title: Diagnostic performance of serological tests for swine brucellosis in the presence of false positive serological reactions.
abstract: Swine brucellosis caused by Brucella suis biovar 2 is an emerging disease in Europe. Currently used diagnostic tests for swine brucellosis detect antibodies to the O-polysaccharide (O-PS) of Brucella smooth lipopolysaccharide (S-LPS) but their specificity is compromised by false-positive serological reactions (FPSRs) when bacteria carrying cross-reacting O-PS infect pigs. FPSRs occur throughout Europe, and the only tool available for a specific B. suis diagnosis is the intradermal test with Brucella protein extracts free of O-PS or S-LPS. Using sera of 162 sows naturally infected by B. suis biovar 2, 406 brucellosis-free sows, and 218 pigs of brucellosis-free farms affected by FPSR, we assessed the diagnostic performance of an indirect ELISA with rough LPS (thus devoid of O-PS) and of gel immunodiffusion, counterimmunoelectrophoresis, latex agglutination and indirect ELISA with O-PS free proteins in comparison with several S-LPS tests (Rose Bengal, complement fixation, gel immunodiffusion and indirect ELISA). When adjusted to 100% specificity, the sensitivity of the rough LPS ELISA was very low (30%), and adoption of other cut-offs resulted in poor specificity/sensitivity ratios. Although their specificity was 100%, the sensitivity of protein tests (ELISA, latex agglutination, counterimmunoelectrophoresis, and gel immunodiffusion) was only moderate (45, 58, 61 and 63%, respectively). Among S-LPS tests, gel immunodiffusion was the only test showing acceptable sensitivity/specificity (68 and 100%, respectively). Despite these shortcomings, and when the purpose is to screen out FPSR at herd level, gel immunodiffusion tests may offer a technically simple and practical alternative to intradermal testing.
authors: Unidad de Sanidad Animal, Centro de Investigación Tecnología Agroalimentaria (CITA) del Gobierno de Aragón, Av. Montañana, 930, 50059 Zaragoza, Spain.
authors: L
authors: L
authors: Dieste-Pérez
authors: Unidad de Sanidad Animal, Centro de Investigación Tecnología Agroalimentaria (CITA) del Gobierno de Aragón, Av. Montañana, 930, 50059 Zaragoza, Spain.
authors: J M
authors: JM
authors: Blasco
authors: Unidad de Sanidad Animal, Centro de Investigación Tecnología Agroalimentaria (CITA) del Gobierno de Aragón, Av. Montañana, 930, 50059 Zaragoza, Spain.
authors: M J
authors: MJ
authors: de Miguel
authors: Instituto de Salud Tropical y Dpto. de Microbiología y Parasitología, Universidad de Navarra, 31008 Pamplona, Spain.
authors: I
authors: I
authors: Moriyón
authors: Unidad de Sanidad Animal, Centro de Investigación Tecnología Agroalimentaria (CITA) del Gobierno de Aragón, Av. Montañana, 930, 50059 Zaragoza, Spain. Electronic address: pmmunnoz@cita-aragon.es.
authors: P M
authors: PM
authors: Muñoz
mesh_terms: D000818:Animals; D041021:Brucella suis / Q000302:isolation & purification*; D002006:Brucellosis / Q000175:diagnosis / Q000662:veterinary*; D003168:Complement Fixation Tests; D003378:Counterimmunoelectrophoresis; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D005060:Europe; D005189:False Positive Reactions; D005779:Immunodiffusion; D007428:Intradermal Tests; D007841:Latex Fixation Tests; D012395:Rose Bengal; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000592:standards*; D013552:Swine; D013553:Swine Diseases / Q000175:diagnosis*
chemical_list: D012395:Rose Bengal
keywords: Brucella suis; Cytosolic proteins; FPSR; Porcine brucellosis; Serological tests