A critical reappraisal of transmission routes for bovine TB in cattle

The great badgers and bovine TB debate

“…In attributing source of TB in herd breakdowns, the protocols (Zuckerman 1980;Krebs 1997) fail to recognize the seemingly non-reactor and noninfectious ' undisclosed source ', so that badgers get blamed by default. Other wildlife or domestic animal or human sources are improbable (Hancox 1999), and the ' due to badgers ' breakdowns were originally given as ' unknown ' source, e.g. 69 % in Cornwall 1972-78 or 32 % in Ulster currently even with a fully computerized cattle database.…”

“…Lastly, since it is claimed that both cattle and badger TB is of some 80 % respiratory origin it is hard to see how transmission could occur in either direction ; mutual avoidance ! The misunderstanding arises through failing to recognize that lung TB in badgers is secondary, TB often first being shown to be of dietary origin in the submandibular lymph nodes under the tongue (Little et al 1982;Anderson & Trewhella 1985;Pritchard et al 1986;Hancox 1995Hancox , 1997Hancox , 1999. The distinction between primary and secondary lung infection is clear (Francis 1947(Francis , 1958, but uncritical studies of badger lesions have perpetuated the error (Krebs 1997;Gallagher & Clifton-Hadley 2000;O'Boyle 2000).…”

Latency and the control of bovine TB in man and other animals

“…Indeed it is still claimed that since transmission is not understood, it is not possible to initiate controls via husbandry risks based on robust science. [1][2][3] Comparison with TB schemes in man are valuable, and one of the key factors being overlooked would seem to be the long incubation period of TB, which dictates the measures available as well as the need for a targeted approach to high-risk groups for the most cost-effective results. This is well documented for human TB in the USA with full recognition that cases may not become skin test reactors until after 2-12 weeks after infection.…”