Application of serum based PCR and Fluorescence Polarization Assay for diagnosis of brucellosis among people occupationally at risk to disease

Abstract

Brucellosis is an important and overlooked zoonotic disease especially in developing countries having great potential to badly affect the people occupationally exposed to disease. In humans, the disease is usually marked with undulant fever, headache, fatigues, back pain, general malaise and arthritis. There have been a number of published studies available focusing on the serological surveillance in Pakistan but very little has been done using serum as clinical specimen for Polymerase Chain Reaction (PCR) and advanced serological techniques like Fluorescence Polarization Assay (FPA). In this study we have used serum as clinical sample for molecular and serological diagnosis of brucellosis in occupationally exposed human population to address the limitations associated with safe handling of field samples and current diagnostic procedures. Sera from 110 volunteers were collected and analyzed by employing serology (Rose Bengal Test, competitive ELISA, FPA) and serum PCR assay. Seropositivity was observed in 4.5% (5/110), 9% (10/110) and 31% (34/110) of samples with RBT, cELISA and FPA, respectively. The PCR assay could detect about 38% (42/110) samples (p < 0.05). Serum PCR and FPA were able to detect more positive cases in each category of human population sampled. We found serum could be used as more dependable and safer clinical specimen for both serological and molecular investigations. Together with serum PCR, this study strongly recommends the introduction of FPA into routine clinical diagnosis for brucellosis. Our findings described here will help to understand and let decision makers to adopt and implement better choices for future brucellosis control measures.