Long-Term Epidemiological Insights Into Human Cystic Echinococcosis in Northeastern Iran: A 17-Year Retrospective Analysis.

Background: Cystic echinococcosis (CE) remains an important public health challenge in endemic regions of Iran, especially in areas with intensive livestock farming and close human-animal contact. Long-term epidemiological analyses are essential for identifying patterns, informing control strategies, and evaluating intervention outcomes. Methods: A 17-year cross-sectional study design based on retrospective data (2006-2022) was conducted on surgically confirmed human CE cases from two referral hospitals in Razavi Khorasan Province, northeastern Iran. Demographic, clinical, and spatial data from patients residing in Torbat-e Heydariyeh, Zaveh, Mahvelat, and Roshtkhar were reviewed. Descriptive and inferential statistical analyses were performed using SPSS v.25, including chi-square, Mann-Whitney U, and one-way ANOVA tests (α = 0.05). Temporal trends were assessed using Poisson regression, and case distribution was visualized via GIS-based heatmapping (ArcGIS Pro 3.2). Results: A total of 232 CE surgical cases were recorded during a 17-year period, corresponding to an average annual incidence of 13.6 and a surgical incidence rate of 3/100,000 population. The liver was the most affected organ (81.5%), and abdominal pain was the most frequent presenting symptom (73.7%). Two age peaks were observed at 21-40 and ≥ 61 years. Females (57.8%) and urban residents (64.7%) comprised the majority of patients. Regression analysis indicated a nonsignificant declining trend over time (β = -0.95, 95% CI: -2.71-0.81, p = 0.26). A statistically significant association was found between residency and organ involvement in patients with CE (χ 2 = 5.78, df = 1, p = 0.016). Conclusion: This 17-year analysis reveals persistent CE burden in northeastern Iran despite a modest decline in recent years. Sustained One Health surveillance, public education, and strengthened veterinary-human collaboration are required to mitigate disease transmission and improve control outcomes.