In preparation of a national paratuberculosis guideline, which was implemented recently, a validation study was performed including four commercial ELISA tests.The tests are based on different Map antigens, a protoplasmic antigen (test A), a whole cell antigen (test B), a cell wall antigen (LAM, test C) and a protoplasmic antigen of a Mycobacterium avium subspecies (test D). Two tests include an absorption step of the samples with M. phlei (test A and B) and two tests are also approved for milk samples (test A and C). Blood serum was collected from 286 dairy cattle from four farms considered free of paratuberculosis (negative panel) and from 110 cows shown to be infected with Map by at least one positive result of the cultivation of faeces and/or up to nine organ samples (positive panel). The positive panel included clinically and sub-clinically diseased animals. Blood, milk, faecal and organ samples of the positive panel were collected at the same day. Milk samples were tested from 115 of the negative and 44 of the positive animals.The relation of antibody detection to shedding of Map, to the extent of gross pathological lesions and to clinical disease was calculated for tests A, B and C.The following characteristics were determined for the four tests:

	Sensitivity (%) Blood serum /milk	Specificity (%) Blood serum /milk
Test A	53.6 / 54.5	99.9 / 98.3
Test B	55.5 / -	94.8 / -
Test C	70.0 / 54.5	76.6 / 88.7
Test D	40.0 / -	94.8 / -

A strong positive relation of antibody detection to the actual shedding state was determined for test A and B. Antibody detection was more often positive in animals with medium to large gross pathological lesions, and in animals with clinical disease.In the national paratuberculosis guideline, the use of serological tests with a specificity of more than 99 % is recommended.