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  • Author or Editor: W. Ray Waters x
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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)

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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

Abstract

Objective—To evaluate immune responses induced by administration of Mycoplasma hyopneumoniae bacterin to pigs.

Animals—60 healthy 7- to 10-day-old cross-bred boars.

Procedure—Pigs were assigned to 1 of 4 pig groups (15 pigs/group): vaccinated, challenged; vaccinated, nonchallenged; nonvaccinated, challenged; nonvaccinated, nonchallenged. Vaccinated pigs received IM injections of a mycoplasma bacterin on days 0 and 14, whereas nonvaccinated pigs received saline (0.9% NaCl) solution. Pigs in the challenged groups were inoculated intratracheally with M hyopneumoniae on day 42. Pigs were euthanatized and necropsied 41, 44, 48, and 70 days after the first vaccination, and proportion of lung surface with pneumonic lesions was determined. Percentage of lymphocyte subpopulations and number of interferon-γ (IFN-γ) secreting lymphocytes in blood and tissues, cytokine and antibody concentrations in bronchoalveolar lavage (BAL) fluid, and serum antibody concentrations were determined.

Results—Vaccination against and infection with M hyopneumoniae induced a local mucosal immune response in the respiratory tract of pigs. Proportion of lung surface with pneumonic lesions in vaccinated challenged pigs was reduced on day 70, compared with nonvaccinated challenged pigs. Vaccination stimulated the production of M hyopneumoniae-specific IFN-γ secreting blood lymphocytes. Tumor necrosis factor-α concentration in BAL fluid on day 70 was increased in nonvaccinated challenged pigs, compared with vaccinated challenged pigs.

Conclusions and Clinical Relevance—Vaccination against M hyopneumoniae induced local, mucosal, humoral, and cellular immune responses. Moreover, vaccination reduced the severity of lung lesions in challenged pigs, suggesting that mucosal antibodies, mediation of the inflammatory response, and cellmediated immune responses are important for control of mycoplasmal pneumonia in pigs. (Am J Vet Res 2000;61:1384–1389)

Full access
in American Journal of Veterinary Research