Psittacosis is a worldwide zoonosis (i.e. a disease that can be transmitted between animals and humans) caused by the bacterium Chlamydia psittaci, that is common in certain types of birds. Humans get infected through exposure to droppings and secretions of infected birds. Due to under-diagnosis and under-reporting, the incidence of the disease is underestimated.

What is psittacosis?

Psittacosis is a worldwide zoonosis transmitted from birds to humans, caused by the bacterium Chlamydia psittaci. The infection is widespread in birds, particularly in Psittacines (parrots, callopsittes and parakeets), but also in turkey, duck and pigeon farms.

A study in poultry farms in 2012 showed that Chlamydia psittaci is omnipresent in Belgium.


Human exposure can be professional (bird breeders, veterinarians, poultry slaughterhouse workers,…) or recreational (Psittacine owners, pigeon fanciers, visitors of bird shows, …). The disease occurs in sporadic forms or in small epidemics (e.g. during bird shows).

The most common way someone gets infected is by breathing in the dust from dried droppings and secretions from infected birds. Less commonly, birds infect people through bites and beak-to-mouth contact.


The clinical picture may range from asymptomatic infection to atypical pneumonia, the most suggestive form of infection, or even systemic involvement leading to death. The case fatality rate is 10-20% without treatment but less than 1% with adequate antibiotic therapy (Doxycycline).

The disease is often not recognized or patients do not consult a doctor because of mild symptoms, and under-diagnosis and under-reporting of the disease is most likely.

Sciensano is responsible for the epidemiological surveillance of psittacosis in Belgium. For this purpose, we collect data through different networks, which allow to describe the occurrence of the disease, follow-up trends over time and identify possible risk factors for infection.

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