Review of clinical and laboratory features of human brucellosis

Abstract

Infection with Brucella spp. continues to pose a human health risk globally despite strides in eradicating the disease from domestic animals. Brucellosis has been an emerging disease since the discovery of Brucella melitensis by Sir David Bruce in 1887. Although many countries have eradicated B. abortus from cattle, in some areas B. melitensis and B. suis have emerged as causes of this infection in cattle, leading to human infections. Currently B. melitensis remains the principal cause of human brucellosis worldwide including India. The recent isolation of distinct strains of Brucella from marine mammals as well as humans is an indicator of an emerging zoonotic disease. Brucellosis in endemic and non-endemic regions remains a diagnostic puzzle due to misleading non-specific manifestations and increasing unusual presentations. Fewer than 10% of human cases of brucellosis may be clinically recognized and treated or reported. Routine serological surveillance is not practiced even in Brucella - endemic countries and we suggest that this should be a part of laboratory testing coupled with a high index of clinical suspicion to improve the level of case detection. The screening of family members of index cases of acute brucellosis in an endemic area should be undertaken to pick up additional unrecognised cases. Rapid and reliable, sensitive and specific, easy to perform and automated detection systems for Brucella spp. are urgently needed to allow early diagnosis and adequate antibiotic therapy in time to decrease morbidity / mortality. The history of travel to endemic countries along with exposure to animals and exotic foods are usually critical to making the clinical diagnosis. Laboratory testing is indispensable for diagnosis. Therefore alertness of clinician and close collaboration with microbiologist are essential even in endemic areas to correctly diagnose and treat this protean human infection. Existing treatment options, largely based on experience gained > 30 years ago, are adequate but not optimal. In our experience, an initial combination therapy with a three drug-regimen followed by a two-drug regimen for at least six weeks and a combination of two drugs with a minimum of six weeks seems warranted to improve outcome in children and adult patients respectively with laboratory monitoring. A safe and effective vaccine in humans is not yet available. Prevention is dependent upon the control of the disease in animal hosts, effective heat treatment of dairy produce and hygienic precautions to prevent occupational exposure. This review compiles the experiences and diagnostic and treatment paradigms currently employed in fighting this disease.