The bacterium Chlamydia psittaci is similar to a bacteria (it responds to antibiotics) and a virus (it will only grow on a tissue culture, not on bacterial media). C. psittaci has ability to cause disease in humans, other mammals and birds. In psittacines Chlamydia psittaci is called psittacosis, in other birds it is named ornithosis, in humans it can be called either parrot fever or chlamydiosis.
Among birds Chlamydia psittaci infects wild and domestic birds and poultry. The time between exposure and the onset of illness in caged birds ranges from three days to several weeks. Sick birds show signs of:
How a bird manifests its exposure to this disease depends on host susceptibility and the virulence of the strain to which the bird was exposed. Some birds, because of their genetic resistance, are less likely to become ill and consequentially will develop into a "carrier". Carriers are birds that appear healthy and do not show symptoms now but can transmit the disease to other birds, mammals or people. Pigeons, doves, budgerigars, cockatiels, cockatoos, herons, gulls, hawks and some sylvatic species. Species with a low natural resisitance and high susceptiblility include some parrots species, rosellas, lorikeets, neophemas, mynahs, and canaries.
Infrequently psittacosis will affect the central nervous system particularly in Amazons, African Greys and Cockatoos. Tremors, shaking, head twisting and convulsions may be the only symptoms. Cockatiels can develop paralysis of the limbs and dark, tarry stools. Cockatiels and neophemas with low-grade infections may develop an eye disease resembling a sty.
In humans the incubation period is 5 - 19 days. Clinical signs include:
Pneumonia is often evident upon chest x-ray. Endocarditis, hepatitis and neurologiic complications may occur. Severe phneumonia and fatal cases have been reported.
Risk groups include bird owners, pet shop employees, veterinarians and their staff, and poultry processing plants and personel. Human to human transmission is possible, but rare. Psittacosis is a reportable disease in most states, including Florida.
The organism is shed in the nasal secretions and in the stool of an infected bird, a recovering bird or a carrier. Once outside the body, the organism can survive for long periods of time in the form of dried dust particles. Infection is acquired by inhaling these dried secretions. Fecal and oral contaminations are especially significant under crowded conditions or in nest boxes of infected birds. As a general rule, inhaled Chlamydia will usually cause severe disease, while ingested Chlamydia will create carriers.
Most vets use tetracycline or a Vibramycin derivative intravenously or intramuscularly to treat both symptomatic and carrier birds. Blood levels of tetracycline can be enhanced by citric acid in the birds' drinking water. Supportive care including heat, isolation and sanitary conditions as well as providing lactobacillus, and antifungal medications are essential to the bird.
Control is best accomplished by isolation of infected birds, and to separate birds in breeding facilities according to their susceptibility. Quaternary ammonium compounds inactivate Chlamydia and should be used to clean cages, wet-mop surrounding areas and to spray the area for disinfection. Birds that have this disease or are being treated can be reinfected immediately since there is no immunity to it.
© 2001 -2004 by Talking Green Parrot Aviary
