Antibodies to M. paratuberculosis are produced by animals in the latter stages of the infection. These antibodies can be detected in serum samples by a variety of techniques; we perform ELISA and AGID assya. The ELISA is available for cattle and goats. The sensitivity (percentage of M. paratuberculosis-infected animals that test positive) of both of these assays is higher in animals with more advanced infections. The specificity (percent of animals free of Johne's disease that test negative) of the assays is approximately 99.5%. False-positive results occur less than once out of every 200 positive tests.
These serological assays cannot be done on animals that have been vaccinated for Johne's disease as this will cause false-positive test results.
All submissions are subject to a $4.00 accession fee. All samples submitted at the same time by a single veterinariain from a single owner/facility constitutes an accession.
Serum (1 to 2 ml) is required for this assay. Serum collected from a clotted blood sample and placed in a leak-proof plastic container is preferred. Serum separator tubes shipped after centrifugation are acceptable. A fee ($0.50/tube) will be charged for blood samples requiring centrifugation after arrival at the laboratory.
Overnight or second day UPS/FedEx delivery on cold packs is recommended. The samples should be shipped to arrive Monday - Friday, 8 am to 4 pm. Overnight mail is also acceptable.
The shipping address is:
Johne's Testing Center
School of Veterinary Medicine, Room 4230
2015 Linden Drive West
Madison, WI 53706-1102
| Accession fee (per accession) | $ 4.00 |
| Cattle: ELISA (per sample) | 6.00 |
| Elk & Llamas: ELISA (per sample) | 10.00 |
| Other ruminants: AGID (per sample) | 10.00 |
| Centrifugation, if necessary (per sample) | .50 |
Results are reported as positive, negative, or suspect based on established
interpretation criteria. In addition, a numerical value from 0 to 100, the S/P
(sample/positive ration), is reported. This number is a measure of the amount of antibody
to M. paratuberculosis in the serum sample. In general, higher levels of serum antibody
indicate more advanced M. paratuberculosis infections and suggest that clinical signs of
Johne's disease in the animal will begin soon, if they haven't already. Results are
provided within 4 working days of receiving the sample, and, on request, will be sent by
fax at no extra charge.
For more information call the Johne's Testing Center:
608-26-JOHNE (608-265-6463).
