Introduction
Brucellosis is a global zoonotic disease caused by Brucella species that affects humans and livestock. In China, human brucellosis has risen from a historically endemic pattern to a broader national spread by 2023. This article synthesizes spatiotemporal epidemiological characteristics of human brucellosis in Henan Province, covering 1956–2023, to illuminate long-term trends, geographic spread, and cluster dynamics that inform targeted interventions.
Data sources and methods
Data were drawn from China’s National Notifiable Infectious Disease Reporting Information System, spanning 1956–2023. Analyses included: (i) incidence and case counts; (ii) joinpoint regression to identify significant temporal shifts and trends; (iii) retrospective space-time scanning (Poisson model) to detect spatiotemporal clusters; and (iv) geographic visualization with ArcGIS. The study used standard epidemiological metrics such as annual percentage change (APC), average annual percentage change (AAPC), and relative risk (RR) for cluster evaluation.
Epidemiological evolution in Henan (1956–2023)
Across the study period, Henan experienced two major epidemic phases: an initial wave (1956–1980) with an average annual incidence of 1.46/100,000 and a peak in 1969; followed by a low period (1981–1999) and a re-emergent phase from 2000 onward, with rising incidence due to livestock industry growth. From 2004 to 2023, the province recorded 50,404 cases, with a shifting pattern from imported/sporadic cases to sustained local transmission after 2011. The long-term trend shows a continuous rise in incidence, with the 2004–2023 period reflecting an uptick in geographic spread and a rising average incidence rate (approx. 1.3/100,000 overall across 1956–2023). The study also notes high annual growth rates in certain years and regions, underscoring heterogeneity across time and space.
Geographic burden at city and county levels (2004–2023)
From 2004 to 2023, 50,404 brucellosis cases were reported across 18 cities, with Pingdingshan and Nanyang bearing the highest caseloads. The average annual growth rate in Henan was 17.04%, with city-level growth rates ranging from 3.25% to 43.23%. At the county level, cases increased from 39 in 2004 to 155 in 2023, expanding from northwest high-incidence pockets toward central and eastern areas. This spatial shift indicates an eastward expansion of risk within Henan, consistent with broader patterns observed in northern China where brucellosis gradually moves from pastureland toward agricultural and peri-urban zones.
Spatiotemporal clustering patterns
Retrospective space-time scanning identified two significant clusters (2004–2023). A high–high cluster covered 31 counties predominantly in western Henan (Nanyang, Luoyang, Pingdingshan, Sanmenxia, Zhumadian) with RR 5.37 (P < 0.001) and a primary time window from 2014 to 2023. A low–low cluster encompassed 81 eastern counties (Shangqiu, Kaifeng, Zhoukou, Xinxiang, Puyang, Xuchang, Xinyang, etc.) with RR 0.24 (P < 0.001) ranging from 2010 to 2019. The results reveal a central west–east gradient in transmission risk and highlight expanding vulnerabilities into eastern Henan, signaling the need for cross-regional coordination and harmonized control measures across counties and cities.
Temporal dynamics and trends
Joinpoint analyses show a complex temporal pattern with an early rapid rise (1956–1967, APC ≈ 46%), a mid-era decline (1967–1988, APC ≈ −25%), and a strong renewed rise (1988–2023, APC ≈ 24%). The overall trend (1956–2023) remained significantly upward (AAPC ≈ 9%). City-level analyses indicated multiple joinpoints across Zhengzhou, Luoyang, Xinxiang, Jiaozuo, Nanyang, Xinyang, Zhoukou, and others, reflecting local variations in growth rates and public health responses. These findings suggest re-emergence aligned with livestock industry expansion and animal movement patterns within and beyond Henan.
Public health implications
The persistent growth and geographic spread of brucellosis in Henan call for reinforced animal health strategies, including restricted movement of infected animals, enhanced vaccination programs for ruminants, and improved market sanitation. Cross-provincial collaboration with Shaanxi, Shanxi, Anhui, and Hubei is crucial given regional spillovers and neighboring endemic zones. Human-centered measures—education on safe animal product handling, workplace PPE, and robust surveillance—will be essential to curb transmission from animals to people.
Limitations and future directions
The analysis relies on NNDRS data, which may underestimate true incidence due to underreporting and evolving diagnostic criteria over the decades. Future work should integrate standardized prospective data collection, molecular characterization of Brucella strains, and one-health approaches that link animal and human brucellosis surveillance to clarify transmission networks and to tailor region-specific interventions.
Conclusion
From 1956 to 2023, Henan Province experienced a clear escalation and geographic expansion of human brucellosis, marked by western high-risk clusters and eastern spread. The spatiotemporal patterns underscore the need for comprehensive, coordinated control strategies spanning animal vaccination, movement controls, market hygiene, and public health education to reduce the brucellosis burden in Henan and its neighboring regions.
