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Providing evidence to improve practice

Individual study: BCG vaccination reduces risk of tuberculosis infection in vaccinated badgers and unvaccinated badger cubs

Published source details

Carter S.P., Chambers M.A., Rushton S.P., Shirley M.D.F., Schuchert P., Pietravalle S., Murray A., Rogers F., Gettinby G., Smith G.C., Delahay R.J., Hewinson R.G. & McDonald R.A. (2012) BCG vaccination reduces risk of tuberculosis infection in vaccinated badgers and unvaccinated badger cubs. PLoS ONE, 7, e49833

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Use vaccination programme Terrestrial Mammal Conservation

A randomized, controlled, before-and-after study in 2006–2009 in an area of mixed woodland and farmland in Gloucestershire, UK (Carter et al. 2012, same experimental set-up as Chambers et al. 2011) found that vaccinating Eurasian badgers Meles meles against tuberculosis reduced the number of animals infected. Three years after vaccination with Bacillus Calmette-Guérin (BCG) began, the number of badgers infected with tuberculosis (119 of 342 tested, 35%) was lower than before vaccination began (156 of 294 tested, 53%). Vaccination reduced the likelihood of individual badgers testing positive for tuberculosis by 54%. Unvaccinated badgers from vaccinated social groups were less likely to have tuberculosis (adults: 35%, cubs: 21% infected) than badgers from unvaccinated social groups (adults: 52%, cubs: 33% infected). Additionally, unvaccinated cubs were 79% less likely to become infected with tuberculosis when at least one third of the adults in their social group were vaccinated. However the probability of an unvaccinated adult having tuberculosis did not change when more group members were vaccinated. From June 2006–October 2009, badgers were caught in baited steel mesh traps, set for two consecutive nights, twice a year at every active sett in a 55 km2 study area. Badgers were tested for tuberculosis using three tests. Social groups were randomly allocated to “vaccinated” or “not vaccinated” treatments. Badgers in vaccination groups were injected with 1 ml of Bacillus Calmette-Guérin (BCG) Danish strain 1331 vaccine once/year.

(Summarised by Andrew Bladon)