Avian Chlamydiosis

Several diagnostic methods based on culture technique, test for antibody/antigen, and more recently PCR, similar to those described above, are available for identifying AC in birds. A confirmed case of AC is defined on the basis of at least one of the following laboratory results: a) isolation of C. psittaci from a clinical specimen, b) identification of chlamydial antigen by immunofluorescence (fluorescent antibody [FA]) of the bird’s tissues, c) a greater than fourfold change in serologic titer in two specimens from the bird obtained at least 2 weeks apart and assayed simultaneously at the same laboratory, or d) identification of C. psittaci within macrophages in smears stained with Gimenez or Macchiavellos stain or sections of the bird’s tissues. A probable case of AC is defined as compatible illness and at least one of the following laboratory results: a) a single high serologic titer in one or more specimens obtained after the onset of signs or b) the presence of C. psittaci antigen (identified by ELISA, PCR, or FA) in feces, a cloacal swab, or respiratory or ocular exudates. A positive serologic test result is evidence that the bird was infected by C. psittaci at some point, but it might not indicate that the bird has an active infection. False-negative results can occur for birds that have acute infection when they are sampled before seroconversion. Treatment with an antimicrobial agent can diminish the antibody response. A single testing method might not be adequate because of the diversity of reactions with immunoglobulins from the various avian species. Therefore, use of a combination of antibody- and antigen-detection methods is recommended, particularly when only one bird is tested. When specimens are obtained from a single bird, serologic testing is most useful when a) signs of disease and the history of the flock or aviary are considered and b) serologic results are compared with the white blood cell counts and liver-enzyme activities. A greater than fourfold increase in titer of paired samples or a combination of a titer and antigen identification is needed to confirm a diagnosis of AC.

• Protect persons at risk. Inform all persons in contact with infected birds about the nature of the disease. Instruct them to wear protective clothing, gloves, a disposable surgical cap, and a respirator with an N95 rating or a higher-efficiency respirator when cleaning cages or handling infected birds. Surgical masks might not be effective in preventing transmission of C. psittaci. When necropsies are performed on potentially infected birds, wet the carcass with detergent and water to prevent aerosolization of infectious particles and work under a biological safety cabinet (or equivalent).

• Maintain accurate records of all bird-related transactions to aid in identifying sources of infected birds and potentially exposed persons. Records should include the date of purchase, species of birds purchased, source of birds, and any identified illnesses or deaths among birds. In addition, the seller should record the name, address, and telephone number of the customer and the band numbers if applicable.
• Avoid purchasing or selling birds that have signs of AC. Signs include ocular or nasal discharge, diarrhea, or low body weight.
• Isolate newly acquired birds. Isolate the birds – including those that have been to shows, exhibitions, fairs, and other events – for 30-45 days, and test or prophylactically treat them before adding them to a group.
• Test birds before they are to be boarded or sold on consignment. House them in a room separate from other birds.
• Practice preventive husbandry. Position cages to prevent the transfer of fecal matter, feathers, food, and other materials from one cage to another. Do not stack cages, and be sure to use solid-sided cages or barriers if cages are adjoining. The bottom of the cage should be made of a wire mesh. Litter that will not produce dust (e.g., newspapers) should be placed underneath the mesh. Clean all cages, food bowls, and water bowls daily. Soiled bowls should be emptied, cleaned with soap and water, rinsed, placed in a disinfectant solution, and rinsed again before reuse. Between occupancies by different birds, cages should be thoroughly scrubbed with soap and water, disinfected, and rinsed in clean, running water. Exhaust ventilation should be sufficient to prevent accumulation of aerosols.
• Prevent the spread of infection. Isolate birds requiring treatment. Rooms and cages where infected birds were housed should be cleaned immediately and disinfected thoroughly. When the cage is being cleaned, transfer the bird to a clean cage. Thoroughly scrub the soiled cage with a detergent to remove all fecal debris, rinse the cage, disinfect it (allowing at least 5 min. of contact with the disinfectant), and rerinse the cage to remove the disinfectant. Discard all items that cannot be adequately disinfected (e.g., wooden perches, ropes, nest material, and litter). Minimize the circulation of feathers and dust by wet-mopping the floor frequently with disinfectants and preventing air currents and drafts within the area. Reduce contamination from dust by spraying the floor with a disinfectant or water before sweeping it. Do not use a vacuum cleaner, as it can aerosolize infectious particles. Frequently remove waste material from the cage (after moistening the material), and burn or double-bag the waste for disposal. Care for healthy birds before handling isolated or sick birds.
• Use disinfection measures. C. psittaci is susceptible to most disinfectants and detergents as well as heat; however, it is resistant to acid and alkali. A 1:1,000 dilution of quaternary ammonium compounds (e.g., RoccalŽ or ZephiranŽ) is effective, as is 70% isopropyl alcohol, 1% LysolŽ, 1:100 dilution of household bleach (i.e., 2.5 tablespoons per gallon), or chlorophenols. Many disinfectants are respiratory irritants and should be used in a well-ventilated area. Avoid mixing disinfectants with any other product.