Abstract :
The application of a test and cull policy to control caseous lymphadenitis (CLA) in a commercial
hill flock in Northern Scotland is described. A commercially available ELISA test kit
(ELITEST CLA ELISA, Hyphen, France) was employed on blood samples taken at approximately
three monthly intervals between November 2007 and August 2009. Following each
round of testing all animals identified as seropositive or diagnosed as CLA-positive by bacteriology
were culled. Additional hygiene and management measures aimed at reducing
the likelihood of disease transmission were also encouraged in the flock. Initial testing in
November 2007 identified a CLA seroprevalence of 10% (n = 1010). Following the described
test-and-cull protocol and a controlled reduction in flock size the seroprevalence was
reduced to 0.4% (n = 538) by August 2009. The flock is still monitored by regular palpation
of external lymph nodes and bacteriologial examination of any purulent discharge. No
external CLA lesions were diagnosed in the flock by clinical examination from July 2008
to date, however in May 2009 sub-clinical CLA was confirmed by post mortem examination
in one ewe which had tested positive serologically. The role and potential benefits of
serological testing as a tool in CLA eradication are discussed.
