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Chlamydia Infection (Psittacosis) in Birds – What are the Risks to Bird Owners?

Also known as Chlamydiosis, Chlamydophilosis and Psittacosis, Chlamydia infection presents little danger to most bird owners, but is a real concern for others.  Today we’ll take a look at this much-discussed and often misunderstood condition.

Infection and Immunity

Many parrots, most pigeons and certain other birds (chickens) carry the single-celled bacterium that causes Psittacosis yet remain in good health. 

Known as Chlamydophila psittaci, this micro-organism may not even show up in routine fecal tests, despite being present in the bird.  Chlamydophila psittaci is present in many commercial aviaries…chicks are infected by their parents.  Typically, infected chicks quickly develop an immune response that battles the bacterium, and by age 6 – 12 months are largely immune to the particular strain of C. psittaci to which they were exposed.

How Birds Become Ill

Problems arise when these young birds enter the pet trade – shipment to pet stores, overcrowding, a noisy environment filled with people and similar situations cause the birds a great deal of stress.  This stress weakens the immune system and the bacteria already present in the bird are then able to multiply and cause a serious infection.

Illness can also occur when birds from different breeders are mixed together at pet stores or in one’s home.  The immunity that birds acquire when exposed to low levels of C. psittaci (in the aviary in which they were hatched) is usually effective only against 1 particular strain of the bacteria.  When mixed with birds carrying other strains of C. psittaci, they become ill.

Symptoms/Diagnosis of Chlamydia Infection

Birds rendered ill by exposure to C. psittaci usually develop a respiratory infection.  Their inflamed sinus cavities leak fluids, which eventually ooze out of the nares (nostrils).  These fluids dampen and mat the feathers around the upper bill and cause the bird to sneeze.  In severe cases, the nostrils become blocked, leaving the bird to “pant” with its bill open in an attempt to breathe.  Red, irritated eyes, puffed up feathers and a lethargic demeanor (please see photo of Heron) are also typically seen in birds suffering from respiratory infections.

The liver and other internal organs, air sacs and genitals may also be colonized by bacteria in time.  Birds that recover may suffer reproductive problems if their genitals had been involved in the infection.

Chlamydia infection may be diagnosed by laboratory examination of the stool, fluids leaking from the nares, blood or affected tissues.  Treatment with Doxycycline is often effective.

People at Risk

Heron with ChlamydiosisThe immune systems of most healthy adults prevent C. psittaci from causing any ill effects.

However, immunocompromised people (those with immune systems weakened by HIV or other conditions), the elderly, and infants are at serious risk.  It is strongly suggested that you speak with your personal physician before acquiring a parrot or other bird if you or anyone in your household could be seriously affected by exposure to C. psittaci.  Remember, the bird does not need to be ill in order to infect a person – immune birds, as described above, will appear to be in perfect health.

Further Reading

You can read about other Zoonotic Diseases (those that can be passed from animals to people) on the website of the Arizona Exotic Animal Hospital.


About Frank Indiviglio

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I believe that I was born with an intense interest in animals, as neither I nor any of my family can recall a time when I was not fascinated by creatures large and small. One might imagine this to be an unfortunate set of circumstances for a person born and raised in the Bronx, but, in actuality, quite the opposite was true. Most importantly, my family encouraged both my interest and the extensive menagerie that sprung from it. My mother and grandmother somehow found ways to cope with the skunks, flying squirrels, octopus, caimans and countless other odd creatures that routinely arrived un-announced at our front door. Assisting in hand-feeding hatchling praying mantises and in eradicating hoards of mosquitoes (I once thought I had discovered “fresh-water brine shrimp” and stocked my tanks with thousands of mosquito larvae!) became second nature to them. My mother went on to become a serious naturalist, and has helped thousands learn about wildlife in her 16 years as a volunteer at the Bronx Zoo. My grandfather actively conspired in my zoo-buildings efforts, regularly appearing with chipmunks, boa constrictors, turtles rescued from the Fulton Fish Market and, especially, unusual marine creatures. It was his passion for seahorses that led me to write a book about them years later. Thank you very much, for a complete biography of my experience click here.
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