Free-ranging birds Captive birds Songbirds Free-ranging birds Captive birds Waterfowl Free-ranging birds Captive birds Herons and allies Free-ranging birds Captive birds Pigeons and doves Free-ranging birds Captive birds

Cause Chlamydiosis refers to an infection with organisms of the genus Chlamydia sp., which are bacteria that live within animal cells. Chlamydia psittaci is the species generally associated with this disease in birds. The severity of the disease differs by the strain of C. psittaci and the susceptibility of different species of birds. As a result, chlamydiosis may range from an inapparent infection to a severe disease with high mortality. The organism is excreted in the feces and nasal discharges of infected birds and can remain infective for several months. Infection commonly occurs from inhaling the bacteria in airborne particles from feces or respiratory exudates. Because of the organism’s resistance to drying, infected bird feces at roosts are especially hazardous.