Abstract

Two hundred selected positive and negative serum samples were collected from dromedary she-camels aged from 1.5-3 years during the period of January 2015 to February 2016 from the market and abattoirs in Halayeb-Shalateen and Abu-Simbel districts and with a history of Brucella melitensis biovar 3 isolation. This was aimed for validation of lateral flow assay (LFA) and in-house indirect enzyme-linked immunosorbent assay (iELISA) to be used in the diagnosis of camel brucellosis. The highest relative sensitivity (98%) was achieved by in-house iELISA coated with lipopolysaccharide antigen and with protein G conjugate -for the first time ever- in the diagnosis of camel brucellosis. LFA offered better performance in terms of relative sensitivity (92%), relative specificity (92.5%) and performance index (184.5). The overall performance of the LFA and in-house iELISA in camels based on both receiver operating characteristic curves (ROCs) and area under ROCs (AUCs) was very good being equal or closer to 0.9. LFA revealed better accuracy than other screening immunoassays tried. The highest positive predictive value was achieved by LFA (0.95), while the corresponding highest negative predictive value (NPV) was attained by in-house iELISA (0.97). All the screening serological tests agreed significantly with LFA and in-house iELISA (LPS). Based on the large association between both LFA, in-house iELISA and the other immunoassays, along with their better diagnostic performance characteristics, authors concluded that both tests were fit for their purpose and valid to be used as rapid screening tests for camel brucellosis as well as useful additions tools to the control and eradication programs in such animal species.

Key words: brucellosis; LFA; iELISA; camel; ROCs; protein G