. Codden S, et al. J Dairy Set. 2006;893476. Lesions Chronic granulomatous enteritis, sheep to be more Spe 21. Smith RL, et al. J Dairy Sch. 2009:92:2653. cihc and are less commonly isolated from regional lymphangitis, and lymphadenitis in 22 MeNab WB, et al Can J Vet Res. 1991:55252 other species. However, cograzing of sheep sneep and goats caseous lesions in deer. and beet cattle 23. Lombard E, et al. J Vet Diagn Invest. 2006;18:448. agnostic confimation Presence ot gross means that thes suraln is 24. Wilson D), et al. A Vet Res. 1995958:1891. being isolated more often from beef cattle, 25. Lombard E, et al. Am} Ver Med Assoc. intestinal lesions, culture and PCR of whereas dairy cattle be intected predomi 2005;227:1975. rganism trom tissues and histopathology. nanly with the C strain. 26. et al Microbes Infect. espedially terminal ileum, leocecal valve eyanathan M, 27. Gl Co, et al. J Food Prot. X01 1:74:480. 2007:9:1567. and lymph node, and mesenteriC lymph EPIDEMIOLOGY 28. Collins MT. Vet Clin North Am Food Anim Pract. nodes. 1 1,27:631. Occurrence, Morbidity, and Mortality 29. Nelen 55, Toft N. vet Microbrol. 2008;1 29.217, Treatment No treatment of significant value. Sheep and Goats 50. Colins MT, et al JAm Vet Met Assoc. Control ldentity and eliminate cinical cases Paratuberculosis occurs worldwide and is ofmajor importance in in 2006;229:1912. and subdinicaly infectecd animals. lest flock sheep temperate 31. Collins MT, et al Clin Diagn Lab Immunol. a herd to identity high-prevalence age 2005;12:685. groups and make these a priority for climates and some humid, tropical areas. The prevalence is greatest in animals kept 32. Cidk RE. Virulence. 2010:2:337. aulling. Improve management and hygiene intensively under climatic and husbandryy 33. Cick RE. Virulence. 20112131. D of conditions, which are conducive to the minimize spread infection with emphasis on avoiding intecton of newborn spread ot intection. PARATUBERCULOSIS (JOHNE'S animals. vaccination ot sheep and goats The history of ovine Johne's disease (OJD) DISEASE): SHEEP, GOATS, prevents clinical disease but not infection and fecal shedding in lceland is example of the spread of an CERVIDS, AND CAMELIDS this disease from a point source. Briefly, 20 Differential diagnosis list apparently healthy Karakul stud rams were Diarrhea in adults trom in imported Germany 1933. After 2 SYNOPSIS Gastrointestinal parasitism months quarantine they were distributed to Etiology Mycobacterium avium subsp. Bacterial intections: Yersiniosis and salmonellosSis 14 Tarms, and the irst clinical case of OJD in paratuberculosis (MAP). was diagnOsed 1938. Gradually, infection spread from five originally infected farms Chronic weight loss in sheep and goats Epidemiology Transmitted by fecal-oral and, after 18 years, 20% to 30% of the farms in Dute. Prenatal infection occurs in sheep nternal abscesses Caseous lymphadenitis the main sheep breeding areas were infected. and deer but not contfirmed in goats. The annual morbidity of sheep during the Source of infection is infected dam or Caprine arthritis-encephalitis Ovine progressive pneumonia epidemic averaged 8% to 9% in affected areas, ontaminated pasture. Infection more likely soon after brth but age-related resistance Dental disease up to 40% on individual farms. andInwasNew Zealand, OJD was first reported D intecton is not as pronounced as in GID, agar gel immunodiffusion: CF complement in the South Islandin 1952, and by 1970 atte. In sheep and goats the incubation fration: ELISA, enzyme-inked immunosorbent say; PCR polymerase chain reaction. more than 150 tarms were confirmed as period is shorter than for cattle, usually 2-5 It ears, but increased stress (nutritional and inlected. was detected in the North Island gastrointestinal parasitism) can induce cases in 1972, and by 1979 284 farms were known earlier. High flock and within-flock to be intected. More recent estimates of prev ETIOLOGY prevalence of infection in sheep in many alence are 76% of sheep flocks (95% confi- cDuntries. A high prevalence in farmed The causative agent of paratuberculosis in dence interval [CI] 70%-81%) and 46% of deer in New Zealand and some other ruminants is MAP a slow growing acid-fast deer herds (95% CI 386-55%). In Aust ralia, OJD was tirst confirmed in 1980 and by 1999 cOuntries. Deer can be infected with both aerobic MAC. mieroorganism forming part of ne bovine and ovine stains of MAP with Although MAP is an obligate intracel had spread to most states. It is presumed that the former being more infective and lular pathogen requiring host for intection a replica originated from sheep imported pathogeniC tion, it can survive for longer than 1 year in Irom New Zealand in the 1970s, and it is dinical signs the environment. MAP has been subdivided estimated that at least 40% of flocks are now into Sheep Chronic wasting disease of adult two main lineages designated as the slow infected in some areas. In South Africa, the sheep; diarrhea not a distinct dinical growing type l (or S tor sheep) and the faster disease was unknown until an infected fnding. Common cause of emaciation in growing type ll (or Ctor cattle) according to Merino ram was imported in 1967 and it ewes, although cases can occur in 10- to the species trom where these lineages were then spread among sheep farms in the first isolated. Type I strains appear to have a 15-month-old sheep in high-prevalence Tiocks. strong host preterence for sheep and are Western Capeand Eastern Cape provinces in the 1990s. Infection is also confhrmed in more virulent for this species, whereas type Goats Chronic progressive intractable diarrhea Irom South America,ofNorth America, and Europe and emaciation extending9 over several strains are cattle more commonly isolated in which 74% 38 dairy sheep locks in the weeks and months. Generally, a higher and a range of other species. Genome sequencing has conhrmed that an intermedi- Marche region of Italy tested positive to a prevalence in milch compared with fiber commercial ELISA for Johnes dise ase. breeds. ate or type l l strain is a subtype of the S Clinical signs are progressive emaciation, strain. with intermittent diarrhea n some sheep. 566 Chapter 8 Diseases of the Alimentary Tract-Ruminant 566 Chapter 8 Diseases of the Alimentary Tract-Ruminant Sheep are easily infected experimentally, estimate because of the relative insensitivity from clinically affected ewes (83%) com- with doses from 10' to 10' viable bacteria reliablyinducingintections in 12- to 16-week of screening tests, uncertainty of antemor- tem diagnosis, and he failure to report pared with 1.6% from subclinically affected and none trom uninfected ewes. old Merino lambs. Infected animals can cases unless a speciic survey or eradication excrete large numbers of the organism, up to 10 to 10 per gram ot leces, but some can program is undertaken. Deer Deer can be infected with either the cattle or spontaneousty recover irom intection. Sheep sheep strain of MAP but the cattle strain Mortalities can vary considerably OJD was first diagnosed in in Australia in appears to be of higher infectivity." In New between tarms, but OJD can cause signincant central New South Wales in 1980. The disease Zealand and elsewhere deer are cograzed financial losses. For example, in an Austra- has a highly clustered dist ribution indicating with both sheep and cattle. However, model- ian the associated ing of the dynamics ot Johne's disease in study disease was mortality rates from 2.1% to 17.5% and a with spread between neighboring properties and by sheep trading. In 2000, surveys found farmed deer found that if mixed strains of decrease in farm gross margin ot from 2.2% that the 95% probability limits for flock MAP were present, a reduction in infectivityy to 15.4%."On average, these losses were esti- prevalence in low-, moderate-, and high- of 30% would be suficient for a dominant mated to cost affected farms at least $13.700 strain to outcompete a less intective one. This USS10,500 per year. In Cyprus, where sheep prevalence regions in 0.04% New doutn299% Wales were suggests that mixed infections with C and S are larmed semi-intensively tor milk to to 1.5%, 8% to 15%, and to 39%, strains of Map in a deer herd might not be respectively, whereas all other states had an produce cheese, ewe mortalities can be as high as 46 per year. 1The disease is being uPper 9/.3% probability umit ot 1o or less. common, because the Cstrain would become Based on these estimates, from 6% to 10% ol dominant.".Js recognized with increased frequency in goats flocks in New South Wales and 2.4% to 4.4%6 and can cause large losses. In Australia. o tlocks Australia-wide were estimated to be Risk Factors Johnes disease occurs in dairy goat breeds infected. Over 80% of atfected flocks were Sheep and Management with endemic foci of infection in southeast located in a relatively small geographic area of A relative resistance to infection with ern Australian states. increasing age is a feature of Johnes disease New South Wales, whereas Queensland and Western Australia had a flock prevalence of in but is cattle less pronounced with OJD. For Deer, Camelids, and Exotic Species less than 1%. Subsequently, a review of the example, experimental infection with a high MAP has a broad host range, with deer OJDcontrol strategy irom 2007 to 2012 tound dose of MAP induced lesions in both lambs that although the tran smission of infection and adult ewes; however, the were restricted alpacas, llamas, camels, and captive and free- living wild ruminants, including bighorn from some low-prevalence areas had been disease to tocal granulomas within lymphoidto tissue sheep. Rocky Mountain goats, aoudads, restricted, the had spread widely, and in the ewes, whereas they progressed more mouflon sheep, reindeer, antelope, and yaks many areas were classified ashaving a low that widespread lesions in the lambs" being susceptible. A high prevalence was prevalence in 2000 now had a medium or In Australia and New Zealand, fine wool detected in farmed alpacas in Australia in the high prevalenceof infectedflocks. Merino sheep have a higher mortality from 1990s,but a concerted control program has OJD than other sheep breeds. Within large Virtually eliminated this disease trom Aus- Methods of Transmission wool-producing flocks wethers often have a tralian alpaca tlocks. Spread of the organism from tarm to farm is higher prevalence of intection. 1his is prob. Outbreaks of Johne's disease have usually caused by trading of livestock, which ably related to higher stocking rates for this occurred in farmed red deer, and the inci- class of animal and poorer nutrition, both dence in some regions. are unknon infected carriers and shedders of the organism. This results in clusters of quality and amount of pasture, relative to the is increasing example, Johnes disease was For recognized in ewe portion of the flock." Poorly controlled farmed deer in New Zealand in the 1980s infected flocks. Lateral spread between infections with flocks, through contact between intected and internalassociated parasites andwith under- and by 2000, the disease had been diagnosed in 299 herds, or 6% of the commercial deer uninfected sheep in common areas such as yards or roads, or the movement of feces nutrition are both increased prevalence of infection and clinical an in 90% of these across boundary fences, can then occur. herds New Zealand. Over farms were identified from lesions in mesen- Intrauterine infection has been disease. For example, in a cross-sectional study of 92 Merino flocks in southeastern con teric and ileocecal lymph nodes at meat inspection, whereas only 6% were detected firmed in sheep and deer, but most intection Australia, key risk tactors associated with a with MAP occursneonates by the fecal-oral route. higher prevalence ot OD incuded sheep whose dams had been in low body condition through the presence ot clinicaly aftected This can occur by suckling trom an animals. The disease is now regarded as infected dam via contaminated teats or at lambing time, sheeP that had experienced endemic in farmed deer in New Zealand ingestion of fecally contaminated pasture. a longer period of growth retardation during (46% of herds) and has also been detected in and farmed red deer in the UK, Belgium, Holland, their lifetime, highforstocking rates." In Sheep this was study vaccinating assoCialed with a 2 more than years signifcantly lower the Czech and Republic. Young deer infected with MAP can develop disease within 5 to 7 Clinically affected sheep excrete umber of organisms, often over 10' viable large prevalence of MAP infection. months, with outbreaks affecting up to 20%, MAP per gram of feces. Thus the output of 1 Flocks shorn in winter and farms with a or can remain latent for many years. Thus to 2 kg of feces from a single clinical animal high percentage of improved pastures con- many infected deer will be culled before they over day is sufhcient to infect many taining subterranean clover (the latter typ show any clinical signs. animals, with an intective dose of S-strainn cally associated with higher stocking rates) The epidemiologic impications of deer, MAP being as low as l0 organisms. were also associated with a higher prevalence cattle, and wildlife comingling on the same Ovine trichostrongylid larvae (Haemon- of OD in tlocks in southeastern Australia. pasture are not fully known, but the rate of dus contortus, O. cireumcincta, 1. colubri or- Exposure of young sheep to a high level of infection can be similar in both domestic mis) may become contaminated with MAPP pasture contamination with MAP was iden- species and so each can be a source of and may play a role in the transmission of tifed as a risk factor tor a higher prevalence C-strain MAP for the other of severe OJD lesions and mortalities in the organism, ess although this is likely to be tar important than direct exposure to this area. Prevalence and Source of Infection pasture contaminated with infected feces. Consistent with these observations, prac The prevalence of Johnes disease infection in flocks or herds within a region is difficult to Fetal infection can occur, with much a proportion of infected fetuses higher identified tices associaled with 1ntensive management, such as a high proportion of introduced sheep, or multiple or foreign breeds, have the organism in leces becomes mixed with associated lymph nodes and, to a lesser as risk factors for OJD in in been identiied Spanish flocks. soil, there is a reduction of 90% to 99% in the apparent viable count of the organism." This extent, in the tonsils and suprapharyngeal lymph nodes. The primary site of bacterial is thought to be caused by binding of bacteria multuplication is the terminal part ot the Deer to The risk factors in outbreaks of Johnes soll particles, which are culture by sedimentation during sample excluded from small intestine and the large intestine. At least three different groups of animals can disease in deer have notisbeen investigated in that they are in preparation. Survival of the organism sheep fecal material applied to soil was great Occur depending on the host-bacteria rela- any detail. However, it likely similar to other species, namely age at expo tionship that becomes established. In the first est size of dose, innate in a fuly shaded environment (55 weeks) group, animals develop resistance quickly, sure, infective the and was least where tecal material and soil control the infection, and do not become the animal, and envi- immune response of ronmental factors. were fully exposed to weather and where vegetation was also removed. The organism shedders (infected resistant). In the second group, the intection is not completely con- survived tor up to 24 weekS on grasS trolled; some animals will partially control that Environmental Risk Factors germinated through infected fecal material the infection and will shed the organism Soil Characteristics applied to the soil surtace in completely An association between high prevalence of shaded baxes and tor up to 9 weeks on grass intermittently, others will become interme- MAP intection in and soil placed in 70% shade. diate cases that are incubating the disease ruminants type and will be heavy shedders of the organism. has been recognized, and the literature on the organism appears to be Dormancy of the pOssiblelinks between the clinical expressiona feature in the Australian environment, In the third group he organis pesists " the intestinal mucosa, and from these of paratuberculosis and deficiency of has macro with the dormancy characteristics related to animals the clinical cases develop. nutrients and micronutrients been genetic elements of MAP that are also present The is reviewed. The evidence implicates regional organism phagocytuzed by macro is soil acidihcation (low pH), excesses of iron in other mycobacteria. However, survival fhnite and signihcant pasture decontamina- phages, which in turntheproliterale in large and molybdenum, and marginal deficiencies tion can occur within a relatively short numbers and infiltrate in intestinal submu- in copper and selenium in a higher preva- cosa. This results decreased absorplion, period. 1his reduces exposure to the organ- chronic diarrhea, and resulting malabsorp lence of Johnes disease. In Australia, mortal Ism and the prevalence of disease." Pasture tion. There is a reduction in protein absorp- ity from decontamination OD was higher on farms with light sandy soils, consistent with studies in dairy can be hastened by pasture management, such as selective grazing with tion and leakage ot protein into the lumen or cattle in Spain. In contrast, a later study of 92 less susceptible hosts or mechanical slashing the jejunum. In sheep, a compensatorY increase in protein production in the liver Merino flocks in southeastern Australia to decrease shade. masks the protein loss, so clinical signs ot found positive a asSsoCiation between nigner h eorganism persists without multipli- muscle wasting appear only when this com- organic carbon, clay, and iron content, cation in for whereas there was a lower prevalence of OJD pasture long periods, and such pastures are intectivee lor up to1 year. The pensatory mechanism fails. Within the mac- viable and on farms with sandy soils."It organism is relatively susceptible to sunlight rophages, the bacteria remain was suggested protected from humoral factors. that MAP may adhere more closely to the smaller clay particles, compared with larger and drying, to a high calcium content, and to high pH of the soil. Continuous contact sand Immune Response particles, and thus be retained in greater with urine and feces reduces the longevity of The first line of defense against invading numbers for a longer period in clay soils. The the bacteria. but the organism can survive for MAP in the ruminant intestine involves M 98 to 287 days in tanks, depending on the association between low soil pH and occur cells (special epithelial cells associated with rence of OJD was inconclusive, although most tarms had relatively acidic soil and a composition and alkalinity soil ofalsotheinfluence slurry. ileal Peyers patches and lymphoid follicles narrow range of soil pH compared with other The alkalinity of the may the severity of the clinical signs. that the actively take up particulate matter from studies. "MAP requires iron lor survival and intestinal contents) and ofphagocytic macthe but is relatively inetficient at che- rophages. in early stages intection, replication, Zoonotic Implications organism is lound in phagocytic macro lating this element compared with many MAP of health other bacteria. Thus an increased concentra- is potentially public cance because, although there is no evidence signifi- phages in the intestine. Once inside the phagosome of an intected macrophage, the tion of iron is hypothesized to increase the of a causal relationship between it and organism interleres with the normal course survival of MAP in soil. The solubility of iron Crohns disease in humans, there is a growing of phagosome sed the maturation into phagolyso lso increases with decrea pH, hence, nerature on the possible association between some, escaping destruction. The infection of frequent association of increased prevalence MAP and Crohn's disease." This is addressed in acidic inactivated macrophages within the intestine of Johne's disease compared with in more detail in the section on Johnes is the first step in establishing persistent alkaline soils. disease of 500 scientific papers cattle, but than more made reterence to this topic Irom intection and the subsequent development of disease. The host immune system begins a Pathogen Risk Factors 1972 to March 2014, averaging around 3.5 series of attacks against MAP-infected mac MAP isan obligate pathogen and parasite ofpapers per month since2009. rophages, initially involving CD4+ T cells, animals, and in theory it can be eradicated The organ ism has been found in raw goat of CD&+ removal of all infected the production lFN.-Y,and cytolytic by the animals. However, milk in Norway and conditions in cheese cells (a Thl response). These cells interactt organism can survive for long periods production have little effect on the viability with the Pl macrophage and each other outside the host. enabling it to persist and of in spread in a grassland environment and with MAR, with viable bacteria found hard and semihard cheese 12 days after produc- through a complex network of cytokines and receptors. Despite this response, MAP stand a periodic lack of suitable hosts. tion. Therefore consumption of cheese man- organisms persist and the immune reaction Survival and Dormancy of Organism utactured from raw goat milk sourced from herds intected with Johnes disease might injures the intestinal epithelial cells. During he early subcinical stages ot in the Environ ment lead to human exposure to MAP. infection, the organísm elicits a cell-mediated Both Sand Cstrains of MAP can be extremely response by the host, characterized by strong persistent in nature, with survival for more PATHOGENESIS delayed-type IV hypersensitivity reactions, than I year. Studies of the survival of S-strain MAP in eas tern Australia indicate that when Following oral ingestion, the organism local- izes in the mucosa of the small intestine, its ymphocyte proliferation,and production of cytokines by stimulated T lymphocytes. As  8 Diseases of the Alimentary Tract-Ruminant 568 Chapter and the disease progresses Irom subclinical to a heavy burden of bacteria, may be one factor may become soft and pasty. Depression evident in goats but are less dinical, the cell-mediated immune response in the development of chronic inflammatory dyspnea are obvious in sheep. wanes and a strong humoral response (1gGI lesions. 1his iS In experimental infections of non-Merino ISotype) becomes dominant. processtor sheep MAP, clear differences with S-strain Other Species (Deer, Camelids, not well understood, but competition antigen between these Thl and Th2 responses were found in the cell-mediated immune and Bison) In deer, Johne's disease is unusual in that it response and outcome ot inlection according probably contributes to this switching Can present as outbreaks of acute disease in to age (1-month-old lambs compared with Alhl response is needed to keep the infec- mature ewes) and he dose ot MAP given young animals, with loss of BW, diarrhea, tion under control, and antibody against MAP does not protect the host against (1.6 X 10 CFU compared with 4 x 10 and deaths as young as 8 months of age, or C-strain MAP is di se ase. LDuring the final stages ol disease, CFU). Lambs given a higher dose devel sporadic more cases in adults. pathogenic, but the S strain can also intestinal lack of antigen-specifnc cell-mediated ped progressive and widespread lesions whereas, in ewes given a higher dose, cause disease. immune response or complete anergy may were smaller and iym- to Similarly, in alpaca (Lama pacos) and result, allowing for rapid dissemination ot lesions conhned phoid tissue. Ewes given the low dose were ama (. glama) weight loss, emaciation and the infection throughout the host. There appears to be an immune spec PCR positive after infection, but no micro diarrhea are reported in both young (8-1 and months) and older animals. Some infected trum, and no serologic or cellular immunity scopic lesions were detected tissues were may show n o clinical signs Johne's culture negative at 110 and 220 days. of test will identify all animals in the spectrum. animals disease but are positive on fecal culture or There are infected-resist ant animals that As infection progresses, the bacteria are control their infection but are unable to com- carried by macrophages to other sites, par serologic testing. Many cases have grossly enlarged mesenteric lymph nodes, which the can pletely eliminate the organism. These animals ticularly the uterus, the fetus, and do mammary gland. Vaccination against Johne's be confused with and tre lymphosarcoma, infection not react in antibody and assays, only to rarely or never shed organisms, respond the disease does not of MAP in prevent intection or but it restricts shed- the quently widespread mycobacterial in organs other than the intestine. ymphocyte transtormation test because ding sheep, their circulating lymphocytes are sensitized. cellular response to the intestinal wall and thus prevents the onset of clinical disease. In American bison (Bison bison) the cini- cal signs and lesions are similar to those in In the intermediate stage, the animal fails to catte, with gross lesions in the distal small control the infection, antibodiesshed appear in Disease progression is associated with intestine and enlarged mesenteric lymph ad organisms are feces. "In the stage of clinical disease, the in the immune dysfunction, and although the exact mechanisms are not fully understood many node organisms are shed in the feces and the anti- differences have been described. A Thl cell1- body responses and skin tests are variable. mediated response, with secretion of IFN-Y CLINICAL PATHOLOGY 1S predominant soon after exposure to MAP. In an infected flock or herd, animals can be in Development of Lesions infection alters progresses to mullibacillary one of the tollowing tour groups In sheep with OJD two distinct histologic lesions, increased thisexpression ofTh2IL-4response, to a with and IL-10, Clinical disease and be shedding the organism, usually in large numbers ypes ot granulomatous enteritis occur, with a significant relationship between the infil- whereas in sheep with paucibacillary lesions Subclinical infection and be shedding trating cell type and the degree ot intestinal the Thl response tends to remain predomi- the organism, often intermittently and mycobacterial infection. At the two ends of nant. However, the immune response is in intermediate numbers Infected, but neither ill nor shedding the spectrum of lesions are these two widely complex and not "all or none, with a mix of fecal differing forms: cell-mediated and antibody responses ocur enough bacteria to be positive on Tuberculoid extreme with a strong ring. Changes described in the ileal and culture (inlected resistant) cell-mediated immune response and node cells of to lesions jejunallymph sheep exposed MAP, but with no or paucibacillary lesions, O nected To control the disease, diagnostic tests consisting of small granulomata include incre ased secretion ot tumor necro- must identify the first (heavy shedders) and composed of epithelioid cells Surrounded by many lymphocytes and sis factor (TNF)-O, increased IL-10 (which second (intermediate) groups. Diagnosis in the live animal is hindered by the paradoxi- with few or no bacilli in the lesions suppresses Thl and enhances Th2 cytokine Lepromatous extreme with a strong production), decreased IL-18, and increased cal immune response during various stages Lon- of the disease. Subclinical infection is char humoral immune response and lesions expression of toll-like receptor 9. composed of of accumulations gitudinal studies of experimental infections acterized by a strong cell-mediated but Suggest that antigen-mediated lymphocyte negligible antibody response, reducing macrophages containing large numbers of mycobacteria the usefulness of serologic tests at this stage. Between these extremes are "borderline apoptosis may contribute to the immune dystunction that occurs in Johnes disease." In contrast, cinical disease is characterized forms, which tend to be associated with the aINICAL FINDINGS by a strong humoral immune response and a disease. Most sheep with most severe clinical weak cell-mediated response. During clinical Johne's disease have the multibacillary lesion disease, high numbers of MAP are shed in Sheep In and Goats (lepromatous) with extensive diffuse macro- sheep and goats the disease is manifested the feces, so a definitive test is culture of the phage infiltrate within the intestinal mucosa principaly by emaciation, with a marked organism from feces. and submucosa. In the paucibaclary lesion (tuberculoid) there is a marked lymphocytic difference in condition _between affected animals and their nonaffected cohorts. In Diagnostic Tests and giant cell infiltration of the intestine. In sheep the abrupt cessation of wool growth sheep, the local release ot macrophage and Culture or Detection of Organism can cause decreased staple strength or shed- Bacteriologic Examination. Several proce other lymphocyte-derived the cytokines may and ding of wool. Diarrhea is not as severe or as dures are used to improve the sensitivity of intluence type of intlammatory common as in cattle, but the Teces may be detecting MAP by culture, including immune response It that develops during the elevated soft enough to lose their usual pelleted tormn. decontamination and concentration of the intection. is propOsed that Aftected sheep may be partialy anorexic and organism from Conventional specimens. production of cytokines, such as IL-10, may ose weight for 6 to 12 months belore they MAP culture consists of decontaminating Their Suppresshand response. encourage a Th2-type This, along with a failure to clear die. the teces usually appear normal until the specimen, concentrating the organisms,A terminal stages of the disease when they and inoculating a growth medium.  Bacterial Diseases of the Ruminant Alimentary Tract 569 molecular-based confirmatory test, such as ooki, M. scrofulaceum, and PCR, to detect the MAP marker sequence M. marinum), are major disadvantages, so use of biopsy will though these are not reported in Johnes be restricted to special circumstances, Such IS9O0 is used to confirm positive typically disease and, if necessary, can be distin- as valuable pedigreed animals. after weeks incubation. specimens 6 to 12 The main criteria for guished by amplicon sequencing. The advan- differentiating M. para- age ot PCR is the speed of reporting (hours Serologic Tests tuberculosis trom other mycobacteria are its days)low orletect and high specificity and ability to Serologic tests are usually cheaper and more slow growth and dependence on mycobactin amounts ot DNA. For example, a apid than tecal culture. Those used in cattle for growth. real-time (RT)-PCR was able to detect Fecal culture using a radiometric tech a single copy of MAP IS900 from a range of are nosis, applicable to sheep and goats, but diag- particularly in individual shep, is nique is more sensitive and less expensive issues of cattle and sheep infected with more dificult. The commonly used serologic compared with conventional fecal culture MAP, including ileum, liver, and muscle." tests are the CF test, AGID test, and a number and DNA probes, but a confirmatory test Such as IS900 PCR 15 still required on posi- ne disadvantage both is that molecular tests of commercial ELISAs. In cattle the CF test letect iving and dead organisms, so a has published estimates for sensitivity as tive specimens. The most commonly used that high as 90% for clinical cases. but much automated positive result is possiblefrom animal an lower for subclinical infections, from I1% to radiometric technique was the which was faster and had has ingested and is shedding MAR, but is not BACTEC system, truly infected. Validation of molecular tests 54%. This test is too unreliable for routine slightly higher sensitivity than conventional to detect MAP has also been lacking. plus use in sheep. because of even poorer sensitiv- culture. However, the liquid modified 1ecal samples are a challenge because ol the 12B being phased out presence PCR inhibitors and a large amount ty and specincity, hence, an unacceptably BACTEC medium is because it requires radioisotopes. of trom other tecal high number of reactions. false-positive nonspeciñc DNA micro Despite this, some countries still require a organisms and the host. CF test before the importation otf Johne's Pooled Fecal Samples and Culture. The culture of pooled fecal samples from 50 Subsequently, a direct quantitative qPCR) lor the detection of MAP in ovine PCR sheep and often in cattle, with combination sheep or 25 goats ot a similar age in a tlock to intradermal johnin testing or fecal culture. or herd is a cost-effective means of determin- teces was shown have a sensitivity and The sensituvity and specifhcity ot ELISA are similar to those in cattle, although cross- ing the infection status of a flock or herd. specihcity similar to BACTEC culture, although it was laborious and unsuited for reactions to C pseudotuberculosis ocur, so Pooling samples reduces the number of tecal commercial application." This led to the absorbing sera with those heat-treated organisms does give improved results. In cultures necessary to determine intection, velopment of a high-throughput direct reducing laboratory costs. It is a more highly tecal PCR, which is highly specific. This test, sensitive and specihe tlock test for detection Australia, in a population of sheep with a high prevalence of subclinical intection, the of known as the high-throughput-Johnes AGID OJD compared with serology using the test. The estimated minimum flock (HT-) test, has been validated in sheep and cattle and approved for use as a herd/tlock sensitivity of an absorbed ELISA was 34% to 54% compared with 38% to 56% for the specihcity of pooled culture when used for test in Johne's disease control programs in AGID test. The AGID was much better at surveillance and assurance testing is 99.1%. Australia and New Zealand. The HT-J test infected sheep in low body condi- detecting the and detected only MAP compared with 51 other Surveillance assurance programs in Aus- tion than ELISA, but the latter was supe rior in detecting infected sheep with localized tralia are designed to provide a lock sensitiv- mycobacterial isolates, including hose with ity of 959% at an assumed prevalence of 2% at S900 type lesions or those with small numbers of MAP lower for sequences, and y9% ot samples from unexposed cattle herds and sheep flocks These much cost (around 30% of that tests have also been evaluated and compared in adult sheep culled from severelyY serologic testing). Pooling of samples is pos ere negative (458 of 460 samples from 8 sible because of the large numbers of MAP unexposed cattle herds, 88 of 89 samples affected flocks, with sensitivity and specific- present in the feces of sheep with multibacil- om I unexposed sheep flock). It was also ity evaluated using histopathologie indings lary disease, estimated to be 1.1 x 10 organ reasonably sensitive compared with BACTEC as a reterence. The sensitivity and specihcityY As the culture at of the AGID was 37% and 100%, respectively, isms per gram of feces. analytical the recommended positivef negative cut points (0.001 pg MAP DNA), of sensitivity of similar culture methods has whereas the sensitivity 48%, but its specificity was only 89%. the ELISA was etecting 67 of 111 samples positive on been estimated to 100 CFU/g of feces, the As discussed previously, sheep a poolng rate can be large. culture exposed cattle in and 93 (60.4%) ot in spec- Microscopic examination of Ziehl- 117 samples positive on culture in exposed trum of infection is defined by two widely Neelsen stained smears of teces for the pres- sheep (83.8%). Almost all samples with a differing forms of the disease: a tuberculoid of typical clumps acid-fast high level of MAP DNA were culture positive form, with strong cell-mediated immune ence of bacteria response and lesions characterized by smal has been an attractive culture because the alternative to fecal results are available (97%), whereas only 25% of samples with a low level of DNA were culture positive. Thus granulomata composed of a tew epithelioid with 2 to 3 months scope exists to vary the cut points for the test cells surrounded by a large number of lym- within an hour, compared for culture. However, the sensitivity and depending on the purpose of testing phocytes, and with no or few bacilli in the clinical However, the HT-J test detects a subset of lesions; and a lepromatous form, with a Specihcity is low except in advanced infected animals that overlaps with, but is not strong humoral immune response accompa cases. It may also be dificult to distinguish identical to, those detected by fecal nied with MAP from other acid-fast organisms that are culture by lesions macrophages Tull o mycobacteria. The sensitivities of ELISA andd often present in feces, and with animals that the AGID test in sheep with lepromatous are intermittent shedders it may be necessary Biopsy. Surgical biopsy of the otterminal lesions 86% and to examine smears on several Occasions to ileum and mesenteric lymph node sheep were 100%, respectively, but obtain a positive result. for detection of MAP has been described, only 10% to 50% and 30% in sheep with with histologic examination and bacterio- tuberculoid lesions. Thus there is a close cor- Genetic Probe. Agenetic element unique to logic culture being highly speciic and sensi- relation between serologic response to AGID MAP is an insertion sequence designated as tive. similarly, histopathology of liver biopsy and the pre sence of acid-fast bacilli in the ot samples had a sensitivity of 96% and 100% intestinal tissues, and the diagnosis of tuber IS900. Genetic probes lor the detection IS900 in clinical Specihcity tor detection of types 3b and ac culoid cases remains difficult. samples such teces are as available as commercial kits using the PCR. ileal lesions in aged ewes. Early detection of Nevertheless, the AGID is rapid, inex- pensive, easily available, and technicallyy Other mycobacterial species contain IS900- animals isone advantage with these tech Thus it is useful for like elements in low copy numbers (M. niques. However, the time taken and costs easy to perform.  570 Chapter 8 Diseases of the Alimentary Tract-Ruminant flock-screening programs to identify infected pattern of lesions seen in cases of OJD may severe or mild. Severe lesions consist of age groups of sheep, especially those with be classified into two advanced OJD lesions and shedding the detailed major types, and extensive macrophage granulomata and descriptions of these histopatho mumerous giant cells, with many intracellu- greatest number ot organisms. In goats, the logic changes are available. lar acid-fast bacteria in the smal intestine. specificity of the AGD and absorbed ELISA Bacteremia occurs with MAP infection, tests in an Australian study was 100% and so granulomatous lesions are sometimes 99.8%, respectively, with the ELISA preferred identified in filtering organs Such as the liver, DIFFERENTIAL DIAGNOSIS because of its higher sensitivity. lung, and spleen. No lesions occur in an The characteristic features of infected tetus, but the organism can be iso dinical Johnes Tests of Immunity lated from its viscera and trom the placenta disease include progressive weight loss, and emaciation in a single animal or In vivo tests of cell-mediated immunity group o and uterus. Traditionaly, the most accurate animals within a mob, and chronic diarrhea, included the skin and intravenous joh