Persisting predominant clinical CC87 Listeria monocytogenes in China: evolutionary dynamics and diversification

Listeriosis, caused by Listeria monocytogenes (L. monocytogenes), is a severe foodborne infection linked to neonatal meningitis and high mortality. However, long-term epidemiological trends in China remain undercharacterized. We conducted a 60-year literature-based review of listeriosis cases in China (1961-2020) and integrated publicly available genomic data from Chinese clinical L. monocytogenes isolates to explore molecular epidemiology and evolutionary patterns. Our analysis identified three distinct epidemiological periods: Sentinel (-1999), Growth (2000-2009), and High-Incidence Plateau (2010-2020). Overall, the case fatality rate was high (24.3%), particularly in perinatal cases (33%), with significant pregnancy complications, including miscarriage (35%) and neonatal mortality (27.5%). Spatial clustering was observed in economically developed regions, likely reflecting improved surveillance and increased consumption of ready-to-eat foods. Genomic analysis revealed that the CC87 clone, carrying both LIPI-1 and LIPI-4, forms a distinct evolutionary branch in China. Bayesian phylodynamic analysis estimated that the global CC87 lineage originated around 1967 (median MRCA), with a gradual increase in effective population size from the late 1980s, indicating prolonged national expansion and recent stabilization. Phylogenetic and genomic analyses revealed weak phylogeographic structure within China, with extensive inter-provincial mixing and minimal local clustering. These findings suggest widespread nationwide circulation, frequent cross-regional transmission, and ongoing diversification of CC87. By integrating epidemiological and genomic data, our study provides a comprehensive overview of listeriosis dynamics in China, highlighting hypervirulent clones as critical targets for public health interventions and informing One Health-oriented prevention strategies.