Evaluation of the high-density agglutination test for Coxiella burnetii antibodies in animals.

The usefulness of the high-density particle agglutination (HDPA) test as a potential tool for the detection of anti-Coxiella burnetii antibodies in animal sera was studied by using 619 cow, 589 dog, and 150 cat serum samples and antisera from rabbits, guinea pigs, and mice. The sensitivity and specificity of the test versus those of the reference microimmunofluorescence test were determined at two different threshold titer values. At the cutoff value of 1:16, the sensitivities of the HDPA test for cow, dog, and cat sera were 94.3, 95, and 91.3%, respectively, and the specificities were 95.5, 95.3, and 91.3%, respectively. At the cutoff value of 1:32, the sensitivities were 86.7, 88.3, and 82.6%, respectively, and the specificities were 99, 99.2, and 98.4%, respectively. For the group of immune laboratory animals all samples from rabbits, guinea pigs, and mice were positive by the HDPA test. The erythrocyte-sensitizing substance from phase II C. burnetii was found to contain protein and carbohydrate, and both fractions are immunoreactive. The study results show that the HDPA test is a useful tool in the epizootiological survey of Coxiella infection in animals.