Psittacosis. A diagnostic challenge.

In the absence of recognized pneumonitis, psittacosis is unlikely to be considered as a cause of infection in patients with febrile illnesses. To identify findings useful in the diagnosis of psittacosis, the clinical and roentgenographic characteristics of 46 cases that occurred in two outbreaks among workers in turkey processing plants were reviewed. Headache (96% of patients), chills (93% of patients), and fever (89% of patients) were the most common symptoms; a nonproductive cough occurred in 65% of patients. Rales or rhonchi were detected in only six (18%) of 33 patients examined, but 21 (72%) of 29 patients receiving a chest film had roentgenographic evidence of pneumonia. We conclude that few diagnostically useful symptoms or signs occur in patients with psittacosis but that roentgenographically confirmed pneumonitis may occur commonly in patients with little clinical evidence of pneumonitis. A history of exposure to birds, in an individual with a flu-like illness, appears to be the single best clue to the diagnosis of psittacosis.