What Is Psittacosis?

Medically Reviewed by Sabrina Felson, MD on March 21, 2023
4 min read

Psittacosis is a zoonosis — an infection transmitted from vertebrate animals to humans. Psittacosis is a disease of birds. You get psittacosis from close contact with infected birds, most often pet parrots. You're also at risk if your work brings you in contact with animals. The disease can be severe and need hospitalization.

Psittacosis is also known as ornithosis. It is a disease of birds caused by bacteria named Chlamydia psittaci. It is most common in parrots, parakeets, cockatiels, and budgerigars. Pigeons, doves, and poultry like turkeys and ducks also get this infection. Chickens rarely have this infection.

Transmission between humans is rare. Children are not often infected. Your bird may not appear sick when it transmits the disease.

Many infected birds have no symptoms and appear well. Some birds with Chlamydia psittaci infection (avian chlamydiosis) may have a poor appetite, inflamed eyes, diarrhea, and breathing difficulty.

Infection with the bacteria Chlamydia psittaci causes psittacosis in humans. Infected birds pass the bacteria into their feces. You can get the disease by breathing in airborne particles which carry the bacteria released from an infected bird's dried feces, feathers, or respiratory secretions. Handling the bird's plumage can also infect you. 

Caged birds generate infectious particles when they spread their wings. Cage cleaning also puts you at risk of infection. You can get psittacosis with brief contact such as visiting bird parks. Bird bites and beak-to-mouth contact also transfers this infection. 

Chlamydia psittaci are unusual bacteria — they grow inside host cells. That makes them difficult to diagnose by the usual laboratory culture methods. Treatment of such infections needs medicines (antibiotics) that enter the cells.

You're most at risk of psittacosis if you own a pet bird. Your occupation may also expose you to infection. You may get psittacosis without such obvious risk factors — the disease can infect you from exposure to infected birds or their droppings during visits to zoos, pet shops, etc.

Occupations at risk of psittacosis include:

  • Veterinarians and other staff at veterinary hospitals
  • Laboratory workers
  • Farmers and poultry farm workers
  • Workers in bird quarantine centers
  • Zoo employees

Bird owners, aviary and pet shop employees, poultry workers, and veterinarians are at high risk for this zoonotic disease. Eating or cooking poultry does not cause psittacosis.

Psittacosis is a variable disease. The symptoms vary from almost none to severe illness, including pneumonia and systemic disease. The disease usually begins 5 to 14 days after exposure. It starts as an upper respiratory infection with fever, headache, and muscle aches and pains.

Frequent symptoms of psittacosis in humans include:

As the disease progresses, you may develop pneumonia. Your doctor may hospitalize you for treatment. The monitoring may show a slow pulse, respiratory failure, and metabolic abnormalities. Other complications that happen sometimes include:

  • Myocarditis (inflammation of the heart)
  • Pericarditis (inflammation of the pericardium, the membrane covering the heart)
  • Encephalopathy (dysfunction of the brain)
  • Respiratory failure needing intensive care
  • Hepatitis (liver damage)
  • Arthritis (inflammation of the joints)
  • Sepsis (widespread infection in the blood and other tissues)

With modern treatment, the death rate is less than 1%.

Psittacosis in humans manifests as a respiratory illness. Your doctor may suspect this diagnosis if you have a pet at home or exposure at your workplace. Working at a place close to a farmer's poultry market and similar establishments can also expose you to psittacosis even if your own work has nothing to do with birds.

Your doctor will find signs of lung infection when they examine you. Laboratory tests will also show bacterial infections. Your doctor may ask for X-rays of the chest or a computed tomography scans (CT scan), which can help diagnose this disease.

Growing the germs in the laboratory is considered a definite diagnosis of an infectious disease. It's not used in psittacosis because the germ is highly infectious and difficult to grow, and the results may take weeks. Serological tests can diagnose this infection but are not available everywhere and take time, delaying treatment. DNA tests like next-generation sequencing (NGS) are quick. Your doctor can start treatment rapidly. 

Tests for psittacosis are not available everywhere. State or federal public health laboratories often have diagnostic facilities for this disease. Your doctor may have to send your samples to the Centers for Disease Control and Prevention (CDC) for processing.

Your doctor will prescribe a tetracycline antibiotic like doxycycline to treat psittacosis. Quinolone antibiotics like levofloxacin and moxifloxacin and macrolides like azithromycin are other effective medicines. Fever usually subsides in one to four days. Your doctor may prescribe more medications for severe pneumonia or complications. 

The disease is rare in children but presents special challenges in its treatment. Children can't take quinolone medications. Your doctor will prescribe azithromycin if your child is less than 8 years old. They may prescribe doxycycline for older children. Almost all children recover.

Your doctor may hospitalize you if you're very sick. Respiratory failure may need intensive care and mechanical ventilation. Nervous system complications like meningitis are challenging to treat. The medicines that are effective against psittacosis don't reach the brain. 

Pets provide joy and companionship, but they do carry the risk of zoonoses. A few precautions will keep you and your family safe:

  • Avoid contact with saliva, droppings, urine, mucus, blood, and other body fluids of your pet, especially if you know they're infected.
  • Wash your hands carefully after being around your pet, even if you haven't touched them. 
  • Wear protective gear when handling pet habitats like pet coops and cages and pet food and water dishes.
  • Clean your pets' cages frequently to prevent the collection of dried feces that become airborne. 
  • Outbreaks have happened from wild birds in workplaces. Everyone should refrain from feeding pigeons and other birds.

People with psittacosis don't need isolation. This disease does not spread person-to-person. Many infected birds appear well but can transmit infection. If you have a pet bird that may have infected you, a veterinarian should treat them.