Analysis of the Epidemiological Characteristics and Risk Factors for Severe Progression of Scrub Typhus in the Dali Region of China

BACKGROUND We analyzed the epidemiological traits and risk factors of severe scrub typhus cases in Dali, China, to form a theoretical basis for local prevention and control. MATERIAL AND METHODS We analyzed the epidemiological characteristics of patients with scrub typhus admitted to our hospital from January 1, 2015, to December 31, 2024. Based on the severity of scrub typhus, the patients were divided into a severe scrub typhus group (n=89) and mild scrub typhus group (n=370). Logistic regression analysis was used to identify the risk factors for severe scrub typhus. RESULTS This study included 459 patients with scrub typhus in the Dali region (191 males and 268 females), with the peak incidence concentrated from July to October. Multivariate logistic regression analysis demonstrated that a blood urea nitrogen level over 7.3 mmol/L (P=0.040, OR=1.12), platelet count of 71×10⁹/L or lower (P=0.036, OR=0.98), and concurrent liver injury (P=0.033, OR=2.70) were risk factors for the progression to severe scrub typhus. When these 3 factors were combined, the area under the receiver operating characteristic curve reached a maximum value of 0.81 (95% CI: 0.75-0.86). CONCLUSIONS Scrub typhus in the Dali region occurs predominantly from July to October, with a higher prevalence among female patients in rural areas. Patients with blood urea nitrogen level over 7.3 mmol/L, platelet count of 71×10⁹/L or lower, and concurrent liver injury are at an increased risk of progressing to a severe condition.