Diagnosis of Brucella abortus
Specimens that can be submitted for diagnostic testing: serum, aborted fetus, fetal membranes, placenta, fetal lung, liver and abomasal contents, uterine discharge or vaginal mucus, milk from lactating animals and semen. There are a wide variety of diagnostic tests available for the diagnosis of Brucella abortus; the tests discussed here are the most commonly used and most widely available.

Organism isolation

The Brucella abortus organism can be isolated from fetal lymph nodes, placenta, milk, vaginal mucus, uterine exudate or semen. A nucleic acid probe assay is being developed for easier identification of Brucella abortus.

Serological tests

These tests detect antibodies present in serum, milk, whey, vaginal mucus and seminal plasma.  The serological diagnosis is considered unreliable when performed during the period of 2 to 3 weeks before and after abortion or calving.

  • Serum agglutination - considered the standard test at this time.  The serum agglutination test will detect non-specific antibodies as well as those that are specific for Brucella abortus infection and vaccination.
  • Rose Bengal test (buffered plate antigen or card test). This is a rapid and simple screening test that is useful for detecting early infections.

Complement Fixation Test

This test has good specificity and is the most definitive test at this point in time aside for bacterial isolation.

ELISA (Enzyme Linked Immunosorbent Assay)

This test has been useful during eradication programs after vaccination has ceased and is used for screening or as a supplemental test to the complement fixation test. The ELISA test has superior sensitivity and reliably detects true negative results.

Milk Ring Test (antibody detection in milk)

This test is a satisfactory and inexpensive test used for surveillance of dairy herds for brucellosis.

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