A Comparison Between Three Serological Tests for Brucella melitensis Infection in Sheep

Authors: Nizar ABUHARFEIL, Mahmoud N. ABO-SHEHADA

Abstract: A comparative study of the Rose Bengal test (RBT), Enzyme-Linked Immunosorbent Assay (ELISA) and complement fixation test (CFT) was performed to analyze sera of two Awassi flocks. Flock A was composed of 215 ewes, naturally infected with brucellosis. None of the animals were vaccinated. Flock B consisted of 336 non-infected non-vaccinated ewes. These served as nega-tive controls. The two flocks were each divided into 4 groups, and samples were collected from one group every 6 months and subjected to bacteriologic and serologic testing. Samples from any aborted ewes were also collected immediately after abortion and 6 weeks later. During the 2 year period of study, 57 ewes spontaneously aborted, out of which Brucella melitensis was isolated from 16 aborted fetuses. Blood from only 2 pregnant ewes were cultured positive to B. melitensis from flock A, and none from flock B. RBT was demonstrated as the most suitable screening method in the field if suspected weak positive (+1) readings are considered negative. ELISA is the most specific and sensitive method since no false negative results were recorded which is in contrast to other methods. One single test is not sufficient to confirm the diagnosis of brucellosis and the combination of two tests should be performed. These are preferably the RBT and ELISA.

Keywords: Sheep, brucellosis, ELISA, RBPT, CFT

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