China's psittacosis knowledge gap: A scoping review calls for coordinated action

A Disease Resurging Faster Than Understanding

Psittacosis—a bacterial pneumonia transmitted from birds to humans—is experiencing a notable resurgence in China. Once rarely reported, the disease now generates dozens of publications annually, driven by expanded use of metagenomic next-generation sequencing (mNGS) in clinical settings and increased diagnostic awareness. Yet this surge in research reveals a paradox: the more comprehensively scientists investigate, the more evident become the significant gaps in current knowledge.

The Scope of the Problem

A collaborative research team from Shanghai Jiao Tong University School of Medicine and the Chinese Center for Disease Control and Prevention conducted the most comprehensive scoping review of psittacosis in China to date, analyzing 424 studies published between 1985 and 2025. The review presents a sobering picture: psittacosis is epidemiologically substantive, clinically serious, and chronically underserved by institutional resources and public health infrastructure.

Clinical Reality and Diagnostic Bottlenecks

Cases predominantly affect middle-aged and older adults with documented exposure to birds or poultry—ranging from pet parrot owners to slaughterhouse workers. Disease incidence peaks during winter and spring months, though notable regional variation exists across China. Pneumonia is the dominant clinical presentation, with severe cases progressing to acute respiratory distress syndrome and multi-organ failure.

Although tetracyclines are consistently effective once Chlamydia psittaci is identified, patients frequently receive incorrect empirical therapy initially because psittacosis symptoms are non-specific and conventional culture methods fail to detect the pathogen. The diagnostic landscape is evolving: mNGS has become the most frequently used confirmatory tool in recent Chinese hospital reports, delivering results within 24 hours in some centers. However, this technology remains expensive, quality-control standards vary widely, and comparisons with targeted PCR remain limited.

Knowledge Gaps in Surveillance and Molecular Epidemiology

The molecular epidemiology of Chlamydia psittaci in China remains inadequately characterized. Most studies employ single-gene (ompA) genotyping, providing limited insight into strain relationships and outbreak sources. Whole-genome sequencing—essential for tracing transmission linkages between avian and human cases—is rarely applied. Compounding this, China currently lacks a unified national surveillance framework for psittacosis. Public health responses remain largely reactive, triggered only when outbreaks occur, with fragmented coordination among health, agriculture, and market-regulation authorities.

Priority Actions for Reform

The authors identify six essential priorities: strengthening epidemiological infrastructure for systematic case detection and tracking; expanding molecular surveillance with whole-genome sequencing; standardizing diagnostic pathways across hospitals; building comparative treatment evidence; reinforcing prevention at the human–animal interface; and establishing formal One Health coordination across sectors.

From Recognition to Action

The six priorities outlined—strengthening epidemiological infrastructure, expanding molecular surveillance with whole-genome sequencing, standardizing diagnostic pathways, building comparative treatment evidence, reinforcing prevention at the human–animal interface, and establishing formal One Health coordination—represent concrete steps toward closing critical knowledge gaps. China's extensive ornamental bird trade, intensive poultry production systems, and dense urban populations create a persistent reservoir for disease circulation. The recent inclusion of psittacosis on the national zoonotic disease list marks institutional recognition of the threat, but recognition alone is insufficient. Translating this acknowledgment into systematic prevention and control requires sustained investment in diagnostics, surveillance infrastructure, and cross-sectoral coordination. The scoping review provides both a sobering assessment of current shortcomings and a roadmap for reform—one that demands urgent implementation.