Birds do not have to show symptoms of disease in order to transmit clamydia. There are no specific signs that are characteristic of psittacosis. Of course, these signs may be related to disease other than psittacosis. Many birds carry the chlamydidal organism but do not show any signs of disease under stable conditions. These birds may become sick after some stressful occurrence, or breeding birds may pass the organism on to their offspring, which may die in the nest or at weaning.
Young birds are more susceptible to a severe debilitating infection than are adult birds.
Positive diagnosis of chlamydiosis in the live bird is sometimes very difficult, depending on the species, length of time since exposure, and general condition of the bird. Because it is far easier to diagnose a bacterial problem, the chlamydiosis may be missed. Some chlamydiosis screening tests are available through out laboratory services, and new tests are being developed that will help your veterinarian diagnose psittacosis in his clinic. There is no single diagnostic test in the live bird that can absolutely show the presence of chlamydia in all cases. Your avian veterinarian may be able to make a presumptive diagnosis of psittacosis based on history, clinical signs, X-rays, blood work or other diagnostic methods.