Elementary body agglutination for rapidly demonstrating chlamydial agglutinins in avian serum with emphasis on testing cockatiels.

The development and use of a stained chlamydial elementary body agglutination (EBA) antigen for detecting antibody activity in avian sera is described. Examples of serologic results on serum samples from various types of birds indicate the usefulness of EBA, latex agglutination (LA), and direct complement fixation (DCF) in diagnosing avian chlamydiosis. Results of tests on 10 cockatiels examined in clinics indicate that a combination of serology, culture, and/or antigen-detection enzyme-linked immunosorbent assay may be helpful when testing this type of bird. Agreement between EBA, LA, and DCF was 81.8% when testing 407 serum samples from cockatiels of unknown health status. The relationship between positive (> or = 10 titer) antibody activity and known health status of 77 cockatiels revealed that agreement between the two criteria was only 59.7%. Of 13 Chlamydia-inoculated cockatiels, seven birds seroconverted from negative to positive by EBA; five seroconverted by DCF. Only the five birds that seroconverted by both EBA and DCF were culture-positive for chlamydiae. None of 15 sham-inoculated control cockatiels developed detectable antibody activity, and none of 10 cultured were positive. In tests with column-separated IgM and IgG, EBA detected only IgM activity, LA detected IgM and IgG activity, and DCF detected only IgG activity.