No 11 - 2020

Ornithosis 2017-2019

Ornithosis 2017-2019

In the 2017-2019 period, a total of 62 persons became infected with ornithosis, also known as parrot fewer.

Ornithosis is caused by the Chlamydia psittaci bacterium that transmits from birds to humans, but not between humans.

In humans, the condition initially presents as influenza-like symptoms; fever, myalgia and headache, in some cases combined with diarrhoea, nausea and vomiting. In some cases, a dry cough also presents, which may subsequently change into a cough with phlegm. Chest pain and difficulty breathing are also seen. In rare cases, the infection causes severe pneumonia and affects other organs (liver, spleen, heart, etc.). The risk of serious disease increases with age and immunodeficiency.

More than half of the cases recorded in the period had become infected in Denmark and had been in contact with either domestic or wild birds, including parrots, canaries, ducks, chickens and pigeons.

For more information about the monitoring and prevention of ornithosis, please see the annual report 2017-2019.

The number of ornithosis cases recorded in humans fluctuates from year to year. Thus, 2019 recorded more than twice as many cases as 2017 and 2018.


No ornithosis vaccine is available, but the condition can be managed effectively by antibiotics. For more information about ornithosis and prevention in humans, please see here (in Danish) 

Strengthened One Health cooperation

On 1 March 2019 as part of the national implementation of the One Health strategy against infectious diseases, the SSI and the University of Copenhagen jointly assumed responsibility for the Danish veterinary preparedness programme (Danish Veterinary Consortium, DK-VET) and for the provision of advisory services for the Danish Veterinary and Food Administration. This means that samples from sick people as well as from birds that are suspected carriers of C. psittaci have been submitted to the SSI for analysis and monitoring since 1 March 2019. Through this new focus and enhanced monitoring, it is expected that the number of diagnosed ornithosis cases in animals and humans alike will gain focus, as ornithosis is, in some cases, a relatively mild disease, which may also be difficult to diagnose.

Read more about the One Health activities and preparedness services here.

(C. Kjelsø, Department of Infectious Disease Epidemiology and Prevention, R. Føns Petersen, Ø. Angen, S. Uldum, Department of Bacteria, Parasites and Fungi, S. Kjær-Andersen, Animal Health, the Danish Veterinary and Food Administration).