Evidence Hub

A case report of spherical pneumonia caused by Chlamydia psittaci infection

Li G, Li X, Feng Q, Wang X, Zhang X, Liu X

Frontiers in medicine, 2026

Abstract

Psittacosis is a zoonotic infectious disease caused by Chlamydia psittaci, typically transmitted from birds to humans. Its clinical manifestations are often subtle and non-specific, making it prone to being misdiagnosed as common community-acquired pneumonia. Round pneumonia (or spherical pneumonia) refers to a lung infection that appears as a round or oval density on computed tomography (CT). It is uncommon in adults. Spherical pneumonia specifically caused by Chlamydia psittaci infection is particularly uncommon. Here we report a case of a 43-year-old male who was admitted due to a 4-day history of fever. CT imaging revealed a solitary, round high-density shadow approximately 4 cm in diameter in the right lower lung, with clear margins and surrounding ground-glass opacity. The patient reported direct contact with ornamental parrots at a zoo 10 days before the onset of symptoms. The diagnosis of spherical pneumonia caused by Chlamydia psittaci infection was confirmed by targeted next-generation sequencing (tNGS). The patient's symptoms resolved following treatment with minocycline, and a follow-up CT scan 32 days later showed near-complete resolution of the lesion. This case demonstrates that Chlamydia psittaci can also produce a typical spherical lesion, thereby broadening the recognized imaging spectrum of this pathogen. When clinicians encounter a patient with imaging findings suggestive of spherical pneumonia and a history of bird exposure, Chlamydia psittaci infection…

How strong is the evidence?

Evidence Hub reads this as a case report, done in people. Its evidence level is 5 of 5 (Very low · case / narrative / animal / in vitro / in silico). Case reports, narrative reviews, and animal, cell or computer-model studies give the weakest evidence for human health.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

Read the paper

Related studies

Go deeper in Evidence Hub

Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.

Open this study Sign up free