Tests for brucellosis are categorized into clinical methods and diagnostic tests. 1. Clinical methods: Brucellosis should be suspected in the presence of compatible signs and symptoms (fever, malaise, night sweats, and arthralgia) in the presence of relevant epidemiologic exposures. The diagnosis of brucellosis can be confirmed based on any of the following findings: Brucella bacteria from blood, body fluids, or tissue cultures; Brucella antibody titers measured in serum samples from the recovery phase are 4 times or more the titers measured in the acute phase (with at least 2 weeks between sample collections). A presumptive diagnosis of brucellosis may be made based on any of the following findings: Serum samples collected after the onset of symptoms have a total Brucella antibody titer of ≥1:160 by standardized tube agglutination tests; Brucella DNA is detected by PCR on clinical samples. 2. Diagnostic tests: For patients with suspected brucellosis, blood culture and serologic testing should be performed. Laboratory tests such as complete blood count and liver function tests should also be performed. For patients with negative blood cultures and serologic tests, further investigations should be carried out according to the clinical manifestations of each individual. For example, patients with signs and symptoms of osteoarthropathy require synovial fluid analysis and imaging. Patients with neurologic manifestations require a lumbar puncture; this maneuver is usually not diagnostic but may help differentiate brucellosis from other etiologies. If the above evaluation is not abnormal, a bone marrow biopsy sample is required for culture and histopathologic examination. If bone marrow evaluation is not diagnostic and there is evidence of liver involvement (based on liver function tests and/or imaging), a liver biopsy is required.