http://www.nwhc.usgs.gov/publications/field_manual/chapter_10.pdf
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.
Species Affected
Chlamydiosis was first recognized as an infectious disease affecting parrots, parakeets, and humans involved in the international parrot trade in the late l920s to l930s. Chlamydiosis
has since become known as a serious disease of domestic turkeys in the United States, of domestic ducks and geese in central Europe, and as a common infection of domestic
and feral pigeons worldwide. The feral city pigeon is the most common carrier of Chlamydia sp. within the United States.
Chlamydial infections have been reported from at least 159 species of wild birds in 20 orders, but most isolations have been made from six groups of birds (Figure 10.1). Psittacine
birds such as parakeets, parrots, macaws, and cockatiels are most commonly identified with this disease, while among other caged birds Chlamydia sp. occurs most frequently in pigeons, doves, and mynahs. Waterfowl, herons, and pigeons are the most commonly infected wild birds in North America (Figure 10.2). Chlamydiosis also occasionally
infects gulls and terns, shorebirds, songbirds, and uplandgamebirds.
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 shorebirdsin 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.
