Avian Chlamydiosis goes by other names including Chlamydiosis, Psittacosis, Parrot Fever, Chlamydia, Ornithosis Avian chlamydiosis (AC) is a zoonotic disease caused by Chlamydia, a bacterium that is commonly found worldwide in domestic and wild birds.
Depending on the immune status, the virulence of the strain, infectious dose and age of the bird, the disease can develop in an acute, subacute or chronic form.
In chickens, clinical signs of avian chlamydiosis are usually nonspecific and vary greatly in severity, depending on the bird’s age, immune status, and bacterial strain. Some birds may become infected and show no signs of illness.
Decreased appetite, serous or mucopurulent discharge from the eyes or nares, conjunctivitis, diarrhoea, and excretion of green to yellow-green urates in faeces are the most common clinical signs observed in chickens.
They may produce sparse, dark green droppings when birds are severely affected, followed by emaciation and dehydration, leading to death.
The transmission of Chlamydia between birds is mainly through the inhalation of contaminated faecal or feather dust.
As frequent carriers, exotic and wild birds act as reservoirs. Both subclinically infected and diseased birds can shed Chlamydia in their faeces.
The incubation period for avian chlamydiosis ranges from 3 days to several weeks for Chlamydia infection.
The use of a variety of available tests offered at veterinary diagnostic laboratories can confirm avian chlamydiosis. Bloodwork typically shows an elevated WBC with toxic changes in heterophilia/lymphopenia.
With increases in beta- and gamma-globulins, the total protein is elevated. Splenic and hepatic enlargement, with pulmonary congestion, are typically included in gross lesions.
Histologically, it is possible to see necrotizing splenitis, hepatitis, interstitial pneumonia and nephritis. With a Chlamydia PCR (DNA) probe and tissues, or by culture, the organism can be confirmed.
The treatment of avian chlamydiosis uses antibiotics. Doxycycline is the drug of choice and to be effective, usually requires long-term treatment.
During treatment, calcium should not be added to the diet, since it interferes with the drug’s effectiveness.