A serodiagnostic test (ELISA) for defecting antibodies to Sarcoptes sc
abiei in the sera of pigs was evaluated, The ELISA results from 221 sp
ecific pathogen-free pigs of three different age categories were used
to establish a cut-off value for the assay, Background optical density
values differed significantly between the three groups, the sows havi
ng the highest values, The mean + 3 sd of their values was chosen as t
he cut-off, Four farrow-to-finish herds of pigs with sarcoptic mange w
ere investigated, Skin scrapings were taken from each animal for the d
emonstration of S scabiei and their sera were assayed for the presence
of antibodies to the mite. AII the herds had active infections with S
scabiei and antibodies to S scabiei were found in a significant numbe
r of the animals sampled, The sensitivity and specificity of the ELISA
were 87.8 and 99.5 per cent, respectively, employing clinical diagnos
is as the gold standard, A higher sensitivity (100 per cent), but a lo
wer specificity (32.8 per cent) was obtained when the results of skin
scrapings were used as the gold standard.