Breaking the Diagnostic Enigma: Brucella Infection in the Spectrum of Pyrexia of Unknown Origin at a Tertiary Care Hospital in North India

Background: Brucellosis is a neglected zoonotic infection that poses significant public health concerns. It is endemic in various regions of Asia, notably in India. It contributes to pyrexia of unknown origin and has the potential to cause life-threatening multisystem disease. Objectives: The focus of this work was to diagnose brucellosis by IgM/IgG ELISA. Methods: A total of 94 serum samples were collected and processed for screening of brucella by Enzyme-Linked Immunosorbent Assay. Results: Human brucellosis was prevalent in a study of 94 individuals with suspected Pyrexia of Unknown Origin (PUO), with diverse infectious causes identified. The diagnostic success rate was 61.7%, and Brucella-positive cases (mean age 34.08±15.14) were more common in males (69.2%) and rural individuals (61.5%), particularly farmers/unskilled laborers and housewives. The Orthopedics/Rheumatology ward exhibited a higher prevalence (53.8%), with clinical manifestations including pyrexia, arthralgia, anemia, backache, splenomegaly, hepatomegaly, and thrombocytopenia/thrombocytosis. PCR analysis identified one B. abortus case (1.1%), and serological/molecular analyses revealed distinct patterns, including solely IgG positive (3.2%), solely IgM positive (9.6%), and positivity for both IgM and PCR (1.1%). Conclusion: The potential for unusual clinical presentation and the low titers of serologic reactivity remind us that brucellosis remains a diagnostic challenge that requires clinical suspicion and thorough evaluation.