Brucellosis is a global zoonotic infection secondary to any of the four Brucella spp. that infect humans. It can be focal or systemic, but has a particular affinity for the musculoskeletal system.
Brucellosis occurs worldwide but is particularly prevalent in Mediterranean regions, Middle East, South Asia, and Central and South America 2. Risk in these countries is partly attributed to ineffective public and domestic animal health services.
Patients present typically with fever, which can be undulating and last for 2-3 weeks. Arthralgia, myalgia and back pain are also common 5. Brucellosis may affect any system and so signs and symptoms are heterogeneous. Please see neurobrucellosis for manifestations of central nervous system infection.
Due to the insidious onset of disease, brucellosis presents in both acute and chronic forms. A variety of methods to detect IgM and/or IgG antibodies have been proposed, with some conflict in the literature regarding which is optimal for diagnosis. The Rose Bengal test, serum agglutination test, Coombs test, lateral flow immunochromatography assay, a fluorescence polarization assay, indirect ELISA assays, and the immunocapture Brucellacapt test may be used independently or in combination to confirm Brucella infection 6.
Brucella spp. are gram-negative coccobacilli, which are mostly spread animal-to-human via unpasteurised dairy products. There are a number of species that act as primary hosts to infect humans as secondary hosts. There are four main species that infect humans 1-4:
- Brucella melitensis (camel, sheep),
- Brucella suis (pigs),
- Brucella abortus (cattle),
- Brucella canis (dogs).
Rarely, the more recently discovered fifth and sixth species B. ceti and B. pinnipediae - found in marine mammals - have been isolated in the context of neurobrucellosis. The CDC has classified the abortus, canis and suis Brucella species as "select agents" due to their potential to be aerosolized for bioterrorism purposes.
Brucellosis may affect any body part and may be focal or systemic, but it has an affinity for infecting the spine:
- musculoskeletal manifestations 1,2
- CNS manifestations (neurobrucellosis) 3
- abdominal manifestations 4,5
- thoracic manifestations
- urogenital manifestations 5
- epididymo-orchitis (10%)
History and etymology
Brucella species are eponymously named in honor of the early investigatory work into disease pathogenesis performed by Scottish pathologist and microbiologist David Bruce, who was born in Melbourne, Australia.
Of note, B. abortus is so named as it causes spontaneous abortion in the third trimester in cattle 7.
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- 2. Pourbagher A, Pourbagher MA, Savas L et-al. Epidemiologic, clinical, and imaging findings in brucellosis patients with osteoarticular involvement. AJR Am J Roentgenol. 2006;187 (4): 873-80. doi:10.2214/AJR.05.1088 - Pubmed citation
- 3. Al-Sous MW, Bohlega S, Al-Kawi MZ et-al. Neurobrucellosis: clinical and neuroimaging correlation. AJNR Am J Neuroradiol. 2004;25 (3): 395-401. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 4. Al-Nakshabandi NA. The spectrum of imaging findings of brucellosis: a pictorial essay. Can Assoc Radiol J. 2012;63 (1): 5-11. doi:10.1016/j.carj.2010.09.011 - Pubmed citation
- 5. Dean AS, Crump L, Greter H et-al. Clinical manifestations of human brucellosis: a systematic review and meta-analysis. PLoS Negl Trop Dis. 2012;6 (12): e1929. doi:10.1371/journal.pntd.0001929 - Free text at pubmed - Pubmed citation
- 6. Díaz R, Casanova A, Ariza J, Moriyón I. The Rose Bengal Test in human brucellosis: a neglected test for the diagnosis of a neglected disease. (2011) PLoS neglected tropical diseases. 5 (4): e950. doi:10.1371/journal.pntd.0000950 - Pubmed
- 7. Khan MZ, Zahoor M. An Overview of Brucellosis in Cattle and Humans, and its Serological and Molecular Diagnosis in Control Strategies. (2018) Tropical medicine and infectious disease. doi:10.3390/tropicalmed3020065 - Pubmed