Chlamydophila psittaci is a lethal intracellular bacterial species that causes endemic avian chlamydiosis, epizootic outbreaks in mammals, and respiratory psittacosis in humans. It can be transmitted through inhalation, contact, or ingestions among birds and mammals. It generally starts with flu-like symptoms and becomes a life-threatening pneumonia. Many stay dormant until activated by stress. Birds are great vectors of the disease since they are highly mobile and feed on infected animals. Previously it was classified as Chlamydia psittaci.
Infections in birds can be unapparent, severe, acute, or chronic. In birds it infects the mucosal epithelial cells and macrophages of the respiratory tract. Bacteria become localized in epithelial cells and macrophages of most organs, conjunctiva, and gastrointestinal tract. It can be passed in eggs after stress triggers the onset of symptoms.
It is a small bacterium that undergoes goes through several transformations during its life cycle. Since it exists as an elementary body (EB) is can survive outside of the host and gets into the lungs of the infected where it is taken up by an endosome. EBs are able to infect new cells in the same organism or in a new host. C. psittaci is broken into two parts, the elementary body which can infect but not replicate, and the reticulate body which can replicate but not infect.
Microimmunofluorescence and PCR tests can be used to confirm diagnosis. Tetracycline or macrolides are used to treat the condition and are given intravenously and orally. Treatment continues for 10-14 days after fever subsides.