Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content +++ Key Features +++ Essentials of Diagnosis ++ Fever, chills, and cough; headache common Atypical pneumonia with slightly delayed appearance of signs of pneumonitis Contact with infected psittacine bird 7–15 days previously Isolation of chlamydiae or rising titer of complement-fixing antibodies +++ General Considerations ++ Etiologic agent is Chlamydia psittaci, a bacterium Infection is acquired by inhaling dried secretions from infected psittacine birds (parrots, parakeets, pigeons, chickens, ducks, and many others), which may or may not appear ill The incubation period is 6–19 days Exposure history may be difficult to obtain if the patient acquired infection from an illegally imported bird +++ Clinical Findings +++ Symptoms and Signs ++ The onset is usually rapid, with fever, chills, myalgia, dry cough, and headache Signs include temperature-pulse dissociation, dullness to percussion, and rales Pulmonary findings may be absent early Dyspnea and cyanosis may occur later Culture-negative endocarditis +++ Differential Diagnosis ++ Other atypical pneumonia (eg, viral pneumonia, Mycoplasma pneumoniae, Chlamydophila pneumoniae) Unusual presentations of typical bacterial pneumonia Hypersensitivity pneumonitis Other cause of culture-negative endocarditis +++ Diagnosis +++ Laboratory Tests ++ The diagnosis is usually made serologically by a rise in titer of complement-fixing antibody in convalescent versus acute serum Antibodies appear during the second week Antibody response may be suppressed by early chemotherapy +++ Imaging Studies ++ The radiographic findings are those of atypical pneumonia, which tends to be interstitial and diffuse in appearance, though consolidation can occur Psittacosis is indistinguishable from other bacterial or viral pneumonias by radiography +++ Treatment +++ Medications ++ Tetracycline, 500 mg every 12 hours intravenously or orally, or doxycycline, 100 mg every 12 hours orally, for 14–21 days Erythromycin, 500 mg every 6 hours orally, may also be effective +++ Outcome +++ Complications ++ Endocarditis, hepatitis, and neurologic complications may occasionally occur Severe pneumonia requiring intensive care support may also occur Fatal cases have been reported +++ Prevention ++ Traceback of infected birds to distributors and breeders often is not possible because of limited regulation of the pet bird industry +++ Prognosis ++ Excellent with early treatment +++ When to Refer ++ Early referral to an infectious disease specialist for severe disease may aid in management +++ When to Admit ++ Respiratory compromise Rapidly deteriorating clinical course Suspected or proven endocarditis +++ Reference + +Lagae S, et al. Emerging Chlamydia psittaci infections in chickens and examination of transmission to humans. J Med Microbiol. 2014 ... GET ACCESS TO THIS RESOURCE Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. Access My Subscription GET ACCESS TO THIS RESOURCE Subscription Options Pay Per View Timed Access to all of AccessMedicine 24 Hour $34.95 (USD) Buy Now 48 Hour $54.95 (USD) Buy Now Best Value AccessMedicine Full Site: One-Year Individual Subscription $995 USD Buy Now View All Subscription Options