Chlamydiosis is a very important and challenging disease of birds because it can be difficult to diagnose and treat, causes significant morbidity and mortality in birds, and is transmissable to humans. Illness caused by chlamydiosis can range from a life threatening system disease to an inapparent infection in a bird. The disease is caused by: Chlamydia psittaci, an obligate intracellular parasitic bacterial organism that contains both DNA and RNA.Chlamydiosis gained world wide prominance as a result of a widespread disease outbreak that occurred from 1929 to 1930 involving 12 countries. It was introduced into the United States by the importation of amazon parrots from South America.
This particular strain was very virulent, causing widespread economic losses to the poultry and duck industries and numerous human cases.
Chlamydia psittaci is found throughout the world infecting numerous wild birds. Many feral pigeons have a high incidence of infection with very low incidence of active disease.
Commercial turkeys are frequently infected with the organism resulting in a high incidence of human infection in the people who work in the processing plants. The reason that people who consume turkey don’t become infected is because cooking adequately destroys the organism.
Pet birds, especially budgies, cockatiels and lovebirds are frequently infected as a result of the intensive way that they are raised.
Although many parrots are infected with Chlamydia psittaci, they frequently do not exhibit clinical signs of illness but can transmit the organisim to humans and other birds. Stress – either from traveling, breeding, overcrowding or other disease – will cause an inapparent infection to become clinical, leading to signs of disease and shedding of the organism.
Nine different strains have been recognized in mammals. Five strains are known to infect birds: Psittacine, Pigeon I and II, Duck and Turkey. Each strain affects the species for which it is named as well as other host species. Severe disease often occurs when a strain occurs in a species in which it usually does not occur.
Psittacosis refers to clinical disease associated with Chlamydia psittaci in a bird of the order psittaciformes or parrots.
Ornithosis is clinical disease in birds other than parrots. The preferred term is Psittacosis rather than Ornithosis.
Although Chlamydia psittaci contains the nucleic acids DNA and RNA, it lacks the ability to survive and replicate on its own. It requires the use of certains cells in the body in order to survive and reproduce.
The next column on this subject will cover how it infects a cell, disease syndromes, diagnosis and treatment.