Psittacosis
Chlamydia psittaci
Profile
In birds, parrot disease causes coughing, emaciation, ruffled feathers, diarrhoea, eye and nasal discharge and is often fatal. In humans, it can cause pneumonia. The pathogen is the bacterium Chlamydia psittaci from the Chlamydia group.
The disease is notifiable as soon as psittacosis is detected in parrots and parakeets (Psittaciformes). Psittacosis is a zoonosis (i.e. a disease that can be transmitted from animals to humans), but overall it is very rare. If birds of other species are infected with C. psittaci, this is known as ornithosis. An infection caused by other chlamydiae, such as C. avium or C. gallinacea, is referred to as avian chlamydiosis.
Symptoms
Symptoms in the bird include pneumonia, coughing, emaciation, ruffled feathers, diarrhea, ocular and nasal discharge. Death may occur after a few days to several weeks, or the disease may progress to a chronic form in which the birds appear to recover but continue to shed pathogens. In humans, febrile general symptoms and subsequent pneumonia usually occur.
Prevention
As a preventative measure, birds must be quarantined and tested for Chlamydia after purchase. The usual hygiene measures for handling animals must be observed. Be careful with direct contact with bird faeces. It is recommended to wear a protective mask, gloves and protective clothing when handling infected birds. Psittacosis is a notifiable animal disease under the Animal Health Act. Direct vaccination against the pathogen is not possible.
In Austria, psittacosis (in parrots and parakeets) is a notifiable disease under Section 36 of the Animal Health Act (TGG). Any suspected case of psittacosis must be reported to the official veterinary officer. Where appropriate clinical symptoms are present and C. psittaci has been diagnostically confirmed, the official veterinary officer will decide whether quarantine or treatment is necessary, depending on the course of the disease.
In 2025, 38 molecular biological tests were carried out on various birds (chickens, pigeons, parakeets, parrots, other ornamental birds, etc.) – one of which tested positive for C. psittaci.
Technical information
Chlamydia psittaci is obligately intracellular and occurs in various forms: as elementary bodies (infectious form), as intermediate bodies and as reticular bodies. The individual species of Chlamydia show a high degree of host specificity: C. psittaci is found mainly in psittacines, small ruminants and humans; C. abortus in sheep and goats; and C. trachomatis in humans.
In terms of differential diagnosis, infections such as avian influenza and Mycoplasma pneumoniae should be considered.
Transmission
All secretions and excretions are infectious. The pathogen is usually acquired via droplet transmission through the inhalation of infectious faeces, dust or aerosols. With this mode of transmission, the upper respiratory tract is the most likely point of entry. Transmission can also occur via contact infection or smear infection, although almost exclusively in people who have close contact with infectious animals. In humans, infection usually occurs aerogenically through the inhalation of infectious faecal particles and dust. This usually results in general symptoms accompanied by fever, followed by pneumonia.
The incubation period is 3–29 days, but can be as long as 100 days.
Symptoms
Symptoms in birds include pneumonia, coughing, weight loss, ruffled plumage, diarrhoea, and discharge from the eyes and nose. The disease leads to death within a few days to weeks, or progresses to a chronic form in which the birds appear to recover but continue to shed the pathogen. In humans, the disease usually presents with generalised symptoms including fever, followed by pneumonia.
Diagnostics
Suitable sample materials are
- Organs
- faeces, faecal swabs
- cloacal swabs
Laboratory diagnosis is made by direct detection of Chlamydia DNA and, in positive cases, Chlamydia psittaci differentiation from other species using molecular biological methods (PCR). At necropsy of birds, swelling of the spleen and liver in particular are important indications of psittacosis, so this must always be considered in the differential diagnosis in the event of corresponding changes. The cultivation of C. psittaci is difficult and is reserved for a few specialised laboratories. It is not possible to make a diagnosis in birds by detecting specific antibodies in serum; this is only possible in ruminants, pigs, horses or small animals.
Contact
Institut für veterinärmedizinische Untersuchungen Mödling
- vetmed.moedling@ages.at
- +43 50 555 38112
-
Robert Koch-Gasse 17
2340 Mödling
Last updated: 25.06.2026
automatically translated