The pathogenesis of tuberculosis in the calf

Epidemiology and pathogenesis ofMycobacferium bowisinfection of red deer (Cervus elaphus) in New Zealand

“…bovis have also been recovered from a number ofcattle without gross lesions in the respiratory tract (Neill et al, 1988a(Neill et al, , 1988b(Neill et al, , and 1989, suggesting that bacilli may have been shed by the NPT. The significant association between infected sites in the head and thoracic cavity suggests that after primary tonsillar infection there is rapid haematogenous dissemination to the lungs, as suggested with calves (Edwards,1937;White and Minett, 1941) and other species in which the lung is a predilection site ofinfection (Lug1on, 1997). The presence ofgrey subpleural pulmonary nodules was significantly related to the presence oflungwonn only, but their occurrence presents a diagnostic dilemma as these lesions can be caused by both lungworm and M. bovis infection.…”

“…These findings highlight the importance of OPT culture at necropsy for increasing the sensitivity ofdiagnosis, particularly when lesions are not found elsewhere. The absence oflesions in tonsils suggests that they, in common with other lymphoepithelial sites, such as the NPT or Peyer's patch, often remain free ofgrossly visible lesions when infected with mycobacteria, unless challenged by large numbers ofbacilli (White and Minett, 1941;Glover, 1941;Payne and Rankin, 1961). The NPT was infected in four cases, in three of which it was likely to have been the primary site ofinfection.…”

Experimental infection of badgers (Meles meles) withMycobacterium bovis

“…As it may result in acute, rapidly fatal, tuberculous pneumonia, this route is unsuited to the study of the immune response over a period of many months, which appears to be the time course of natural infection in both captive badgers (Little, Naylor & Wilesmith, 1982) and wild badgers (Anon, 1984). The use of intratracheal inoculation of tubercle bacilli in a fluid menstruum has been reported in cattle to produce only localized lesions in pulmonary lymph nodes (White & Minett, 1941). This method appeared suited to production of a localized chronic pulmonary tuberculosis in the badger.…”

Mucosa‐associated lymphoid tissues as sites for uptake, carriage and excretion of tubercle bacilli and other pathogenic mycobacteria

“…Ulceration of the Peyer's patches and mucosal lymphoid aggregates in the large intestine apparently occurs only under conditions of extreme bacillary challenge. This may occur when large oral inocula are delivered or when heavily contaminated sputum is swallowed 10 , 47 , 58 , 65 , 66 , 67 . Thus, in humans, high rates of gastrointestinal tuberculosis are often a consequence of active pulmonary and laryngeal disease.…”

“…Involvement of the oropharyngeal tonsil and Peyer's patch in the acquisition of infection following feeding of M. bovis-contaminated milk to calves has been shown clearly by White and Minett. 47 However, large doses of bacilli are necessary to establish gross lesions at these sites. In another series of experiments by Payne and Rankin, 48 calves given large doses of Mycobacterium avium ssp.…”