Maria E. Negron, Rebekah Tiller, Grishma A. Kharod
Facultative, intracellular, gram-negative coccobacilli; known human pathogens include Brucella abortus, B. melitensis, B. suis, and B. canis.
Most commonly through consumption of unpasteurized dairy products or undercooked meat from infected animals and direct contact with infected animals, especially those that have recently given birth. Since wildlife can be reservoirs for Brucella spp., hunting can be a risk for exposure as well. Brucella can enter the body via skin wounds, mucous membranes, or inhalation. Person-to-person transmission is rare.
High-risk regions include the Mediterranean Basin, South and Central America, Eastern Europe, Asia, Africa, and the Middle East. In these areas, brucellosis is primarily enzootic in cattle, sheep, and goat populations, as well as feral swine.
Incubation period is usually 2–4 weeks (range, 5 days to 5 months). Initial presentation is nonspecific, including fever, muscle aches, fatigue, headache, and night sweats. Focal infections are common and can affect most organs in the body.
Blood culture is the diagnostic gold standard, but is not always positive. If culture of blood, bone marrow, or other clinical specimen is performed, the laboratory must be informed that Brucella is suspected, as the culture takes longer to grow and laboratory personnel require additional personnel protective equipment when handling cultures. A serum agglutination test is the most common serologic approach, but other serology assays (including ELISA) and PCR have been used to make a diagnosis. Brucellosis is a nationally notifiable disease.
Doxycycline, rifampin, trimethoprim-sulfamethoxazole, fluoroquinolones, aminoglycosides, and other agents have been used in various combinations for a minimum of 6–8 weeks. If bacteria localize in organs and tissues and cause focal infection, surgical drainage could be indicated. Late diagnosis or inappropriate therapy can result in chronic disease or relapse.
Avoid unpasteurized dairy products and undercooked meat. Wear protective equipment when dressing or butchering wild animals potentially infected with Brucella spp. In clinical microbiology laboratories, if Brucella spp. is suspected, culture isolates should be handled under BSL-3 conditions.
Al Dahouk S, Nockler K. Implications of laboratory diagnosis on brucellosis therapy. Expert Rev Anti Infect Ther. 2011 Jul;9(7):833–45.
Ariza J, Bosilkovski M, Cascio A, Colmenero JD, Corbel MJ, Falagas ME, et al. Perspectives for the treatment of brucellosis in the 21st century: the Ioannina recommendations. PLoS Med. 2007 Dec;4(12):e317.
Arnow PM, Smaron M, Ormiste V. Brucellosis in a group of travelers to Spain. JAMA. 1984 Jan 27;251(4):505–7.
Memish ZA, Balkhy HH. Brucellosis and international travel. J Travel Med. 2004 Jan-Feb;11(1):49–55.
Pappas G, Papadimitriou P, Akritidis N, Christou L, Tsianos EV. The new global map of human brucellosis. Lancet Infect Dis. 2006 Feb;6(2):91–9.
Rhodes HM, Williams DN, Hansen GT. Invasive human brucellosis infection in travelers to and immigrants from the Horn of Africa related to the consumption of raw camel milk. Travel Med Infect Dis. 2016 May-Jun;14(3):255–60.
Yousefi-Nooraie R, Mortaz-Hejri S, Mehrani M, Sadeghipour P. Antibiotics for treating human brucellosis. Cochrane Database Syst Rev. 2012;10:Cd007179.