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.     

The use of a microagglutination assay for the detection of antibodies to Corynebacterium pseudotuberculosis in naturally infected sheep and goat flocks

Two goat flocks comprising 326 animals and four sheep flocks comprising 343 animals, all with a previously recognized problem of abscesses due to Corynebacterium pseudotuberculosis, were examined for the presence of abscesses and antibody titers to C. pseudotuberculosis as detected by direct microagglutination assay. In sheep there was a strong positive relationship between age and titer (p less than 0.0001). However, the relationship in goats between age and titer could not be determined due to a strong interaction between flock and age. When the relationship between abscesses and titer was examined, it was found that goats with abscesses had higher titers than those that did not (p less than 0.05), whereas there was no difference in titer between sheep with abscesses and those without (p = 0.5753). The sensitivity of the microagglutination test was poor to good for both species (52.3% for goats and 89.7% for sheep). The specificity of the test was fair to poor (64.9% for goats and 21.7% for sheep). Given a disease prevalence of 13.5% for goats and 8.5% for sheep the predictive value of the positive test was very poor (18.9% for goats and 9.6% for sheep) but the predictive value of the negative test was good to excellent (89.7% for goats and 95.8% for sheep). The poor specificity of the test and therefore the positive predictive value may be due in part to the criterion of classification of presence of disease, i.e. presence of an abscess at the time of sampling.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serologic response and lesions in goats experimentally infected with Corynebacterium pseudotuberculosis of caprine and equine origins

Fifteen goat kids were experimentally inoculated with Corynebacterium pseudotuberculosis. Five were given a strain of caprine origin (nitrate-negative biotype) intradermally, 5 were given a strain of equine origin (nitrate-positive biotype) intradermally, and 5 were inoculated intranasally with the caprine-origin strain. Animals were monitored for 127 days. The goats given the inocula intradermally developed abscesses; those given caprine-origin strain had multiple lesions both peripherally and in visceral locations (primarily endothoracic abscesses), whereas those given the equine-origin strain had abscesses only at injection sites and draining nodes. The difference in extent of lesions could be due to biotypic bacterial differences or to the individual strains used. Intranasally inoculated goats did not develop abscesses and were essentially no different from controls. The cranial part of the respiratory tract may not be an important portal of entry for C pseudotuberculosis. Serum samples obtained monthly from all animals were subjected to the synergistic hemolysis-inhibition test, which measures antibodies to the exotoxin of C pseudotuberculosis. Animals with abscesses developed titers within 1 month of inoculation. Animals without abscesses remained seronegative. The synergistic hemolysis-inhibition test may be a reliable diagnostic assay for caseous lymphadenitis in goats.     

Enteritis in sheep, goats and pigs due to Yersinia pseudotuberculosis infection

The features of naturally occurring Yersinia pseudotuberculosis serotype III infections in 16 sheep, one goat and 3 pigs, and Y. pseudotuberculosis serotype I infections in 3 goats, are described. Affected animals usually had diarrhoea and were in poor condition or emaciated. A number were moribund or dead when submitted for necropsy. Thickening of the caecal and colonic mucosa was the only gross lesion attributable to Y. pseudotuberculosis infection, with liver or other visceral abscesses not being seen. Characteristic microabscesses were demonstrated in the intestinal mucosa of 10 sheep, one goat and one pig infected with Y. pseudotuberculosis serotype III and one goat infected with Y. pseudotuberculosis serotype I. Sheep, goats and pigs dosed orally with Y. pseudotuberculosis serotype III, the serotype isolated most commonly from these species, developed intestinal infection. In sheep and pigs, infection was accompanied by diarrhoea. Haematological changes and specific antibodies were elicited in all 3 species in response to infection. Microabscesses were seen in the intestinal mucosa of all experimentally exposed animals. The occurrence of field cases and the results of experimental exposure confirm that Y. pseudotuberculosis serotype III is an enteropathogen of sheep, goats and pigs. The association of Y. pseudotuberculosis serotype I with lesions in a goat, indicates that this bacterium may also be a pathogen of this species. It is concluded that Y. pseudotuberculosis serotype III is an enteric pathogen of a wide range of ungulate species including cattle, buffalo, deer, antelopes, sheep, goats and pigs. Serotypes I and II, while having a more restricted host range, are probably also pathogens of ungulates and, in particular, deer, antelopes and goats.     

Use of a toxoid vaccine to protect goats against intradermal challenge exposure to Corynebacterium pseudotuberculosis

Two groups of male, 9-week-old goats (5 goats/group) were vaccinated subcutaneously with formalized exotoxin of Corynebacterium pseudotuberculosis, with Freund's incomplete adjuvant. Each goat was given 2 vaccinations, 2 weeks apart. At each vaccination, each group 1 goat was given 0.5 ml of toxoid, and each group 2 goat was given 1 ml of toxoid. Twenty days after the 2nd vaccination, vaccinated goats and 5 nonvaccinated 12-week-old goats (controls) were inoculated intradermally (challenge exposed) with live C pseudotuberculosis, monitored for 13 weeks, and euthanatized. At necropsy, 5 of the 10 vaccinated goats did not have C pseudotuberculosis lesions, 3 had abscesses limited to the inoculation site and draining lymph node, and 2 had disseminated bacterial lesions. Of the 5 nonvaccinated controls, 4 had disseminated abscesses and 1 had a single abscess in an internal node. Serologically, 9 of the 10 vaccinated goats developed positive (greater than or equal to 1:8) antibody titers against the exotoxin within 1 week after inoculation; the 10th goat seroconverted 2 weeks after inoculation, whereas control goats required 3 weeks to develop a positive antibody response. Therefore, early during an infection with C pseudotuberculosis, antibodies against the exotoxin may protect a goat against spread of the organism. All goats were injected intradermally before challenge exposure, 10 days after challenge exposure, and at 4, 8, and 12 weeks after challenge exposure with a skin-test reagent composed of fragmented bacterial cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Visceral caseous lymphadenitis in thin ewe syndrome: isolation of Corynebacterium, Staphylococcus, and Moraxella spp from internal abscesses in emaciated ewes

The relationship between the visceral form of caseous lymphadenitis and a chronic debilitating condition of mature sheep designated as the thin ewe syndrome was investigated. Internal abscesses were found during necropsy in 81% of animals with thin ewe syndrome and Corynebacterium pseudotuberculosis (C ovis) was recovered from 86% of the animals with internal abscesses. Other pyogenic bacteria, including C pyogenes, C equi, Staphylococcus epidermis, S aureus, and Pseudomonas aeruginosa were often recovered in association with C pseudotuberculosis. Moraxella sp was recovered in 41% of the animals with internal abscesses. In some abscesses, Moraxella sp was the dominant microorganism isolated and in others, they were outnumbered only by C pseudotuberculosis. Species isolated included M bovis, M osloensis, and M nonliquefaciens. The potential importance of Moraxella sp to the cause and pathogenesis of the thin ewe syndrome is not known. The results of the present study indicate that visceral caseous lymphadenitis is either an important contributing factor to the development of thin ewe syndrome or that the presence of thin ewe syndrome may predispose affected sheep to the development of visceral caseous lymphadenitis. A skin test reagent prepared by sonicating C pseudotuberculosis was of limited value in detecting animals with visceral caseous lymphadenitis. Only 56% of the animals with abscesses caused by C pseudotuberculosis gave positive delayed-type hypersensitivity skin test responses.     

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.     

Microorganisms associated with abscesses of sheep and goats in the south of Iran

A total of 86 abscesses (45 and 41) abscesses of sheep and goats, respectively) were examined for their causal agents; 44 of these abscesses were located subcutaneously, and the remaining 42 were in lungs, livers, intestines, and udders. A total of 23 different types of microorganisms were isolated from 78 abscesses; bacteria were not detected in the remaining eight abscesses. Microorganisms isolated were: species of the genera Corynebacterium, Staphylococcus, and Streptococcus and Pasteurella, Escherichia coli, and other gram-negative rods. Peptostreptococcus anaerobius and Eubacterium tortuosum were isolated in pure culture from one abscess each in goats. Two to four different microorganisms were associated with 25 of the 86 abscesses. It was determined that 11 isolates of Corynebacterium pyogenes, 2 isolates of Pasteurella haemolytica, 1 of P multocida, and 1 of C pseudotuberculosis were lethal to mice. Two of the C pyogenes isolates from subcutaneous spreading abscesses of goats were pathogenic for rabbits; these two isolates produced similar suppurative inflammation in goats experimentally, but did not cause death. As determined by experimental inoculation, goats were more susceptible than sheep to the two isolates. In nature, subcutaneous abscesses of goats associated with C pyogenes were of a more diffusive type which resulted in generalization of the infection and death of the animals. Postmortem examination of ten goats dying of field infection showed the presence of larvae of the warble-fly Przhevalskiana silenus at the site of infection.     

The role of Corynebacterium pseudotuberculosis lung lesions in the transmission of this bacterium to other sheep

SUMMARY: :Five groups of 5 shorn and 5 unshorn caseous lymphadenitis (CLA)-free Merino wether weaners were each placed in feedlot pens with 6 Merino ewes, 2 or more of which had CLA lung lesions but no discharging superficial lesions. The sheep were kept together for 5 months.
Twenty-eight per cent of the shorn weaners and 20% of the unshorn weaners developed antibodies to Corynebacterium pseudotuberculosis. At slaughter, 8% of the shorn weaners and 12% of the unshorn weaners had CLA lesions in either lungs, lymph nodes or both. In the absence of contact with CLA-infected ewes, a control group of 5 shorn and 5 unshorn weaners failed to develop antibodies to C. pseudotuberculosis or CLA lesions in the same period. This showed that sheep with CLA abscesses in the lungs but no discharging superficial abscesses were a source of C. pseudotuberculosis infection to other sheep. Aust Vet J. 64: 261–263     

Prevalence of and carcass condemnation from maedi-visna,paratuberculosis and caseous lymphadenitis in culled sheep from Quebec,Canada

We determined the prevalence of lung and mammary gland lesions associated with maedi-visna (MV) infection, the prevalence of paratuberculosis (PTB), and the prevalence and lesions distribution of caseous lymphadenitis (CL) in culled sheep. Total of 451 ewes and 34 rams were selected randomly from two slaughterhouses in Quebec, Canada. MV serostatus was determined by recombinant ELISA test. PTB diagnosis was based on characteristic histological lesions in the terminal ileum, ileocecal lymph node and/or ileocecal valve and CL by gross detection of abscesses and isolation of Corynebacterium pseudotuberculosis. Seroprevalence of MV was 44% (95% CI: 40, 48). Seropositivity increased with age and was higher in ewes than in rams. The percentages of lung and mammary gland lesions in seropositive sheep were 14 and 40%, respectively, but mammary gland lesions lack specificity. The prevalence of PTB was 3% (95% CI: 2, 5). PTB increased with age and was lower among sheep with abscesses. The prevalence of CL was >/=21% (95% CI: 17, 24). The most-prevalent site of caseous lymphadenitis lesions was the thoracic cavity. The risk of carcass condemnation was significantly associated with region, body score and abscesses. Only the presence of abscesses was associated with an increase in trimming of carcasses.     

Immunisation against ovine caseous lymphadenitis: comparison of Corynebacterium pseudotuberculosis vaccines with and without bacterial cells

Sheep were immunised with Corynebacterium pseudotuberculosis vaccines prepared from cell-free toxoid or from toxoid with formalin-killed cells of C pseudotuberculosis added. Resistance of sheep to infection was tested 6 months after immunisation by inoculation with caseous lymphadenitis pus. The outcome was assessed 3 months later by slaughter and inspection of the sheep for lesions of caseous lymphadenitis. immunised sheep were adequately protected against infection as shown by a significant reduction in the number of sheep exhibiting lesions compared with control sheep, and by fewer abscesses in affected vaccinated sheep than in affected control sheep. The protective potency of the vaccines was not improved by the inclusion of cells of C pseudotuberculosis.     

Impact of Corynebacterium pseudotuberculosis infection on serologic surveillance for Johne's disease in goats.

False-positive results on serologic assays for Mycobacterium avium subsp. paratuberculosis (MAP) are believed to occur due to cross-reacting antibody produced by Corynebacterium pseudotuberculosis (C. pstb) infection in goats. This issue of compromised specificity was evaluated by testing 771 adult goats from 10 Midwestern goat herds in 2004. Assays for MAP infection included radiometric fecal culture and 2 enzyme-linked immunosorbent assays (ELISAs); ELISA-positive samples were tested by agar gel immunodiffusion (AGID). A synergistic hemolysin inhibition assay (SHI) was used to detect C. pstb antibody. Four infection status categories were evaluated. Category 1 goats (free of both MAP and C. pstb infection) tested negative on all MAP fecal cultures and SHI tests. Five of 181 goats were positive in both ELISAs, and 2 more were positive in ELISA-1 only. For Category 2 (MAP infected; no C. pstb infection), all animals were SHI negative. Six goats were fecal culture positive and strongly positive in both ELISAs; 2 more goats were positive only in ELISA-1. For Category 3 (C. pstb infected or vaccinated; no history of MAP infection), all fecal cultures were negative and 91% were SHI test-positive. In this population, only 2 goats were positive in both MAP ELISAs, while 84 additional goats were test-positive only on ELISA-1. In the absence of C. pstb infection, both ELISAs performed comparably, but when C. pstb infection was present the performance of ELISA-1 was significantly perturbed. Use of the ELISA-2 for goats is an effective and efficient method for Johne's disease surveillance in any goat herd.     

Comparison of an interferon-gamma to a phospholipase D enzyme-linked immunosorbent assay for diagnosis of Corynebacterium pseudotuberculosis infection in experimentally infected goats

The optimal method of control of caseous lymphadenitis of goats caused by Corynebacterium pseudotuberculosis is eradication of infection by identification and removal of infected carrier animals. The objective of this study was to compare detection of C. pseudotuberculosis experimentally infected goats using a commercially available bovine interferon-gamma (IFN-gamma) whole blood enzyme-linked immunosorbent assay (ELISA) to serological response to a recombinant phospholipase D (PLD) ELISA. The tests were assessed repeatedly over 1 year in three infected and three non-infected goats. Using a IFN-gamma optical density cut-off at 0.10 as positive under the conditions used, the test accurately detected C. pseudotuberculosis experimentally infected goats over a 363 day period with a reliability of 89.2% and non-infected goats with a reliability of 97.1%. Using a cut-off value of the mean for negative samples plus two standard deviations, the PLD ELISA detected C. pseudotuberculosis experimentally infected goats over this period with a reliability of 81.0% and non-infected goats with a reliability of 97.0%. The PLD ELISA was however more predictive than the IFN-gamma ELISA of the presence of lesions observed at postmortem examination of infected goats.     

Enzyme immunoassay for surveillance of Q fever

An enzyme-linked immunosorbent assay (ELISA) was developed to monitor antibodies against Coxiella burnetii among animal populations used in research and teaching facilities. Various antigenic components of C burnetii prepared from phase I and phase II whole cells and commercially available antigens were evaluated. A trichloroacetic acid extract was selected for routine use. There was a linear relationship between the transformed absorbance readings of the ELISA results and microagglutination (MA) titers. Comparison between positive or negative results of the MA test and ELISA gave 98.6% concordance. Using the MA test as the standard, ELISA results were 97.8% sensitive and 100% specific. The efficacy of ELISA was evaluated by testing ruminants with known histories of C burnetii infection. Antibody prevalence was 0 in 117 sheep with no history of C burnetii infection, 22% in 145 naturally infected sheep used for research, and 53% in 115 sheep used for vaccine field trials. Forty-eight percent of 120 dairy cows and 52% of 79 goats from endemically infected herds were seropositive. These results indicate that ELISA should be the test of choice for mass screening and surveillance of animals when Q fever is a suspected biohazard.     

The role of goats as reservoir hosts for bovine herpes virus 1 under field conditions

Bovine herpesvirus 1 (BoHV1) is the cause of economically significant viral infections in cattle. Respiratory symptoms associated with the infection are known as Infectious Bovine Rhinotracheitis (IBR). Sheep and goats are less sensitive to the infection although their role in inter-species viral transmission under field conditions is subject to controversy. The objective of this study was to investigate seroprevalence of BoHV1 infections in cattle, sheep, and goats raised together for at least a year. Blood serum samples were taken from 226 cattle, 1.053 sheep, and 277 goats from 17 small- to medium-scale farms. BoHV1-specific antibody presence and titers were determined using virus neutralization test. In total, 73 of the 226 cattle (32.3%) were seropositive. The infection was detected in 13 of the 17 farms. Infection rates ranged from 5.8 to 88.8%. Only one of the 1053 sheep (0.09%) was seropositive. However, 58 of the 277 (20.9%) goats were seropositive. Goat samples taken from 8 of the 17 farms were seropositive with infection rates ranging from 17 to 38.9%. Statistical analysis showed a significant correlation in infection rates between cattle and goats but not sheep. These results suggest that goats may be more sensitive to the BHV1 infection than sheep and the role of goats as possible reservoirs for BoHV1 in the control and eradication of BHV1 in cattle should be considered in future studies.

     

Host associated polymorphisms in the Corynebacterium pseudotuberculosis rpoB gene sequence

Corynebacterium pseudotuberculosis is a widespread facultative intracellular pathogen that causes caseous lymphadenitis disease in sheep and goats, and generates cutaneous abscesses and granulomas in horses and cattle. Although some genes have been studied for diagnostic and phylogenetic analysis within the genus Corynebacterium, at subspecies level the pathogen has been poorly analyzed. The aim of this study was to characterize C. pseudotuberculosis strains isolated from domestic animals, through the sequencing of a hypervariable rpoB gene segment. As result, there were identified host associated rpoB polymorphisms in strains infecting sheep, goats and horses from Chile. These differences suggest the existence of bacterial genotypes, in which the nucleotide similarity values were ranging from 98.8 to 99.8%. In conclusion, the analysis of polymorphisms in the partial rpoB sequence can be used as a diagnostic tool that differentiates C. pseudotuberculosis strains at subspecies level.     

Brucellae through the food chain: the role of sheep, goats and springbok (Antidorcus marsupialis) as sources of human infections in Namibia

A confirmed case of human brucellosis motivated an investigation into the potential source of infection in Namibia. Since domestic animals are principal sources of Brucella infection in humans, 1692 serum samples were screened from sheep, goats and cattle from 4 presumably at-risk farms and 900 springbok (Antidorcas marsupialis) serum samples from 29 mixed farming units for Brucella antibodies by the Rose-Bengal test (RBT) and positive cases confirmed by complement fixation test (CFT). To assess the prevalence of human brucellosis, 137 abattoir employees were tested for Brucella antibodies using the standard tube agglutination test (STAT) and by enzyme linked immunosorbent assay (ELISA). Cattle and sheep from all 4 farms were negative by RBT and CFT but 2 of the 4 farms (Ba and C) had 26/42 and 12/285 seropositive goats, respectively. Post mortem examination of seropositive goats revealed no gross pathological lesions typical of brucellosis except enlarged mesenteric and iliac lymph nodes seen in a single buck. Culture for brucellae from organs of seropositive animals was negative. None of the wildlife sera tested positive by either RBT or CFT. Interviews revealed that besides the case that prompted the investigation, a family and another person from other farms with confirmed brucellosis shared a common history of consumption of unpasteurised goat milk, home-made goat cheese and coffee with raw milk and prior contact with goats, suggesting goats as the likely source of infection. All 137 abattoir employees tested negative by STAT, but 3 were positive by ELISA. The 3 abattoir workers were clinically normal and lacked historical connections with clinical cases. Although goats are often associated with B. melitensis, these studies could not explicitly implicate this species owing to cross-reactivity with B. abortus, which can also infect goats. Nevertheless, these data reinforce the need for a better National Control Programme for brucellosis in Namibia.     

Immunisation against ovine caseous lymphadenitis: correlation between Corynebacterium pseudotuberculosis toxoid content and protective efficacy in combined clostridial-corynebacterial vaccines

Groups of sheep were dosed with vaccines containing Corynebacterium pseudotuberculosis toxoid combined in varying amounts with 5 clostridial antigens. Resistance of the sheep to infection with C pseudotuberculosis was tested at 1, 6 and 12 months after vaccination by infection with pus from ovine lymph glands actively infected with C pseudotuberculosis. The outcome was assessed 3 months after challenge by slaughter and inspection of the sheep for caseous lymphadenitis lesions. Protection was demonstrated by a significant reduction in the proportion of immunised sheep exhibiting lesions compared with control sheep, and by fewer abscesses in affected immunised sheep than in affected control sheep. A positive correlation was found between amount of C pseudotuberculosis toxoid administered and degree of protection obtained. Chromatographically-purified toxoid induced essentially the same protection, suggesting that anti-toxic immunity is the major factor in protection.     

Differential antibody responses to Corynebacterium pseudotuberculosis in sheep with naturally acquired caseous lymphadenitis

Enzyme-linked immunosorbent assays (ELISA) with Corynebacterium pseudotuberculosis cell wall and bacteria-free supernatant with exotoxin preparations as antigens, and hemolysis inhibition tests were used to detect antibodies in the sera of adult range sheep with naturally acquired caseous lymphadenitis (CL). The extent and severity of lesions were quantitated on the basis of a lesion score, derived from an examination of the carcass (peripheral lymphoid tissue) and viscera (including internal lymphoid tissue) at the time of slaughter. The overall prevalence of C pseudotuberculosis-positive CL lesions in 104 sheep was 31.7%. The cell wall ELISA detected antibodies in 96.9% (32/33) of sheep with C pseudotuberculosis-positive CL lesions. The exotoxin ELISA detected antibodies in 84.8% (28/33) of positive sheep in the same group. Both ELISA resulted in a high number of apparent false-positives, with 64.7% and 49.2%, respectively, positive optical density (OD) values in sheep with no gross CL lesions and no apparent C pseudotuberculosis infection. There was no significant relationship between the extent of lesion development (lesion score) and OD values in both cell wall (r = 0.472) and exotoxin (r = 0.464) ELISA. Similarly, there was no significant relationship between the titer of antitoxin antibodies, as measured by the hemolysis inhibition test, and the extent of disease. These investigations indicate that those ELISA that use crude C pseudotuberculosis antigens are of questionable utility in the field, where C pseudotuberculosis infection is endemic in many sheep populations. Furthermore, these studies suggest that antibodies that are reactive with components of C pseudotuberculosis and that develop in response to infection may have little impact on the recovery of the host.     

Corynebacterium pseudotuberculosis infection in goats. III. The influence of age

Serological examinations for Gorynebacterium pseudotuberculosis in-fection were carried out in 14 known positive herds and in 1 herd that had beeni recently established through purchase of animals from different herds. Serum samples were collected sequentially on up to 4 occasions from animals during their first year of life. In most herds, these animals were examined clinically for superficial swellings once or twice during the same period.The adult goats in 8 infected herds were examined both clinically and serologically. Age distribution was similar in each of these herds. All serum samples were examined for antibodies against Gorynebac-terium pseudotuberculosis in both the bacterial agglutination test (BAT) and the hemolysis inhibition test (HIT).The proportion of kids which were seropositive in both tests de-creased to zero at 4 months of age. At the age of 11–12 months, the proportion of seropositive animals was about 50 % in the BAT and 30 % in the HIT.When examined when housed for the winter at the age of about 8 months (mean age), the prevalence of animals with superficial swellings was 7 %. At the age of about 1 year (mean age), 29 % of the examined animals had such lesions. In the recently established herd, only a few of the yearlings were seropositive.Titre values in BAT and HIT increased until 6 years of age. Anti-body titre values were significantly lower in yearlings than in older goats in both tests, P < 0.005. No significant difference in the propor-tion of goats with superficial swellings was seen at the different ages.