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Serological tests for badgers bTB
Journal
Veterinary Microbiology
- Vol 86, Iss 3 , 1 May 2002,
pp183-189
Authors
M. A. Chambers, W. A. Pressling, C. L. Cheeseman, R. S.
Clifton-Hadley and R. G. Hewinson from the Veterinary Laboratories Agency
and the Central Science Laboratory.
Abstract
In the UK there has been a sharp rise in the incidence of
btb since the early 1990s and the badger has been identified as an
important wildlife reservoir for this infection. Infected badgers can
excrete btb, putting other badgers and cattle at risk of becoming
infected. Vaccination has been proposed as an approach to reducing the
excretion of btb by tuberculous badgers. In order to evaluate the
efficacy of a badger vaccine it will be necessary to accurately
determine the number of badgers excreting btb without removing them for post-mortem evaluation. The
existing live tests for btb in the badger (culture, indirect ELISA, Western
blot) have not been assessed for their ability to detect badgers
excreting btb. Over the past 18 years, badgers from 31 social groups
have been trapped and sampled in a study area of the Cotswold
escarpment. We have examined the serological responses of 128 badgers
trapped between 1985 and 1998 from social groups where btb infection was
endemic. These responses were compared with culture from faeces, urine,
tracheal aspirates and bite wound swabs taken from these animals while
alive. ELISA was found to be more sensitive than Western blot in
detecting badgers excreting btb. The majority of
culture-positive badgers excreted btb intermittently over the period of study.
As a result, there was only a 27.5% chance of sampling a badger for
culture when it was excreting btb. In contrast, a positive ELISA result
correctly predicted 68.2% of badgers with a history of excreting btb. In
the absence of alternative live tests for the badger, the Brock Test indirect
ELISA appears to be more valuable than culture for measuring the effect of
vaccination on reducing the number of badgers at risk of transmitting
btb.
Keywords
Mycobacterium bovis; Badger; Serology; Infection
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