Avian Chlamydiosis (Psittacosis) Epidemiology

The incidence and distribution in Montana and elsewhere, along with the information regarding the spread of the disease.

Birds are the reservoir host. Carriers of the disease may and may not show symptoms. Imported birds are the most common source of infection.

Transmission - Bird to Bird
The bacteria are transmitted from bird to bird via inhalation from dried droppings, secretions and feather dust from infected birds.

Transmission - Bird to Human
People get the disease by breathing the dust from dried droppings in birdcages, or by handling infected birds in slaughterhouses. The bacteria in the environment are very resistant: waste material in birdcages can be infectious for weeks. The incubation period for humans is 1 to 4 weeks. In humans, pet bird owners, pet shop employees and veterinarians are at greatest risk for exposure. Occupational exposure also can occur in poultry processing facilities and laboratory settings.

Distribution
Among free-living birds, avian chlamydiosis has been found worldwide in the feral pigeon, in gulls and fulmars on islands of coastal Great Britain, in waterfowl and shorebirds in the Caspian Sea, and in herons, waterfowl, gulls, and doves in the United States. Infected parrots and parakeets have been found throughout the tropics and Australia.