Human brucellosis: a classical infectious disease with persistent diagnostic challenges.

Although brucellosis and its means of transmission were discovered over 100 years ago, the disease remains a world-wide problem, predominantly so in developing countries. Brucellosis has been an emerging disease since the discovery of B. melitensis by Bruce in 1887. The diagnosis of brucellosis can be challenging since its presentation can affect any body organ and system and can overlap that of a wide spectrum of infectious and non-infectious diseases. Routine biochemical and hematological laboratory tests also overlap with those of many other diseases. Thus, brucella-specific tests are the most helpful in the diagnosis. Tests ranging from culture to serodiagnostic tests such as slide or tube agglutination and its indirect Coombs extension, enzyme-linked immunosorbent assay, and indirect fluorescent assays, to the recent molecular techniques such as polymerase chain reaction are available. Knowledge about the advantages, disadvantages, and limitations of these tests are essential for the proper interpretation of their results, in relation to the history and clinical presentation of the individual being investigated. This update article addresses these and other issues related to this classical infectious disease that remains a diagnostic challenge, especially to the unaware.