TABLE 2.

Pathological and microbiological findings following challenge of calves with M. bovis

Vaccine groupProportion of animals with:Mean lung scoreaMean LN scorebMean no. of lesioned LN per animalcProportion of animals with cultures positive for M. bovisProportion of thoracic lymph node cultures positive for M. bovisMean bacterial count for thoracic lymph nodesd
Lung lesionsLN lesions
Nonvaccinated10/1010/102.40 ± 0.313.70 ± 0.15a3.00 ± 0.26a10/1031/402.898 ± 0.168
BCG at birth0/10e0/10e,f0e,f0e,f0e,f6/1012/40e,f0.893 ± 0.062e,f
BCG at 6 weeks0/9e1/9e0e,f0.11e ± 0.260.22 ± 0.22e,f8/914/36e1.279 ± 0.136e
BCG at birth and at 6 weeks3/10e4/10e0.90 ± 0.46e0.50 ± 0.22e1.20 ± 0.49e9/1021/40e1.463 ± 0.157e
  • a Lung lesion score: 0, no lesions; 1, 1 to 9 lesions; 2, 10 to 29 lesions; 3, 30 to 99 lesions; 4, 100 to 199 lesions.

  • b Lymph node (LN) lesion score for the most severely affected lymph node per animal: 0, no lesions; 1, 1 to 19 small lesions (1- to 4-mm diameter); 2, ≥20 small lesions; 3, medium size lesion (5- to 9-mm diameter); 4, large lesion (≥10-mm diameter).

  • c Mean number of lymph nodes with macroscopic tuberculous lesions per animal.

  • d Mean bacterial count, log10 CFU/gram of tissue (when no bacteria were isolated, a count of 0.699 log10 CFU/g was recorded).

  • e Significantly less than for the nonvaccinated group (P<0.05).

  • f Significantly less than for the group vaccinated with BCG at birth and at 6 weeks (P>0.05).