Rapid enzyme-linked immunosorbent assay for the diagnosis of human brucellosis in surveillance and clinical settings in Egypt Moustafa A. Fadeel, PhD, Momtaz O. Wasfy, PhD, Guillermo Pimentel, PhD, John D. Klena, PhD, Francis J. Mahoney, MD, Rana A. Hajjeh, MD. B rucellosis is a serious disease endemic to the Middle East, Central and South America, and other parts of the developing world. It is acquired through ingestion of contaminated raw or unpasteurized milk or milk products and through contact with infected animals (example, cattle, goats). 1,2 A laboratory-based sentinel surveillance conducted in Egypt from 1999 to 2003 identiied typhoid fever and brucellosis as the From the United States Naval Medical Research Unit #3 (Fadeel, Wasfy, Pimentel, Klena), World Health Organization (Mahoney), Regional Ofice for the Eastern Mediterranean, Cairo, Egypt and the Center for Disease Control and Prevention (Hajjeh), Atlanta, GA, United States of America. Received 14th December 2005. Accepted for publication in inal form 9th April 2006. Address correspondence and reprint request to: Dr. Moustafa A. Fadeel, United States Naval Medical Research Unit-3, PSC 452, Box 5000 (Attn: Code 304A), FPO AE 09835-0007, United States of America. Tel. +2 (02) 3480360. Fax. +2 (02) 3427121. E-mail. fadeelm@namru3.med.navy.mil 975 most common causes of acute febrile illness (AFI). 3 A separate population-based surveillance conducted in Fayoum, Egypt, during 2003 revealed that 47% of brucellosis patients were clinically misdiagnosed as having typhoid fever. 1,3 Clinically, brucellosis presents as an AFI with few speciic signs and can be misdiagnosed or confused with other febrile diseases such as typhoid Objectives: To optimize and standardize an enzyme- linked immunosorbent assay (ELISA) for rapid diagnosis of human brucellosis in clinical cases identiied during a surveillance study for acute febrile illness (AFI). Methods: Serum samples from patients presenting with AFI at 13 fever hospitals across Egypt between 1999 and 2003 were kept frozen at NAMRU-3 and used in this study. The assay was evaluated in 5 subject groups: brucellosis cases conirmed by blood culture (group I, n=202) 87% positive by standard tube agglutination test (TA), brucellosis cases exclusively conirmed by TA (group II, n=218), blood cultures from AFI cases positive for bacterial species other than Brucella (group III, n=103), AFI cases with unexplained etiologies (group IV, n=654), and healthy volunteers (group V, n=50). All members of groups III-V were negative for brucellosis by TA. Results: Sensitivity and speciicity of ELISA for total ABSTRACT speciic antibodies were ≥96% versus 87% for TA as compared to microbial culture, the current gold standard method for Brucella identiication. Assessment of Brucella antibody classes by ELISA in random subsets of the 5 groups showed signiicantly high (p>0.001) levels of anti Brucella IgG (≥81%) and IgM (≥90%) in groups I and II only. Conclusions: The obtained sensitivity and speciicity results indicate that our ELISA is more suitable for AFI surveillance and clinical settings than blood culture and TA. The developed assay is also cost-effective, easier to use, faster, and the coated plates can be stocked for at least 8 months, providing a potential for ield use and automation. Saudi Med J 2006; Vol. 27 (7): 975-981 05Rapid20051460_(1).indd 975 2/7/06 1:03:11 pm