On October 30, 2014, the Hong Kong Centre for Health Protection (CHP) recorded a sporadic case of psittacosis affecting a 57-year-old man with underlying illness.

Thick-billed Parrot Image/Ltshears
Thick-billed Parrot

He presented with fever, mild cough and myalgia since October 10. He was admitted to a public hospital on October 22 and required intensive care support initially. His chest X-ray showed signs of pneumonia. His tracheal aspirate was later tested positive for Chlamydophila psittaci by Polymerase Chain Reaction (PCR) on October 30.

His condition was stable and he was discharged on November 4. He had no recent travel history. He did not keep birds at home and he had no contact history of birds or bird droppings. His home contacts were all asymptomatic. Investigation is on-going.

Most wild and domestic birds can be natural reservoirs of the causative bacteria,Chlamydophila psittaci, however parrots, parakeets, and cockatiels are among the birds most commonly implicated in human infection.

The vast majority of cases of psittacosis are a direct result of human exposure to pet birds, either as owners or pet shop employees. The remainder of human cases is due to occupational exposure; turkey processing workers, vets, and zoo workers to name a few.

In the bird, infection may not become apparent unless resistance is compromised through conditions like crowding, transport, deficiencies in nutrition or other stressors.

The infection in the bird is mostly gastrointestinal and respiratory with the bird showing the following symptoms: diarrhea, nasal discharge, fever and discharge from the eyes.

The organism is shed in the liquid feces or nasal discharge of a sick bird. Even healthy birds can be carriers of psittacosis and may shed the organism intermittently.

Here it can contaminate the environment, the bird’s cage and the feathers. As the feces dries, the bacteria become airborne from the motion of the feathers and this is where humans can get infected.

The aerosolized, airborne particles are very small and do not settle easily and remain suspended in the atmosphere for long periods of time.

The infection in people can range from an inapparent illness to a systemic disease and severe pneumonia with some fatalities reported.

The onset of disease may be fever, headache, body aches, cough and shortness of breath. The illness is usually self-limiting (up to 2 weeks).

More severe disease may show diarrhea, vomiting and enlarged liver and spleen. The organism can affect some organ systems other that the respiratory. Cases of endocarditis, arthritis and hepatitis have been seen.

Psittacosis is treatable with doxycycline. The fatality rate of patients treated with antibiotics is very low, less than 1%.

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