SAT is the most commonly used serology in endemic areas. An agglutination titre greater than 1:160 is considered significant in nonendemic areas and greater than 1:320 in endemic areas.Due to the similarity of the O polysaccharide of Brucella to that of various other Gram-negative bacteria (e.g. Francisella tularensis, Escherichia coli, Salmonella urbana, Yersinia enterocolitica, Vibrio cholerae, and Stenotrophomonas maltophilia), the appearance of cross-reactions of class M immunoglobulins may occur. The inability to diagnose B. canis by SAT due to lack of cross-reaction is another drawback. False-negative SAT may be caused by the presence of blocking antibodies (the prozone phenomenon) in the α2-globulin (IgA) and in the α-globulin (IgG) fractions.Dipstick assays are new and promising, based on the binding of Brucella IgM antibodies, and are simple, accurate, and rapid. ELISA typically uses cytoplasmic proteins as antigens. It measures IgM, IgG, and IgA with  better sensitivity and specificity than the SAT in most recent comparative studies. The commercial Brucellacapt test, a single-step immunocapture assay for the detection of total anti-Brucella antibodies, is an increasingly used adjunctive test when resources permit. PCR is fast and should be specific. Many varieties of PCR have been developed (e.g. nested PCR, realtime PCR, and PCR-ELISA) and found to have superior specificity and sensitivity in detecting both primary infection and relapse after treatment.
Brucellosis ring testing of milk and cream, and testing of cattle to be slaughtered ended on 1 April 1999. Monitoring continues through testing at auction markets, through standard disease-reporting procedures, and through  testing of cattle being qualified for export to countries other than the United States. China
An outbreak infecting humans took place in Lanzhou in 2020 after the Lanzhou Biopharmaceutical Plant, which was involved in vaccine production, accidentally pumped out the bacteria into the atmosphere in exhaust air due to use of expired disinfectant. The outbreak affected over 6,000 people. Europe
Malta
Until the early 20th century, the disease was endemic in Malta to the point of it being referred to as "Maltese fever". Since 2005, due to a strict regimen of certification of milk animals and widespread use of pasteurization, the illness has been eradicated from Malta. Republic of Ireland
Ireland was declared free of brucellosis on 1 July 2009. The disease had troubled the countrys farmers and veterinarians for several decades. The Irish government submitted an application to the European Commission, which verified that Ireland had been liberated. Brendan Smith, Irelands then Minister for Agriculture, Food and the Marine, said the elimination of brucellosis was "a landmark in the history of disease eradication in Ireland". Irelands Department of Agriculture, Food and the Marine intends to reduce its brucellosis eradication programme now that eradication has been confirmed. UK
Mainland Britain has been free of brucellosis since 1979, although there have been episodic re-introductions since.