Zebra Finch Society of Australia

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Chlamydiosis

This is probably the most widespread and common most disease of cage birds including the Zebra Finch. Originally called Psittacosis (Parrot Disease), the name was first changed to Ornithosis (meaning Birds Disease) when it was identified in other species of birds. But today we know that the causative organism is Chlamydia psitaci and therefore the disease is now correctly known as Chlamydiosis (disease cause by Chlamydia).

Confusing? We're only starting. Chlamydia is an intracellular parasite. Over the years the Microbiologists have been debating where to classify it. It is commonly classified as a bacteria, but because of its behaviour and other properties it is often placed by itself. Because it only grows within cells it cannot be grown easily in the lab, like most other species of bacteria. It also finds it easy to hide from antibiotics as well as the birds own immune system by laying dormant within these cells.

Both of these features have traditionally meant that the disease is both hard to detect and hard to treat. Until recently, tests for the disease could only be performed on autopsy specimens. As a result, diagnosis was generally made based upon clinical signs. The ones looked for were green diarrhoea, liver and spleenic damage, respiratory disease and ocular discharge. However, these so called "typical" signs are not reliable as recent advances in testing have shown that the disease is more insidious. The new testing system is called Clearview and was designed for a related disease in humans. It is being used to test droppings from living birds to give a reasonable guide to the birds disease state. The test is available from most Avian Vets in Australia.

The use of this test has brought to light the true nature of the disease, which involves lots of carrier birds, only a few actually sick and are spread through nearly all of our birds. Species of birds previously thought to be rarely affected, in fact are just as prone but without traditional signs. I've diagnosed it in Zebra Finches as well as other finches and canaries. The true nature of Chlamydia in these birds is still been determined, but is primarily stress related, lying dormant in adult birds where it weakens them to other diseases as well as attacking the young birds. Eighty percent of my Clearview tests have been positive. More important has been that these birds respond to the correct treatment for Chlamydia.

The treatment involves using the correct drug for a period of 45 days. Use of any drug should only ever be attempted under the supervision of an avian vet, but this applies even more in this case, as the prolonged nature nature of the treatment and the strict conditions of the antibiotic used cause many problems of their own Side effects of the treatment course, include secondary bacterial infections (particularly resistant strains), fungal and yeast infections, vitamin deficiencies and, indirectly, enterotoxaemia and this doesnt include the organism from the enviroment and to prevent its reintroduction into the flock. Also, some individual birds will refuse to drink to the extent that they will die. I generally warn owners to expect up to ten percent deaths, attributed to the treatment, not the disease. Though this figure is negligable when compared to the long term deaths caused by Chlamydia. Some flocks with this disease rampant were losing upwards of sixty percent of young fledglings, but in most cases it is there and you don't really know it.

Probably the biggest worry with the disease, is that it is a Zoonoses. This means it can cause disease in people, which varies from flu symptoms through to pneumonia. Considering the prevalence of the disease in birds, it is rare in humans, but the risk is strong and should be removed where possible. Also in some states it is a notifiable disease. This means the authorities are told of it's presence in your birds and supervise it's control. If this is not successful, they may force elimination of the birds. It is a disease all bird breeders need to work against and remember, Zebras are not immune.

Terry Martin BVSc.
Taken from "Zebra Finch News" October 1992