Chlamydophilosis

Chlamydophilosis Testing

Introduction

Chlamydophilosis has been one of the major diagnostic problems in avian practice since it was first described in the late 1800’s. In the past twenty years, numerous attempts have been made at developing a sensitive and specific test for the diagnosis of this avian disease. Immunological assays formed the base for the first assays available: latex agglutination, complement fixation, BELISA, and antigen ELISA as well as the Avian and Wildlife Laboratory’s IFA. Recently, DNA probe technology has also been applied to this diagnostic problem.

General Information on the Avian and Wildlife Laboratory IFA Test

This test uses a methodology similar to that used in traditional test assays for distemper, parvovirus, and FIP. The test sample is incubated with a Chlamydia infected cell substrate which is subsequently washed before the application of a FITC conjugated antibody which has reactivity with psittacine immunoglobulins. After a second incubation and wash, the sample reactivity with the substrate is evaluated with the use of a fluorescent microscope. Samples are judged for specific Chlamydial staining. Results are reported as titers.

Positive confirmed results have been found on all common psittacine species including cockatiels, budgies, and lovebirds. In addition, this test has been used successfully with samples including from the following species: pigeon, duck, goose, eagle, ostrich, emu, hawk, cat, and dolphin (the latter two with procedural changes).

On a daily basis, this laboratory reports 8-9% positive samples on routine submissions.

What does a positive mean?

Positive serologies are present in the following types of cases: acute infection, chronic infection, and past infection/exposure. As this test detects a long lived IgG-type antibody, successful treatment does not always result in a quick return to seronegative status. Some birds, in the absence of chronic infection, have remained positive on the IFA test for up to a year after treatment.
Because of this reactivity, the IFA test is excellent at detecting chronically infected birds and thus is recommended by our laboratory for a test choice in clinically normal new bird/well bird screens. Likewise, the weakness of the test is detection of acutely infected birds. IgG-like titers often do not develop until 10-14 days after infection. Thus, acutely presenting birds in this early window of time may not be positive on our test.

How does the elementary body agglutination test help?

The elementary body agglutination test or EBA provides another method to detect seroconversion. As agglutination tests are naturally sensitive to IgM antibodies, this test has been described as being more sensitive to early stages of infection. In textbook antibody responses, IgM antibody is first produced by day 5 to 7 and IgG antibodies are not detected until 10-14 days after exposure. Notably, IgG antibodies can also result in agglutination and so this test can also serve to confirm IFA serology positive results albeit with possible less sensitivity than the IFA serology test. The EBA is offered by the UGA IDL and is run at a screening titer initially. For an extra fee, a quantitative titer can be completed.

Other Tests to Assist in Diagnosis

The Avian and Wildlife Laboratory also offers the serology test in conjunction with plasma protein electrophoresis (EPH). The latter test affords the chance to look at the circulating plasma proteins in your patients (see other flyer for more information). In classic acute chlamydophilosis cases the following protein changes are usually observed: decreased albumin, moderate increase in beta globulins, and moderate to marked increases in gamma globulins. This particular pattern is rarely observed with other diseases. Thus, the combination of serology and EPH can minimize your diagnostic possibilities.

Chronic infection remains a problem to diagnose. EPH often will show mild to moderate increases in beta globulins in these seropositive cases. However, accessory testing of liver enzymes, bile acids, and general hematology assays will assist in diagnosis.

Chlamydophilosis DNA probe applications are also offered by the Avian and Wildlife Laboratory and are sent to the University of Georgia. This is a high sensitivity technique that is excellent for the diagnosis of acute infection.

Sample collection and preparation

  • Chlamydophila Serology by IFA – prefer 0.1ml plasma separated from a green top tube to a small microfuge transport tube. Refrigeration acceptable for 5 days before testing. If longer delay, freeze separated plasma. Ship with or without a cold pak as long as shipment is overnight. Mild hemolysis and lipemia are acceptable.
  • Chlamydophila Serology by EBA – prefer 0.1ml serum separated from a red top tube to a small microfuge transport tube. Hemolysis and lipemia are not acceptable.
  • Chlamydophila DNA testing. This test is performed by the University of Georgia. Samples are sent to them on a weekly basis. Preferred samples are heparinized whole blood (0.1ml in green top tube, unspun) and/or fecal-cloacal swab. Do not use gel transport culturettes. Prefer Modified Stuart’s medium in glass ampule. Refrigerate until transport. Cold pak optional.