Epidemiology of human brucellosis in Nahavand county, Hamadan Province, western Iran: an 8-year (2010–2017) registry-based analysis

BACKGROUND: Brucellosis is an infectious zoonosis, which greatly afflicts human health and animal productivity. OBJECTIVES: To describe the trends and epidemiological characteristics of human brucellosis in Nahavand county, Hamadan Province, western Iran over 8 years (2010–2017). METHODS: In this registry-based longitudinal study, we analyzed all reported cases of human brucellosis, including 1,130 patients from 2010 to 2017. A checklist including demographic and clinical characteristics of patients with reported cases of brucellosis had been used to gather data. We calculated annual percent changes (APCs) and average annual percent changes (AAPCs) using Joinpoint software to determine the trend of brucellosis using a segmented regression model. RESULTS: Among the patients, 60.9% were male and 87.3% lived in rural areas. The mean age of the patients was 35.9 ± 18.34 years. Compared with male patients, female patients were more affected when they were elderly (15.6% men vs. 24.2% women for those aged ≥55 years) (P = 0.001). Of patients with brucellosis, 65.2% had consumed unpasteurized dairy products and 82.3% had a history of contact with animals. The incidence of human brucellosis in Nahavand county increased between 2010 and 2014, then decreased in 2015, and thereafter remained steady. Per 100,000 population, the AAPC pertaining to the incidence was 17.4 in the male population (95% CI: 4.4, 31.9), 13.8 in the female population (95% CI: 0.2, 29.3), and 16.1 in rural dwellers (95% CI: 2.2, 31.8) indicating an increasing trend from 2010 to 2017 (P < 0.05). CONCLUSION: The incidence of brucellosis in the western part of Iran is high and remains a challenging health problem. In the present study, age, job, sex, and seasonal changes are important risk factors for human brucellosis.