Psittacosis or parrot fever

Psittacosis is also known as parrot fever. In pigeons and other bird species, the disease is also known as ornithosis. Psittacosis is a disease that is caused by the Chlamydia psittaci bacterium. This is a "gram negative" bacterium that can only replicate in cells in the form of a reticulate (net-shaped) body. Chlamydophila psittaci survives in the environment in the form of the elementary body. In this form, the bacterium can survive for a long time while also remaining infectious.

Parrot fever in birds

In birds, psittacosis occurs primarily in parrot-like birds (psittaciformes) and pigeons. The symptoms vary from extremely mild to serious, with discharge from the eyes and nose, lack of appetite and diarrhoea. Asymptomatic carriers also occur among the bird population. These are animals that do in fact carry the bacterium but do not show symptoms. When under stress or another cause of reduced resistance, the birds may become sick and excrete bacteria, with the result that they are infectious for other birds and for humans. Chlamydophila psittaci is excreted via faeces and secreted through eye or nasal discharge. The treatment for birds is by administering antibiotics over a longer period. Psittacosis in birds is a notifiable disease.

Parrot fever in humans

Psittacosis is a zoonosis. This is a disease that can be transmitted from animals to humans. Human-to-human transmission occurs only infrequently. However, the disease can spread more easily among birds, and birds are usually the cause of human psittacosis. Humans are usually infected through inhalation of small particle aerosols contaminated with Chlamydophila psittaci. The progression of the disease is usually asymptomatic or with limited flu-like symptoms. In certain cases, however, the disease is accompanied by high fever, severe headache and muscle pain and pneumonia. Hospitalisation may be necessary.

Consult your GP

Do you believe you are showing symptoms? Then consult your GP. If psittacosis is diagnosed, treatment consists of the administration of antibiotics.

Transmission of psittacosis

Psittacosis occurs primarily in birds, mainly in parrot-like birds (psittaciformes) and pigeons. Birds may also be asymptomatic carriers, with the result that it is difficult to distinguish infected birds from uninfected. Chlamydophila psittaci remains infectious in bird faeces for a long time, even if the faecal matter has dried out. Humans become infected through contact with a diseased bird or through contact with dried bird faeces.


In cases of psittacosis in humans, there is virtually always a link to birds. In humans, the disease is notifiable in Group C. The disease is also notifiable in birds.

What does Wageningen Bioveterinary Research do?

Wageningen Bioveterinary Research conducts laboratory diagnosis on samples supplied by the NVWA (Dutch Food and Consumer Product Safety Authority). The NVWA takes samples in suspect cases and on import (quarantine facilities). In the event of suspect cases, this is usually a case of human psittacosis. Birds are sampled in order to trace the source of the infection. It is important to trace other people who might have become infected and in order to prevent others from becoming infected through contact with these birds. At Wageningen Bioveterinary Research, diagnosis of psittacosis is conducted by means of an immunofluorescence assay (IFA) and by means of a PCR test. The IFA is conducted on organ material. The PCR can be carried out on a cloaca swab or on faecal matter.