Enigmatic psittacine chlamydiosis: results of serotesting and isolation attempts, 1978 through 1983, and considerations for the future.

From 1978 through 1983, chlamydiosis was diagnosed by isolation of Chlamydia psittaci from various types of psittacine birds. The organism was isolated from 126 (30.4%) of 414 tissue specimens, with the percentages ranging from 12.5% (budgerigars) to 42.8% (cockatiels), excluding 2 parakeets with 1 isolation (50%). From 1,035 cloacal swab/feces specimens, 51 (4.9%) isolations were made, ranging from 1.4% from African grays (1 of 70) to 27.8% from lovebirds (5 of 18). Positive direct microscopic examination of stained (Gimenez method) tissue impressions correlated with positive isolation at a rate of 79.2% and those found negative by direct examination had a correlation of 87.5%. Direct complement-fixation testing was done on 3,485 sera. Forty-six were unsatisfactory for testing due to their being anticomplementary or reacting with control antigen. The distribution of titers ranged from 2,008 (57.6%) at 8 to 76 (2.2%) at greater than or equal to 256. In serotests and isolation attempts from the same bird, there was 42.8% agreement between titers greater than or equal to 32 and positive isolation. One cockatiel with a complement-fixation titer of 16 yielded a positive isolation, whereas other types of birds with a less than or equal to 16 titer were negative.