Human brucellosis is one of the world's most common zoonoses, with an incidence in certain countries exceeding 10 per 100,000 population, particularly in poor rural settings.
Rarely fatal, but relapse can occur with debilitating and economically devastating effects. It is considered a class B bioterrorist agent, is easily spread by aerosol, and is a significant hazard in microbiology laboratories.
The 4 main human pathogens causing disease are Brucella melitensis, B abortus, B suis, and B canis.
Most cases of brucellosis in Northern Europe and North America are acquired overseas and/or from consuming unpasteurized milk products including cheese.
The disease can affect any organ system and therefore presents in a variety of ways, especially as a prolonged fever of unknown origin, with associated rheumatic features in about 50% of cases. Diagnosis is based on clinical presentation and laboratory tests.
Combination antibiotic therapy is the mainstay of treatment and should be used for prolonged periods to prevent relapse of symptoms. There is disagreement about the optimum treatment regimen.
Small pearly white colonies of Brucella melitensis after prolonged culture on blood agar
From the collection of Dr Nicholas J. Beeching; used with permission