Psittacosis (parrot fever): symptoms, causes and treatment

Psittacosis is a bacterial infection caused by Chlamydia psittaci, a bacterium that normally infects birds. It is a different organism from the one that causes the sexually transmitted infection called chlamydia. UKHSA says that not all birds have symptoms when infected, but they can still transmit infection.

In people it is mainly a respiratory illness. UKHSA describes it as an acute respiratory disease. It is uncommon: UKHSA says usually fewer than 10 PCR-confirmed cases are reported each year in England, though case numbers can vary and some infections are mild or are never specifically diagnosed.

UKHSA explains that transmission from birds to humans occurs mainly through inhalation of infected respiratory particles, or dust contaminated with faeces or respiratory secretions. Direct oral contact with an infected bird and handling of infected birds' plumage and tissues are alternative routes.

Those at greatest risk are bird fanciers and owners of pet birds, along with pet shop employees and others whose job exposes them, such as poultry slaughterhouse workers, veterinarians and wildlife and zoo workers. UKHSA stresses that because infection can follow brief exposure to infected birds or their dried droppings, people with no known occupational or recreational risk can also be infected.

UKHSA says the incubation period is between 1 and 4 weeks and that people typically present with non-specific flu-like symptoms. A clinical reference page written for UK doctors describes a wide range, but the core picture is consistent: a fever and cough that can seem like flu or a chest infection and that may follow a few weeks after contact with birds.

• Fever and chills.

• Headache.

• Muscle aches.

• Cough, sometimes with breathlessness.

UKHSA says human infection may often be mild, but it can lead to severe pneumonia and respiratory failure, especially if untreated in elderly or immunocompromised people. Very rarely it may lead to inflammation of other organs, including the heart, liver or brain.

See a GP promptly if you have flu-like symptoms or a persistent cough after contact with birds, and mention the bird exposure. If you become very breathless, confused, or are struggling to speak in full sentences, call 999 or go to A&E; that picture needs urgent assessment whatever the cause.

UKHSA guidance for clinicians says they should consider psittacosis in patients with appropriate symptoms who have a history of exposure to birds or to environments contaminated with bird droppings, and should consider testing in severe undiagnosed pneumonia even without known bird exposure. Diagnosis is confirmed by molecular (PCR) testing of respiratory samples, available from the UKHSA respiratory and vaccine preventable bacteria reference unit, and some NHS trusts have in-house PCR testing.

UKHSA says antibody testing of paired blood samples has historically been used but is no longer considered best practice. This is a reason to tell the clinician about any bird contact: it triggers the right test.

UKHSA says cases can be treated with appropriate antibiotics. A UK clinical reference page for doctors, last updated in 2014 and flagged as not recently reviewed, states that tetracyclines such as doxycycline are the usual first-line choice and that treatment is normally given for 2 to 3 weeks to reduce the risk of relapse. Your doctor will decide which antibiotic suits you.

People who are severely unwell with pneumonia are treated in hospital, sometimes needing oxygen or other respiratory support, in line with how other severe pneumonias are managed.

UKHSA says prevention relies on reducing the accumulation of infected droppings, feathers and other secretions to prevent infected dust, and on good ventilation where birds congregate. It points to the Health and Safety Executive for guidance on managing the risk in workplaces, and says it is good practice to keep wild bird feeding stations well maintained.

Assessment normally starts with a GP or NHS 111, with chest X-ray, blood tests and respiratory sampling arranged through the NHS. Reference laboratory testing is provided through UKHSA. Private GP services can also prescribe antibiotics, but anyone with significant breathlessness should go through urgent NHS care.