Human Brucellosis in Southeast Iran (2019-2023): Descriptive Epidemiology and Temporal Trends Based on Surveillance...

Human brucellosis remains a persistent zoonotic and occupational health challenge in endemic regions of the Middle East. Despite long-standing national control efforts, limited region-specific evidence is available from southeastern Iran. This study described the demographic characteristics, exposure patterns, temporal and seasonal trends and spatial distribution of laboratory-confirmed human brucellosis in districts covered by the Iranshahr University of Medical Sciences between 2019 and 2023.

A retrospective descriptive study was conducted using routine surveillance records of all confirmed brucellosis cases. Demographic, occupational and exposure variables were summaried using descriptive statistics, and associations were assessed using Pearson's χ² test. Multivariable logistic regression was applied to identify factors associated with reported livestock contact. Annual and cumulative incidence rates per 100,000 population were calculated using official district census data, and spatial patterns were examined using GIS-based mapping.

A total of 758 confirmed cases were recorded, with a mean age of 34.7 years. Females (61.3%) and rural residents (86.4%) predominated. Housewives (43.4%) and livestock farmers (33.2%) represented the main occupational groups. Reported exposures included consumption of unpasteuried dairy products (87.2%) and direct animal contact (81.9%). Livestock farming (OR 3.01; 95% CI: 1.74-5.21) and unpasteuried dairy consumption (OR 1.86; 95% CI: 1.13-3.06) were independently associated with livestock contact. Incidence peaked during spring and summer, with an overall declining trend over the study period. Higher cumulative incidence was observed in Sarbaz, Iranshahr and Dalgan districts.

Human brucellosis remains endemic in southeastern Iran, disproportionately affecting rural populations engaged in traditional livestock practices. Strengthened One Health interventions including expanded livestock vaccination, community-based food safety education and integrated cross-sectoral surveillance are required to reduce transmission and disease burden.