Psittacosis is a zoonotic disease, which means that it can be transmitted from birds to people. It is caused by the bacterium Chlamydophila psittaci. It is best known for affecting parrots and parrot-like birds but can affect other avian species as well as being passed to mammals and humans. It can be shed in body secretions – for example, faecal, nasal and ocular fluids. 

Chlamydophila organisms survive in the environment for several weeks and may be distributed by dust. The infection is mainly airborne; with the pathogen first reproducing in the respiratory tract.

Once psittacosis (known as chlamydophilosis / ornithosis in humans) is passed to humans it cannot usually be passed from human to human, nor human back to birds. It is a chronic disease posing a particular risk to children, the elderly and immunosuppressed individuals.

Clinical signs

• In humans the common signs are headaches, neck pain and fever progressing to respiratory infections. It can also cause fatal heart disease.
• Signs you may see in your bird include swollen eyelids, nasal discharge, sneezing, depression, ruffled feathers, weight loss, inappetence, bright green diarrhoea, feather colouration changes, occasionally nervous signs, or even sudden death.

Diagnosis

• Psittacosis can be a difficult disease to definitively diagnose, but may be suspected on a blood test or x-rays. The best way to identify the Chlamydophila organism is by testing a faecal sample collected over a 3 day period, but even this may not pick up all cases as the organism is only shed intermittently.

Treatment

• Treatment of birds generally involves an antibiotic course for 6 weeks and follow-up tests. Even a bird that tests “free” of chlamydophila after treatment cannot be considered clear of infection as a negative test can only indicate there is no organisms shed at the point of testing. Once the infection is over many birds are susceptible to re-infection or re activation of the organism. Therefore due to these issues and the human health risk, euthanasia may be considered in some situations.