Psittacosis in birds is caused by infection with the bacterium Chlamydia psittaci. This organism is carried and shed by many bird species, especially parrots, parakeets, cockatiels, and other psittacines. Birds become infected by inhaling or ingesting the bacteria from contaminated droppings, respiratory secretions, feather dust, or shared food and water. It can also pass from a mother bird to her chicks in the nest. Because the bacteria can survive in dried droppings and cage dust, a bird does not need direct contact with a sick bird to become infected.

Psittacosis is also known as parrot fever or ornithosis. It is a zoonotic disease, meaning it can spread from birds to people, so recognising the causes and early signs matters for both your bird and your household. The MSD Veterinary Manual notes that infection is most often introduced into a home or aviary by a new bird that appears healthy but is shedding the bacteria intermittently.

What causes psittacosis in birds?

The direct cause is the bacterium Chlamydia psittaci. This is an obligate intracellular bacterium, meaning it must live inside host cells to multiply. It has two main forms: an infectious form that survives in the environment and a reproductive form that grows inside the bird's cells. This dual lifecycle helps explain why the infection can persist in a bird for a long time, sometimes without obvious signs, and why it can flare up during stress.

Infection begins when a bird takes in the bacteria through the eyes, nostrils, or mouth. From there, the organism spreads to the respiratory tract, air sacs, liver, spleen, and sometimes the digestive tract. The severity of illness depends on the bird's species, age, immune status, and the amount of bacteria it encountered. Young birds, newly imported birds, and birds living in crowded or poorly ventilated conditions tend to develop more serious disease.

How psittacosis spreads between birds

Transmission happens in several well-recognised ways:

• Inhalation of contaminated dust: Dried droppings and feather dust can carry the bacteria. When a bird flaps its wings or when a cage is cleaned, these particles become airborne and can be inhaled.
• Ingestion: Birds that eat or drink from bowls contaminated with droppings or respiratory secretions can pick up the bacteria.
• Direct contact: Beak-to-beak contact, mutual feeding, and close proximity in crowded cages increase the risk.
• Vertical transmission: An infected mother bird can pass the bacteria to her chicks in the nest or through the egg.
• Carrier birds: Birds that have recovered from infection can still shed the bacteria intermittently, especially during stress such as transport, diet changes, or breeding.

Because carriers can look completely normal, introducing a new bird without a veterinary check and a period of separation is one of the most common ways psittacosis enters a home flock. The Association of Avian Veterinarians recommends testing and quarantine for new birds, but the details of any testing or quarantine plan should come from your own veterinarian.

Risk factors that make psittacosis more likely

Not every bird exposed to Chlamydia psittaci becomes seriously ill. Several factors influence whether infection takes hold and how severe it becomes:

Understanding these factors helps you reduce exposure, but it does not replace veterinary diagnosis. Only a veterinarian can confirm psittacosis through specific tests.

Signs of psittacosis in birds

Signs can range from mild to severe and may come on suddenly or gradually. Common signs include:

• Lethargy and fluffed feathers
• Reduced appetite and weight loss
• Difficulty breathing, tail bobbing, or open-mouth breathing
• Nasal or eye discharge
• Greenish or yellowish droppings
• Swollen eyelids or conjunctivitis
• In some cases, neurological signs such as tremors or imbalance

These signs overlap with many other avian illnesses, including other bacterial and viral infections. A veterinarian will consider the bird's history, clinical signs, and specific laboratory tests before making a diagnosis. The MSD Veterinary Manual notes that psittacosis should be suspected in any bird with respiratory or digestive signs that do not respond to general supportive care.

How veterinarians diagnose psittacosis

Diagnosis is not based on signs alone. Veterinarians use a combination of tests, which may include:

• PCR testing on swabs from the choana, conjunctiva, or cloaca
• Blood tests to detect antibodies
• Imaging such as radiographs to assess air sacs and internal organs
• Complete blood count and biochemistry to evaluate overall health

Because shedding can be intermittent, a single negative test does not always rule out infection. Your veterinarian may recommend repeat testing or additional diagnostics. They will also consider whether other birds or people in the household could be at risk.

Treatment categories for psittacosis

Treatment of psittacosis in birds is prescription-only and must be directed by a veterinarian. The most commonly used class of antibiotics for this infection is tetracyclines, particularly doxycycline. Other antibiotic classes may be considered based on the bird's condition and your vet's assessment.

When a veterinarian prescribes an antibiotic, they will choose the specific product and form based on the bird's species, size, and clinical state. In the WePetVerse range, products such as Doxy 20% B and Doxy 20% Pwd B 100g are doxycycline-based options intended for avian respiratory support under veterinary guidance. Combination products like Dox-T Pwd B 100g pair doxycycline with tylosin, another antibiotic, for situations where a vet determines broader coverage is needed. B-Pen AB B is a penicillin-based powder that may be used for certain bacterial infections in birds, but it is not the primary choice for psittacosis.

Never start, stop, or combine any antibiotic without veterinary direction. The choice of drug, the decision to use a single agent or a combination, and the duration of therapy are medical decisions that depend on diagnosis, response, and follow-up testing. Your veterinarian will also advise on supportive care such as fluids, nutrition, and housing adjustments. For a full list of avian antibiotic options, see the Bird Antibiotics collection.

Preventing psittacosis in your home flock

Because the bacteria spread through droppings, dust, and close contact, prevention focuses on hygiene and biosecurity:

• Quarantine new birds away from existing birds for a period your veterinarian recommends, and have them examined before introduction.
• Clean cages, food bowls, and water containers regularly. Dampen surfaces before cleaning to reduce dust.
• Ensure good ventilation without creating drafts.
• Avoid overcrowding and minimise stress from transport or sudden changes.
• Wash your hands after handling birds or cleaning cages, especially if you have a weakened immune system.
• Watch for signs of illness in any bird and isolate it promptly if you notice something wrong.

These measures reduce the chance of introduction and spread, but they cannot eliminate risk entirely. Regular veterinary check-ups help catch problems early.

When to call your vet

Contact an avian veterinarian promptly if you notice any of these red-flag signs:

• Laboured breathing, tail bobbing, or open-mouth breathing
• Persistent lethargy or fluffed feathers
• Not eating or drinking for more than a few hours
• Abnormal droppings that are watery, discoloured, or bloody
• Eye or nasal discharge
• Weight loss or a noticeable drop in activity
• Any sudden change in behaviour or posture

Psittacosis can worsen quickly, and early veterinary care gives your bird the best chance of recovery. If anyone in your household develops flu-like symptoms after contact with a sick bird, they should seek medical advice and mention the bird's illness.

Frequently asked questions

Can psittacosis spread to humans?

Yes, psittacosis is a zoonotic disease, meaning it can spread from birds to people. Humans typically become infected by inhaling contaminated dust from droppings or respiratory secretions. Symptoms in people resemble flu and can include fever, cough, and headache. If you or a family member develop these signs after contact with a sick bird, seek medical advice and mention the bird's illness.

How long does psittacosis live in the environment?

The bacteria can survive in dried droppings and cage dust for weeks under favourable conditions. This is why cleaning with dust control and good ventilation matters. However, the exact survival time depends on temperature, humidity, and organic material. Routine disinfection and damp cleaning reduce environmental contamination, but always follow your veterinarian's advice for your specific situation.

Are some bird species more prone to psittacosis?

Yes, psittacine birds such as parrots, cockatiels, parakeets, and macaws are especially susceptible. Doves, pigeons, and some poultry can also carry the bacteria. Within a species, young, stressed, or immune-compromised birds are more likely to develop severe illness. Your veterinarian can advise on risks specific to your bird.

Can a bird be a carrier without showing signs?

Yes, birds can be carriers and shed the bacteria intermittently without obvious signs, especially during stress. This is one reason why quarantine and testing new birds is important. A carrier can infect other birds in the home. Only a veterinarian can determine if a bird is a carrier through appropriate testing.

What should I do if I suspect my bird has psittacosis?

Isolate your bird from other birds and contact an avian veterinarian immediately. Do not start any medication on your own, as antibiotics must be prescribed and monitored by a vet. Provide supportive care such as warmth and easy access to food and water, and follow your vet's instructions. Also inform anyone who has had close contact with the bird.

Is there a vaccine for psittacosis in birds?

No, there is no widely available vaccine for psittacosis in birds. Prevention relies on biosecurity, hygiene, quarantine of new birds, and regular veterinary care. If your bird is diagnosed with psittacosis, your veterinarian will guide treatment and follow-up testing to confirm recovery.

Products mentioned in this guide

• Doxy 20% B — from $49.95 (Antibiotic)
• B-Pen AB B — from $69.95 (Antibiotic)
• Dox-T Pwd B 100g — from $69.99 (Antibiotic)
• Doxy 20% Pwd B 100g — from $59.99 (Antibiotic)

Browse all Bird Antibiotics →

Sources and further reading

General veterinary background for this article:

• MSD Veterinary Manual
• Merck Veterinary Manual
• American Veterinary Medical Association
• FDA Center for Veterinary Medicine
• World Organisation for Animal Health
• Association of Avian Veterinarians

A note on veterinary advice

This article is general educational information about animal health products and is not veterinary advice. It does not contain dosing instructions. Always consult a licensed veterinarian before starting, stopping, or changing any medication or supplement for your animal. Medications for animals should never be used by humans.