Patients respond well to antibiotic treatment with resolution of symptoms within 24 to 48 hours, although there is the potential for relapse from persistent infection. Severely ill patients have a good prognosis if there are no complications. Pulmonary, cardiac, and intravascular complications can be life threatening.[1]Schlossberg D. Chlamydophila (chlamydia) psittaci (psittacosis). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and practice of infectious diseases, 6th ed. Philadelphia, PA: Churchill Livingston; 2005:2256-8. Mortality can be as high as 20% in untreated patients.[1]Schlossberg D. Chlamydophila (chlamydia) psittaci (psittacosis). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and practice of infectious diseases, 6th ed. Philadelphia, PA: Churchill Livingston; 2005:2256-8.[13]National Association of State Public Health Veterinarians (NASPHV). Compendium of measures to control Chlamydia psittaci infection among humans (psittacosis) and pet birds (avian chlamydiosis). 2017 [internet publication].
http://www.nasphv.org/Documents/PsittacosisCompendium.pdf
Fetal mortality among pregnant women is very high.[31]Katsura D, Tsuji S, Kimura F, et al. Gestational psittacosis: a case report and literature review. J Obstet Gynaecol Res. 2020 May;46(5):673-7.
http://www.ncbi.nlm.nih.gov/pubmed/32077210?tool=bestpractice.com
Resistance to antibiotics has been reported only anecdotally.[29]Binet R, Maurelli AT. Frequency of development and associated physiological cost of azithromycin resistance in Chlamydia psittaci 6BC and C. trachomatis L2. Antimicrob Agents Chemother. 2007 Dec;51(12):4267-75.
http://aac.asm.org/content/51/12/4267.full
http://www.ncbi.nlm.nih.gov/pubmed/17908942?tool=bestpractice.com
Due to the limited availability of cultures for testing, it remains unclear whether treatment failures are due to resistance or progression of disease from more virulent strains or host factors.