Field evaluation of an indirect ELISA for detection of brucellosis in lowland Bolivia.
Bovine brucellosis exists endemically at an estimated prevalence of 10% in the developing dairy industry of Santa Cruz in tropical Bolivia. This paper describes field testing of an FAO/IAEA indirect ELISA for brucellosis, as a possible replacement confirmatory test for the complement fixation test (CFT). The ELISA and CFT were compared on sera from 3 cattle populations: a non-vaccinated negative population, an S19-vaccinated negative population, and a brucellosis-positive population of unknown vaccination status. The CFT and ELISA showed excellent specificities of 100% and 98% respectively against the negative non-vaccinated group. The CFT maintained a specificity of 98% against the S19-vaccinated negative group, but ELISA specificity fell to 83% using a cut-off of 20% of positive control, and 94% using a cut-off of 40% of positive control. Against sera from the positive population, the ELISA gave many more positive reactions than the CFT, probably a combination of both higher sensitivity and lower specificity. It is concluded that as Santa Cruz is entering a phase of brucellosis control rather than eradication, the extra sensitivity of the ELISA is not valuable enough to risk a higher level of false positive reactions, especially as S19 vaccination is being increasingly used.
Kerby
P J
PJ
Laboratorio de Investigación y Diagnóstico Veterinario (LIDIVET), Santa Cruz, Bolivia.
Quiroga
J L
JL
McGrane
J J
JJ
Stagg
D A
DA
D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis* / Q000276:immunology; D001838:Bolivia / Q000453:epidemiology; D002002:Brucella / Q000276:immunology*; D002004:Brucella Vaccine / Q000592:standards / Q000627:therapeutic use; D002007:Brucellosis, Bovine / Q000175:diagnosis* / Q000453:epidemiology* / Q000517:prevention & control; D002417:Cattle; D003168:Complement Fixation Tests / Q000379:methods / Q000592:standards / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000592:standards / Q000662:veterinary*; D005260:Female; D015995:Prevalence; D012680:Sensitivity and Specificity
D000907:Antibodies, Bacterial; D002004:Brucella Vaccine