Protean clinical manifestations and diagnostic challenges of human brucellosis in adults: 16 years' experience in an endemic area.

A prospective study was carried out to elucidate the clinical, epidemiological and laboratory features of human brucellosis. A total of 26 948 blood samples (from adults aged 15 years and above) were screened for serological evidence of brucellosis over a period of 16 years. The slide agglutination/Rose Bengal plate agglutination test gave positive results in 517 patients, of which 509 had detectable titres by the standard tube agglutination test (SAT). The diagnosis of brucellosis was documented in 495 (1.8 %) patients based on diagnostic titres (> or = 1 : 160, 490 cases) and rising titres from insignificant titres (four cases) by serology and for one case by blood-culture isolation alone. Blood cultures were carried out in 345 cases, of which 191 cases (55.3 %) yielded Brucella melitensis. In 77/79 cases undertaken for follow up, there was a steady fall in 2-mercaptoethanol (2ME) agglutination titres along with clinical improvement (P < 0.01). SAT titres remained detectable in most cases for a longer period in spite of an effective antimicrobial therapy and clinical recovery. A substantial number of patients (84.2 %) presented with fever, this being the only complaint in 51.1 % of the cases. Complications were present in 8.8 % of the patients (arthritis excluded): this included the unusual complications of hydrocele (two cases), Stevens-Johnson syndrome (one case) and urinary tract infection (one case). Brucella agglutinins were demonstrated in synovial, testicular, hydrocele and cerebrospinal fluids. There was no clinical suspicion of brucellosis in 439 cases (88.7 %) and the diagnosis was made only by routine serology. A two-drug regimen for 42-84 days with a follow-up 2ME test resulted in lower levels of relapse. These results suggest that, in endemic areas of the world, it should be mandatory to screen routinely for brucellosis due to protean clinical manifestations.