The purpose of the work. Comparison the diagnostic ability of the ELISA test kits «DIA®-Brucella ab. combi-V» and «ID Screen® Brucellosis Serum Indirect Multi-species» for the detection of antibodies to brucellosis pathogens in various farm animals. Materials and methods. For the analysis there were used 29 positive samples to brucellosis with specific antibodies in different concentrations, 26 of which are serums (22 — from cattle, 2 — from pigs, 1 — from goat, 1 — from camel) and 3 — milk samples from cows. There were used 32 serums (23 — from cattle, 6 — from sheep, 2 — from pigs, 1 — from goat), and 2 milk samples from cows that don’t contain antibodies to brucellosis pathogens for determining the ability of test kits to detect correctly negative samples. There were also used serums from cattle containing antibodies that can lead to false positive results, 1 sample with antibodies to Francisella tularensis, 1 — to Yersinia 03 and 1 — to Yersinia 09. To compare the results in the two test kits, comparative ratios were used that allowed to determine how many times the result obtained in both test kits was higher or less than cut off, that differentiated positive samples from negative. Results of the work. When analyzing 22 cattle serums containing antibodies to B. abortus, the “DIA®-Brucella ab. combi-V” kit determined all samples positive with a results 5.3–10.6 times higher than cut off. The “ID Screen® Brucellosis Serum Indirect Multi-species” test kit identified only 18 positive serums with a maximum value of 1.3 above the cut off. The result of the analysis of 3 samples was doubtful and 1 serum was negative. When analyzing 4 sera from different animals containing antibodies to brucellosis pathogens, the “DIA®-Brucella ab. combi-V” test kit identified all positive samples with the results 8.1–9.4 times higher than cut off. The “ID Screen® Brucellosis Serum Indirect Multi-species” test kit detected specific antibodies in only 3 serums — from pigs and camel. When the goat serum was tested, a doubtful (uncertain) result of the analysis was obtained. When analyzing 3 milk samples from cows containing antibodies to B. abortus in different concentrations there was received a positive result to brucellosis in both test kits. However, ability of the “DIA®-Brucella ab. combi-V” test kit to detect specific antibodies was significantly higher than in comparison test kit. When investigating 32 serums from different animals and 2 milk samples that didn’t contain antibodies to the brucellosis pathogens, a negative result of the analysis was obtained in both test kits. When analyzing cattle serums containing antibodies that can lead to false positive results, both test kits identified 1 sample with antibodies to Francisella tularensis and 1 serum with antibodies to Yersinia 03 with negative result. When analyzing 1 serum with antibodies to Yersinia 09 the result of the analysis was false positive. Conclusions. Studies have shown that the “DIA®-Brucella ab. combi-V” test kit has a high diagnostic capacity. When analyzing 29 blood serums, including samples from different animals, and milk samples from cows containing antibodies to brucellosis pathogens, the test kit identified all samples as positive with results 5.3–10.8 times above the cut off. The “ID Screen® Brucellosis Serum Indirect Multi-species” test kit detected antibodies to brucellosis pathogens only in 24 samples with a maximum value 1.3 times higher than cut off. When investigating 4 serums, 3 samples of which are from cattle and 1 — from goat, the result of the analysis was doubtful (uncertain), 1 cattle serum was identified as negative. The ability of test kits to detect correctly negative samples was comparable. When analyzing 32 serums from different animals and 2 milk samples from cows that do not contain antibodies to brucellosis pathogens, in both test kits, a negative result of the analysis was obtained. For the 3 negative cattle serums, the analysis of which on brucellosis may be incorrect (the presence of antibodies to Yersinia О3, Yersinia О9, Francisella tularensis), in both test kits, for 1 sample with antibodies to Yersinia О9 a false positive result was obtained
How Often Should We Believe Positive Results? Assessing the Credibility of Research Findings in Development Economics
