An evaluation of serological tests in the diagnosis of bovine brucellosis in naturally infected cattle in KwaZulu-Natal province in South Africa.

Songelwayo L Chisi,Gloria Zulu,Prebashni Naidoo,Yoanda Marageni,George W Akol,Henriette Van Heerden

doi:10.4102/jsava.v88i0.1381

Abstract

The diagnostic sensitivity (DSe) of the Rose Bengal test (RBT), the complement fixation test (CFT), the serum agglutination test (SAT), the competitive enzyme-linked immunosorbent assay (cELISA) and the indirect ELISA (iELISA) were determined in naturally infected cattle in KwaZulu-Natal province of South Africa with known infectious status from culture (gold standard). Natural brucellosis infection status of animals was determined by culturing and identification of Brucella abortus biovar 1 from abomasal fluid, milk, hygroma fluid, lymph nodes or uterine discharges samples. The diagnostic specificity (DSp) of the tests mentioned above was determined using samples from known negative herds. There was no statistically significant difference between the tests in their ability to diagnose brucellosis. The RBT and iELISA had the highest DSe of 95.8%, whereas RBT and CFT had the highest DSp of 100%. In South African laboratories, the RBT and CFT serological tests are used, because of the cost efficacy of CFT when compared to the less labour intensive but more expensive iELISA.

Highlights

Brucellosis is a worldwide zoonotic disease of economic and public health importance
The indirect ELISA (iELISA) and Rose Bengal test (RBT) had the highest diagnostic sensitivity (DSe) of 95.8% [95% confidence interval (CI): 85.8% – 99.5%] followed by competitive enzyme-linked immunosorbent assay (cELISA) and complement fixation test (CFT) that had a DSe of 93.9% whilst serum agglutination test (SAT) had a DSe of 92.0 %
Using sera from Brucella-free herds, the CFT and RBT had the highest diagnostic specificity (DSp) of 100.0%, followed by SAT and cELISA with a DSp of 96.8% and 95.0% whilst the iELISA had the lowest DSp of 92.5% (88.3% – 96.2%)

Summary

Introduction

Brucellosis is a worldwide zoonotic disease of economic and public health importance. Bovine brucellosis is a disease of cattle, usually caused by Brucella abortus, less frequently by Brucella melitensis and rarely by Brucella suis (Bishop, Bosman & Herr 1994). In South Africa, 90% of infections in cattle are because of B. abortus bv 1, and 10% are because of B. abortus bv 2 (Bishop et al 1994). The seroprevalence of brucellosis using Rose Bengal test (RBT) and complement fixation test (CFT) in rural cattle in KwaZulu-Natal province is approximately 1.45% according to a survey conducted in rural KwaZulu-Natal communal areas (Hesterberg et al 2008). An earlier seroprevalence survey (November 1981–August 1982) using RBT and CFT in adult female cattle (mostly of commercial animals) at Cato Ridge abattoir in KwaZulu-Natal indicated 1.5% prevalence (Bishop 1984)

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