Brucella ovis serology

Brucella ovis serology

Species:           Ovine

Specimen:       10mL serum, 1mL semen

Container:       Red top or gel tube, sterile pottle

Collection protocol:  Venepuncture, semen collection

Special handling/shipping requirements:  Ship chilled

General information about the disease:

Brucella ovis is a bacterial infection of sheep producing clinical or subclinical disease characterised by genital lesions in rams, and placentitis in ewes.

General information about when this test is indicated:

If epididymal lesions are palpated in sheep an investigation of the B. ovis status of the ram flock should be undertaken. Annual palpation and serum sampling of B. ovis free accredited flocks is a requirement of the B. ovis scheme.

The cold complement fixation test (CFT) is most commonly used screening test and a serum sample is required. Doubling dilutions from 1:4 to 1:128 are tested.  If positive CFT results occur management of B ovis infection is required, see below.

B. ovis infection management

For further clarification of B. ovis disease status, gel diffusion (GD) tests on the positive CFT tests are one possibility. This test has a high specificity and a positive GD test confirms B. ovis infection. For additional evidence of infection, semen culture of serologically positive rams could be an additional step. 

In flocks where B. ovis has been detected using CFT and/or GD, it is recommended to test all the sera negative to the CFT using the B. ovis ELISA. This test has high sensitivity and will identify potentially infected rams earlier than either the CFT or GD.

Rams positive to the ELISA could be removed and culled at this point. If farmers insist on a re-test ensure these rams are isolated and tested again 30 days later.  Separate the rams into smaller isolated sub-groups to more easily manage the disease if additional infected rams are discovered.

A month later bleed the rams again. Request the ELISA test for earlier detection of positive reactors.  If all are negative this would rank as the first clear test. Wait 60 days and bleed again, requesting the CFT. If all negative at the 2nd test the flock is now accredited.

Shortcuts and earlier bleeding may lead to misdiagnosing infected animals and poses risks. 

Comparison with other related tests:

For further confirmation of infection, culture of semen samples for B ovis is possible. Collect a fresh sample of semen into a sterile container by electroejaculation and submit chilled to the laboratory.

Brucella ovis Flock Accreditation Scheme Guidelines