Psittacosis, also known as parrot disease, ornithosis, and chlamydiosis, is a rare zoonotic disease caused by the bacterium Chlamydia psittaci, found in the dried secretions and droppings of wild and domestic birds and poultry. Natural infection occurs by inhalation of contaminated dust or aerosols, and as an agent of bioterrorism this would be the most likely method of dispersal.

Psittacosis may progress to include hepatic and/or splenic enlargement, cervical lymphadenopathy, urticaria, subungual hemorrhage, erythema nodosum, and erythema marginatum. Cardiac manifestations may include relative bradycardia, pericarditis, and myocarditis.

Rarely, severe psittacosis can be fatal (less than 1% with proper antibiotic treatment). Mortality rates in a bioterrorism event may be higher due to a higher initial exposure.

The incubation period of psittacosis is 5-15 days. Transmission occurs through inhalation of aerosolized urine, dried droppings, or secretions from infected birds, which may lodge in feathers or reside in nasal discharges and can stay dormant for months. It may also be transmitted via a bird bite, bird handling, or mouth-to-beak contact. Person-to-person transmission is rare but has been documented.

C. psittaci is most commonly found in pet birds (eg, parakeets, macaws, parrots, cockatiels), pigeons, ducks, chickens, and turkeys, which are often asymptomatic. Infected birds with symptoms present with diarrhea, shivering, sleepiness, anorexia, and breathing difficulties.

There is no vaccine for psittacosis.

Fewer than 50 cases of psittacosis are reported in the United States each year. However, the incidence rate varies due to outbreaks and may be low due to misdiagnosis and underreporting.

Poultry farm workers, abattoir workers, poultry processing plant workers, duck and turkey hunters, veterinarians, zoo keepers, pet shop workers, people exposed to bird nesting areas (eg, bell towers, etc), and people who keep birds as pets are at higher risk for infection.

Note: Wear protective (HEPA or N-95 filter) masks to prevent natural infection and inhalation of aerosolized psittacosis. Surgical masks may also be helpful. Masks and gloves should be worn when exposed to infected wild, domestic, and pet birds. Infected birds should be isolated and quarantined and may present with diarrhea, conjunctivitis, and anorexia, although they can also appear healthy. Practice proper birdcage hygiene and ventilation; avoid overcrowding birds. Avoid dry removal of dry bird droppings; moisten with disinfectant (1 part bleach in 9 parts water) prior to removal.