Distribution and epidemiology of brucellosis in China.

Brucellosis is a globally important disease but its prevalence, distribution, and impacts remain poorly known in many countries. With the world's largest livestock population, and the second largest human population, the scale of brucellosis in China dwarfs that of the disease in other countries and is a preeminent One Health challenge. As a result, an overall understanding of the extent and burden of this disease and its impacts have been elusive and concerted efforts to reduce disease burden have been sporadic. Brucellosis is relatively common in many regions of China and infects humans and a range of livestock and wildlife. Reported human brucellosis cases increased from 45,046 in 2019 to 70,439 in 2023, reflecting the growing national burden. We reviewed the status of brucellosis in China from 1950 to 2025, with a particular focus on its distribution and molecular epidemiology of human and animal infections in the past decade. Human brucellosis cases have substantially and progressively increased since 1950, reflecting the growing national burden but also showing short periods of decline and then resurgence. For example, genetic analyses using MLVA and whole‑genome sequencing of Brucella isolates have identified Brucella melitensis (specifically the Eastern Mediterranean lineage and biovar 3) as the predominant genotype circulating in country, placing these samples into a global context. Moreover, some regions appear to be hotspots of disease, such as high disease incidence in animals in Inner Mongolia that corresponds with high infection rates in humans. Brucellosis also appears to be changing its distribution, expanding from northern pastoral and agricultural areas such as Inner Mongolia, Shanxi, Heilongjiang, Hebei, Jilin, and Shaanxi to more industrial provinces such as Henan, Guangdong, and Fujian, driven by livestock trade, transboundary spread, and north‑to‑south expansion. Notably, novel transmission routes have become evident that are not associated with occupational exposure. Furthermore, brucellosis is increasingly being found in wildlife, with the potential for cross-species transmission, unique strains, and additional host species that may remain to be discovered. Finally, we discuss vaccination, disease control strategies, and the comprehensive animal and public health measures that are needed to reduce brucellosis prevalence in China. Vaccination faces particular challenges due to a scarcity of efficacy studies. These findings directly impact control strategies by highlighting the need for region‑specific vaccination policies, enhanced surveillance in non‑traditional southern provinces, and targeted interventions along livestock trade routes to counter the clonal expansion of the dominant GT42 genotype.