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Abstract

Objective—To determine whether Mycobacterium bovis can be transmitted from experimentally infected deer to uninfected in-contact deer.

Animals—Twenty-three 6-month-old white-tailed deer.

Procedure—On day 0, M bovis (2 × 108 colony-forming units) was administered by intratonsillar instillation to 8 deer; 3 control deer received saline (0.9% NaCl) solution. Eight in-contact deer were comingled with inoculated deer from day 21. On day 120, inoculated deer were euthanatized and necropsied. On day 180, 4 in-contact deer were euthanatized, and 4 new incontact deer were introduced. On day 360, all in-contact deer were euthanatized. Rectal, oral, and nasal swab specimens and samples of hay, pelleted feed, water, and feces were collected for bacteriologic culture. Tissue specimens were also collected at necropsy for bacteriologic culture and histologic analysis.

Results—On day 90, inoculated and in-contact deer developed delayed-type hypersensitivity (DTH) reactions to purified protein derivative of M bovis. Similarly, new in-contact deer developed DTH reactions by 100 days of contact with original in-contact deer. Tuberculous lesions in in-contact deer were most commonly detected in lungs and tracheobronchial and medial retropharyngeal lymph nodes. Mycobacterium bovis was isolated from nasal secretions and saliva from inoculated and in-contact deer, urine and feces from in-contact deer, and hay and pelleted feed.

Conclusions and Clinical RelevanceMycobacterium bovis is efficiently transmitted from experimentally infected deer to uninfected in-contact deer through nasal secretions, saliva, or contaminated feed. Wildlife management practices that result in unnatural gatherings of deer may enhance both direct and indirect transmission of M bovis. (Am J Vet Res 2001;62:692–696)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate the infection of calves with Mycobacterium bovis through oral exposure and transmission of M bovis from experimentally infected white-tailed deer to uninfected cattle through indirect contact.

Animals—24 11-month-old, white-tailed deer and 28 6-month-old, crossbred calves.

Procedure—In the oral exposure experiment, doses of 4.3 × 106 CFUs (high dose) or 5 × 103 CFUs (low dose) of M bovis were each administered orally to 4 calves; as positive controls, 2 calves received M bovis (1.7 × 105 CFUs) via tonsillar instillation. Calves were euthanatized and examined 133 days after exposure. Deer-to-cattle transmission was assessed in 2 phases (involving 9 uninfected calves and 12 deer each); deer were inoculated with 4 × 105 CFUs (phase I) or 7 × 105 CFUs (phase II) of M Bovis. Calves and deer exchanged pens (phase I; 90 days' duration) or calves received uneaten feed from deer pens (phase II; 140 days' duration) daily. At completion, animals were euthanatized and tissues were collected for bacteriologic culture and histologic examination.

Results—In the low- and high-dose groups, 3 of 4 calves and 1 of 4 calves developed tuberculosis, respectively. In phases I and II, 9 of 9 calves and 4 of 9 calves developed tuberculosis, respectively.

Conclusions and Clinical Relevance—Results indicated that experimentally infected deer can transmit M bovis to cattle through sharing of feed. In areas where tuberculosis is endemic in free-ranging white-tailed deer, management practices to prevent access of wildlife to feed intended for livestock should be implemented. (Am J Vet Res 2004;65:1483–1489)

Full access
in American Journal of Veterinary Research

Summary

Protein expression profiles of 10 isolates of Mycobacterium paratuberculosis, M avium 18 (formerly M paratuberculosis 18), and 1 isolate each of M avium serotype 2, M avium serotype 8, and M bovis BCG were examined. Protein expression profiles of M paratuberculosis and M avium were similar. However, two-dimensional gel analysis of [35S]methionine-labeled cellular proteins resolved 4 proteins, with molecular mass of 28,000, 32,000, 32,000, and 42,000 daltons, which were expressed in greater amounts in M paratuberculosis than in M avium. Two proteins, with molecular mass of 43,000 and 60,000 daltons, were identified, which were expressed in greater amounts in M avium than in M paratuberculosis. Immuno (western)-blot analysis, using antiserum from 2 cows clinically infected with M paratuberculosis as the primary antibodies, suggested that the 42,000- dalton protein may be specific for M paratuberculosis.

Comparison of protein expression profiles may be useful as a tool for differentiating isolates of < M > paratuberculosis. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of [35S]methionine-labeled extracellular proteins revealed variability among the isolates. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of [35S]methionine-labeled cellular proteins divided the M paratuberculosis isolates into 2 groups on the basis of a difference in the amount of expression of a 28,000-dalton protein. This information may be useful in epidemiologic studies.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To examine the temporal development of tuberculous lesions in cattle inoculated with Mycobacterium bovis.

Animals

15 mature crossbred cows obtained from a herd with no history of M bovis infection.

Procedure

Inoculation of cattle was done by intratonsilar instillation of 1.48 × 105 to 5.4 × 107 colony-forming units of M bovis strain 2045T. At 3 to 4 hours, 4 weeks, 6 weeks, and 8 weeks after inoculation, tissues were examined for gross and microscopic lesions and processed for isolation of M bovis.

Results

Retropharyngeal lymph nodes from cattle examined 4 weeks after inoculation contained microgranulomas consisting of aggregates of macrophages with few neutrophils. Retropharyngeal lymph nodes from all cattle examined 6 and 8 weeks after inoculation contained multiple, large, coalescing granulomas consisting of central areas of necrosis with mild fibrosis, numerous macrophages, lymphocytes, plasma cells, multinucleated giant cells, and neutrophils. Three of 8 cattle examined 6 or 8 weeks after inoculation had lesions in nonretropharyngeal sites with morphologic characteristics similar to that seen in retropharyngeal lymph node granulomas from cattle examined 4 weeks after inoculation.

Conclusion

Granulomas can develop in draining lymph nodes of cattle in as little as 4 weeks after inoculation via intratonsilar instillation of M bovis. Intralesional morphologic changes between 4 and 6 weeks after inoculation indicate an increase in cellular chemotaxis and differentiation. Dissemination of bacteria to distant sites most likely was by lymphatic and hematogenous routes after establishment of the primary infection in retropharyngeal lymph nodes. (Am J Vet Res 1999;60:310–315)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine prevalence of tuberculosis caused by infection with Mycobacterium bovis in cervids on privately owned ranches in northeastern lower Michigan.

Design—Epidemiologic survey.

Animals—Cervids on 96 privately owned ranches.

Procedures—A combination of slaughter and skin tuberculin testing was used to collect data. Infection with M bovis was confirmed by use of standard necropsy and bacteriologic culture techniques.

Results—Cervids with tuberculosis were detected on 1 of the 96 ranches. The apparent prevalence of tuberculosis in cervids from the 96 ranches was 1.1 cases/100 cervids (21 cases/1,867 cervids tested). For the ranch with infected cervids, prevalence of infection with M bovis was 12.1 cases/100 cervids (21 cases/174 cervids tested). No obvious gross lesions were seen in 8 of 21 white-tailed deer and 1 coyote with culture-confirmed M bovis infection.

Conclusions and Clinical Relevance—The lack of visible lesions in a substantial proportion of infected animals should be taken into consideration in studies involving detection and prevalence of tuberculosis. (J Am Vet Med Assoc 2002;220:656–659)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the distribution of lesions and extent of tissues infected with Mycobacterium bovis in a captive population of white-tailed deer.

Design—Cross-sectional study.

Animals—116 captive white-tailed deer.

Procedure—Deer were euthanatized, and postmortem examinations were performed. Tissues with gross lesions suggestive of tuberculosis were collected for microscopic analysis and bacteriologic culture. Tissues from the head, thorax, and abdomen of deer with no gross lesions were pooled for bacteriologic culture. Tonsillar, nasal, oral, and rectal swab specimens, fecal samples, and samples of hay and pelleted feed, soil around feeding sites, and water from 2 natural ponds were collected for bacteriologic culture.

ResultsMycobacterium bovis was isolated from 14 of 116 (12%) deer; however, only 9 of 14 had lesions consistent with tuberculosis. Most commonly affected tissues included the medial retropharyngeal lymph node and lung. Five of 14 tuberculous deer had no gross lesions; however, M bovis was isolated from pooled tissue specimens from the heads of each of these deer. Bacteriologic culture of tonsillar swab specimens from 2 of the infected deer yielded M bovis. Mean (± SEM) age of tuberculous deer was 2.5 ± 0.3 years (range, 0.5 to 6 years). Mycobacterium bovis was not isolated from feed, soil, water, or fecal samples.

Conclusions and Clinical Relevance—Examination of hunter-killed white-tailed deer for tuberculosis commonly includes only the lymph nodes of the head. Results of such examinations may underestimate disease prevalence by as much as 57%. Such discrepancy should be considered when estimating disease prevalence. (J Am Vet Med Assoc 2000;216:1921–1924)

Full access
in Journal of the American Veterinary Medical Association

Abstract

A study to determine and compare the sensitivity of the caudal fold tuberculin test (cft) and a commercial γ-interferon (γ-ifn) assay for diagnosis of bovine tuberculosis was conducted. A dairy herd with approximately a third of the cattle infected with Mycobacterium bovis was chosen for this study. All cattle from this herd were slaughtered, and tissue specimens for bacteriologic culturing and histologic examination were collected. Results of the cft and γ-ifn assay were compared with results of bacteriologic culturing and histologic examination to determine test sensitivity. Results were analyzed, using each of the following 4 standards to classify cattle as infected: positive test result by bacteriologic culturing only; histologic examination only; bacteriologic culturing and histologic examination; and bacteriologic culturing or histologic examination. Sensitivity of the cft ranged from 80.4 to 84.4%, depending on the standard of comparison. Sensitivity of the γ-ifn assay ranged from 55.4 to 97.1%, depending on the standard of comparison and on the method of interpretation. The cft was significantly (P < 0.001) more sensitive than the γ-ifn assay for diagnosis of bovine tuberculosis when the γ-ifn assay was conducted and interpreted as instructed by the manufacturer. Maximum overall sensitivity was achieved when results of the cft and γ-ifn assay were interpreted in parallel.

Free access
in American Journal of Veterinary Research