Prevalence of caseous lymphadenitis and usage of caseous lymphadenitis vaccines in sheep flocks

OBJECTIVE: To estimate the prevalence of caseous lymphadenitis (CLA), determine the current usage of vaccines against CLA and to measure the effectiveness of these vaccines on sheep farms. DESIGN AND POPULATION: A survey was undertaken on 223 sheep flocks in New South Wales, Victoria and Western Australia. METHOD: The prevalence of CLA was measured by conventional inspection techniques at abattoirs in lines of sheep that could be traced back to a farm. Managers of the flocks were sent a questionnaire about their vaccine practices, management practices and knowledge of CLA. RESULTS: The average prevalence of CLA in adult sheep in these flocks was 26% and varied from 20% in Western Australia to 29% in New South Wales. About 43% of sheep producers used CLA vaccines; only 12% used them as recommended. Awareness of CLA was highest in Western Australia. More producers would use CLA vaccine if they knew the prevalence of CLA in their flock and producers obtained most information about CLA from vaccine resellers. CONCLUSIONS: Only 10 to 15% of producers are currently achieving effective CLA control through the use of recommended CLA vaccination programs. In Western Australian flocks more than 25% of effectively vaccinated ewes will be sent to abattoirs in the 2 to 3 years after this study. However, large decreases in the prevalence of CLA can be achieved by about 70% of producers by either making adjustments to their vaccination programs or buying a vaccine with a CLA component. Two or three key facts on effective CLA vaccination could be made available at the point of sale of vaccines and from abattoirs that reported the prevalence of CLA to farmers.     

Prevalence and distribution of caseous lymphadenitis in feral goats

A total of 2,920 feral goats from pastoral areas of Western Australia were examined and the prevalence of caseous lymphadenitis was estimated to be 7.8 +/- 0.9% in goats presented for slaughter. Head, body and visceral lesions were present in 49.3%, 46.7% and 12.3% of affected goats, respectively. A comparison with previously reported data from sheep has been made and significant differences are discussed. Lung lesions were relatively uncommon in goats, whereas the distribution of carcase lesions was similar between the species. Multiple lesions appear to be less common in goats than in sheep.     

Serodiagnosis of inapparent caseous lymphadenitis in goats and sheep, using the synergistic hemolysis-inhibition test

The synergistic hemolysis-inhibition (SHI) test, a serologic test for the detection of infection with Corynebacterium pseudotuberculosis, was applied to serum samples from 196 goats and 76 sheep, including animals both with and without C pseudotuberculosis abscesses. Fifty-one of 52 (98%) goats and 27 of 28 (96%) sheep with abscesses caused by C pseudotuberculosis had seropositive titers. Seropositivity continued on subsequent samplings, even after superficial lesions were completely healed. The SHI test may detect subclinically infected animals, as well as animals with clinically recognizable lesions. Of the animals without abscesses, 53 of 186 (28%) goats and 4 of 41 (10%) sheep were seropositive. Either the SHI test is lacking in specificity or these titers are a reflection of a past or a current infection without any grossly visible abscesses.     

Serum proteins of normal goats and goats with caseous lymphadenitis.

Values for total serum proteins and relative percentages of albumin, alpha 1-globulin, alpha 2-globulin, beta-globulin, and gamma-globulin were determined for the goat. These normal values were compared with those obtained for goats infected with Corynebacterium pseudotuberculosis. Goats chronically infected with C pseudotuberculosis show significantly higher total serum protein values than normal goats, apparently due to increased gamma-globulins. This higher protein value is also associated with a decrease in serum alpha 2- and beta-globulins.     

A comparison of four serological tests for the diagnosis of caseous lymphadenitis in sheep and goats

A double antibody sandwich ELISA (ELISA A) developed for the detection of Corynebacterium pseudotuberculosis infection in sheep and goats was modified to improve its sensitivity. To establish the sensitivity and specificity of this modified ELISA (ELISA B), sera from 183 sheep and 186 goats were tested using ELISAs A and B. Comparison was also made with two further ELISAs (C and D) developed in Australia that, respectively, detect antibodies to cell wall antigens or toxin.ELISA B had the best performance of the four tests. Its specificity was 98+/-1% for goats and 99+/-1% sheep. Its sensitivity was 94+/-3% for goats and 79+/-5% for sheep. ELISA B will now be tested for use in caseous lymphadenitis eradication and control programmes in The Netherlands. It will also be used in experimental studies of CL in Scotland.     

Characterization of lectin-binding lymphocytes in goats with caseous lymphadenitis

Numbers of lymphoid cells bearing markers for peanut agglutinin, wheat germ agglutinin, and anti-immunoglobulin G in healthy goats and in goats with caseous lymphadenitis were determined by use of immunofluorescent techniques. Results indicated that, when compared with healthy goats, diseased goats had normal numbers of anti-immunoglobulin G-positive cells (B cells), had significantly reduced numbers of peanut agglutinin-positive cells (T cells), and had fewer cells with receptor sites for Lens culinaris agglutinin and concanavalin A. Compared with healthy goats, numbers of peanut agglutinin-positive cells in goats with caseous lymphadenitis indicated that the goats may have had a compromised cell-mediated immunity.     

Abscesses and caseous lymphadenitis in goats in tropical semi-arid north-east Brazil

Summary This study reports the incidence of abscesses in relation toCorynebacterium pseudotuberculosis infection in goats in north-east Brazil. Among 656 goats examined periodically over almost two years 41·6% were found with superficially palpable abscesses. Most of the infected areas were in the anterior half of the body in front of the pre-scapular region; the inguinal region formed the other prominent area. Among 486 dead or slaughtered goats, 56 (11·5%) revealed abscesses in the internal organs. Lungs and epididymis were affected most, liver, spleen, udder and lateropharyngeal nodes were next in order and kidneys and mediastinal nodes were least affected. Thus the overall incidence of external and internal abscesses was 28·8%; of all the abscesses 27·7% were due toC. pseudotuberculosis and the rest due to infections ofCorynebacterium pyogenes and several species of streptococci or staphylococci. The growth ofC. pseudotuberculosis-infected and non-infected goats was of the same order and it seems that caseous lymphadentitis is not the cause of much financial loss in north-east Brazil but in view of its high incidence remedial measures should be considered necessary in regions where the goat meat industry is likely to become more intensive and important.

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Resumen Este estudio informa sobre la incidencia de abscesos en cabras del nordeste de Brasil. Se examinaron 656 cabras periódicamente durante dos a?os, de las cuales 41·6% se encontraron con abscesos superficiales palpables. Las áreas infectadas correspondieron a la mitad anterior del cuerpo, frente a la región pre-escapular y a la región inguinal. De 486 cabras muertas o faenadas, 56 (11·5%) revelaron abscesos en los órganos internos. De estos, los mas afectados, en orden descendente fueron: pulmones, epididimos, hígado, bazo, ubre, nódulos linfáticos faríngeos, ri?ones y nódulos linfáticos mediastínicos. La incidencia general de abscesos externos e internos fue de 28·8%. De todos los abscesos 27·7% se debieron aCorynebacterium pseudotuberculosis y el resto aC. pyogenes y a especies deStreptococcus y Staphylococcus. El crecimiento de cabras infectadas y no infectadas conC. pseudotuberculosis fue similar, lo que sugiere que la linfadenitis caseosa no ocasiona muchas pérdidas económicas en el nordeste de Brasil pero en vista de su alta incidencia medidas de control deben ser consideradas en regiones donde la industria de carne caprina pueda llegar a ser mas intensiva e importance.

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Résumé Parmi 656 caprins examinés périodiquement pendant presque deux ans, 41,6 p. 100 ontété trouvés porteurs d'abcès palpables superficiels. Dans la plupart des cas, la zone infectée se trouvait dans la moitié antérieure du corps, à l'avant de la région pré-scapulaire. La région inguinale constituait la deuxième zone la plus infectée. Sur 486 animaux morts ou abattus 56 (11,5 p. 100) ont montré des abcès internes affectant en premier lieu les poumons et l'épididyme. Le foie, la rate la vessie, les ganglions pharyngienslatéraux venaient ensuite dans l'ordre. Les ganglions rénaux et médiastinaux étaient les moins affectés. La incidence des abcesses externes et internes a étè de 28,8 p. 100. Globalement, 27,7 p. 100 des abcès étaient dus àC. pseudotuberculosis. le reste àC. pyogenes et à quelques espèces de staphylocoques et streptocoques. la croissance des caprins infectés ou non parC. pseudotuberculosis était à peu près identique et il semble que la lymphadénite caséeuse n'entra?ne pas beaucoup de pertes financières dans le Nord-Est brésilien mais étant donné sa fréquence élevée, des mesures curatives devraient être considérées comme nécessaires dans les régions où l'industrie de la viande de chèvre a des chances de devenir plus intensive et plus importante.

     

Synergistic hemolysis-inhibition titers associated with caseous lymphadenitis in a slaughterhouse survey of goats and sheep in Northeastern Brazil

A survey of caseous lymphadenitis was conducted at a goat and sheep slaughterhouse in Northeastern Brazil One hundred and fifty-eight goats and 43 sheep were examined for the presence of abscesses, with bacterial culturing of purulent material to define the etiological agent. Blood was collected simultaneously for determination of serological titer via the synergistic hemolysis-inhibition test which measures antibodies to an exotoxin of Corynebacterium pseudotuberculosis. Thirteen and nine-tenths percent of the goats had abscesses, with a high proportion having mediastinal or pulmonary lesions (9.5%). Two sheep had abscesses, both with internal organ involvement. Corynebacterium pseudotuberculosis was the most frequently isolated organism. Of 22 goats with abscesses, 20 were positive via the synergistic hemolysis-inhibition test. Both of the sheep with abscesses had positive synergistic hemolysis-inhibition titers. The proportion of serological reactors was greater than the proportion of animals with abscesses. The synergistic hemolysis-inhibition test may be detecting subclinically infected animals.     

Double-antibody sandwich enzyme-linked immunosorbent assay and immunoblot analysis used for control of caseous lymphadenitis in goats and sheep.

A double-antibody sandwich ELISA for detection of antibodies directed against the exotoxin of Corynebacterium pseudotuberculosis, the cause of caseous lymphadenitis (CL) in small ruminants, was developed. A concentrated exotoxin was used. For interpretation of ELISA results, these sera were tested: sequentially obtained sera of C pseudotuberculosis-inoculated goats and sheep that were monitored for 68 weeks; sequentially obtained sera from 80 goats of 3 flocks with CL; sera from 652 goats of 7 flocks without CL; sera from 160 sheep of 4 flocks without CL; and 2,265 caprine and 208 ovine sera submitted for diagnostic testing. Data regarding the infection status and history of 10,454 of the 23,302 animals were collected after testing; most of these were goats that had been part of a CL control program. Specificity and sensitivity of the ELISA were nearly 100%. Subsequently, 31,978 animals from which no data on infection status of flocks had been collected were then tested. It was concluded that the ELISA is a useful diagnostic test for CL eradication programs. Sera with doubtful or inconclusive ELISA results were examined by use of immunoblot analysis. Proteins from C pseudotuberculosis culture supernatant were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and blotted onto nitrocellulose. Six proteins with molecular mass of 68, 65, 39, 38, 31, and 29 kDa reacted with sera from goats and sheep with experimentally induced or naturally acquired infection. Immunoblot analysis was valuable in classifying sera with doubtful or inconclusive results by ELISA.     

Immunophenotype of pulmonary cellular infiltrates in sheep with visceral caseous lymphadenitis

Pulmonary lesions associated with Corynebacterium ovis were analyzed with an indirect immunoperoxidase staining technique using monoclonal antibodies. The predominant cells in abscess walls and surrounding lung parenchyma were large macrophages which expressed major histocompatibility complex (MHC) class II molecules on their surfaces. T lymphocytes were prominent in the same sites in the naturally occurring lesions, and SBU-T4-positive ("helper/inducer") cells were the major subset of lymphocytes (mean T4/T8 ratio = 3.5). B lymphocytes and granulocytes comprised minor populations of infiltrating cells. These results implicate activated macrophages and MHC class II-restricted T lymphocytes in the pathogenesis of established C. ovis infections in sheep.     

A serological investigation of caseous lymphadenitis in four flocks of sheep

A double antibody sandwich ELISA developed by ID-DLO, Lelystad to detect Corynebacterium pseudotuberculosis infection was used on 329 sheep from four pedigree Suffolk flocks in which clinical cases of caseous lymphadenitis (CLA) had occurred. At subsequent necropsy, typical CLA lesions were seen in 133 sheep, and the diagnosis was confirmed on culture. Lesions were most commonly seen in lungs (n = 46), parotid lymph nodes (n = 44), prescapular lymph nodes (n = 38) and mediastinal lymph nodes (n = 31). The sensitivity of the ELISA test for detecting culture-positive sheep was 0.88, while the specificity of the test was 0.55. The antibody ELISA detected 87.5 per cent of sheep that had CLA lesions restricted to internal organs only. It was concluded that the ELISA test has a valuable role in detecting sheep with both clinical and subclinical CLA.     

Clinicopathological investigation on caseous lymphadenitis in local breed sheep in Algeria

This study was carried out of 4,419 animals raised in an extensive system on local breed sheep of the Tiaret region during 2 years (2010–2011) to determine some clinical and pathological aspects associated to caseous lymphadenitis (CL). Clinical examination revealed a prevalence rate of 5.7 %. CL prevalence rate was significantly higher in females (6 %) than in males (4.8 %). The most affected superficial lymph nodes were mandibular lymph nodes (46.1 %). Gross examination of 1,679 carcasses of sheep at the abattoir revealed the presence of abscesses on 250 carcasses (14.9 %). Out of 105 cases showing lesions of CL, Corynebacterium pseudotuberculosis (53.6 %) was isolated as mixed infection with Staphylococcus aureus (43 %) and Escherechia coli (17.9 %). CL prevalence was significantly higher in adult than in young sheep and in female than in male ones. Visceral form of CL was associated to “thin ewe syndrome” responsible for significant economic losses in Algeria.     

Abscess disease, caseous lymphadenitis, and pulmonary adenomatosis in imported sheep

The occurrence of abscess disease, caseous lymphadenitis, and pulmonary adenomatosis in sheep in Denmark is reported for the first time. Subcutaneous abscesses were observed in imported 4- to 5-month-old lambs of the Lacaune breed 10 days after arrival in Denmark. Abscesses were mostly located in the head, neck and shoulder regions close to the regional lymph nodes. Bacteriological examinations revealed growth of Staphylococcus aureus ssp. anaerobius in all animals with subcutaneously located abscesses containing a viscous white-yellow odourless mass. In addition, Corynebacterium pseudotuberculosis was isolated from abscesses in one animal and lesions consistent with pulmonary adenomatosis were found in four animals.     

The effects of caseous lymphadenitis on wool production and bodyweight in young sheep

Two hundred Merino wether hoggets were used to examine the effect of Corynebacterium pseudotuberculosis infection (caseous lymphadenitis) on wool production and bodyweight. Sheep which were challenged with C. pseudotuberculosis (artificially infected) and not vaccinated against this disease produced 0.20 kg less clean wool than unchallenged controls during the following 12 months. The incidence of sheep with lesions in the group that was vaccinated prior to challenge was 55% lower than in unvaccinated challenged sheep but their wool production was not significantly different from either the controls or the unvaccinated challenged sheep. Vaccinated sheep were also heavier than unvaccinated sheep 12 months after challenge. These results indicate that caseous lymphadenitis infection may reduce wool production.