Diagnosis of Chronic Brucellosis with Interferon-Gamma Quantification

Abstract

Background: Brucellosis can vary in severity and duration, requiring multiple tests for diagnosis. Its prevalence in Iraq complicates the interpretation of test results. Objective: This study aimed to develop a diagnostic tool leveraging variations in γ interferon to aid the immune system in recognizing illness. Methods: A comparative study was conducted at Anbar Teaching Hospital from October 2022 to September 2023. 86 blood samples were collected from the outpatient infectious clinic, comprising 43 confirmed Rose Bengal-positive and 43 negative cases. Various diagnostic methods were employed, including specific IgM and IgG antibodies, culture, polymerase chain reaction (PCR), and gamma interferon targeting the brucella antigen. Results: Patients with positive results exhibited symptoms validated by PCR. The gamma interferon assay demonstrated 79.2% sensitivity and 100% specificity. PCR showed 89.3% sensitivity and 100% specificity, while brucella-specific IgG had 21.4% sensitivity and 100% specificity. Other laboratory studies, including Brucella-specific IgM, showed 100% sensitivity and specificity, with positive Brucella culture observed in only one case. Conclusion: Chronic brucellosis's sustained high levels of gamma interferon may offer better follow-up for patients with lingering symptoms than Brucella-specific IgG, especially after acute cases with low-grade fever.