Objective:To analyze the clinical characteristics of the Chikungunya fever outbreak in Shunde District, Foshan City, Guangdong Province in July 2025 and the risk factors associated with delayed viral RNA clearance.Methods:A total of 562 patients with Chikungunya fever admitted to three designated hospitals in Shunde District from July 10 to 30, 2025 were enrolled. Demographic data, clinical manifestations, and laboratory findings were collected. Patients were categorized into four age groups including minors (<18 years), young adults (18 to 39 years), middle-aged adults (40 to 64 years) and elderly adults (≥65 years). The differences of clinical characteristics among these age groups were analyzed. Intergroup comparisons were performed using chi-square test, one-way analysis of variance, or Kruskal-Wallis H test. Pairwise comparisons between groups were conducted using the Bonferroni or Games-Howell or Dunn method. Binary logistic regression was employed to analyze risk factors associated with delayed viral RNA clearance (>7 days). Results:The mean age of the 562 enrolled Chikungunya fever patients was (44.8±21.3) years. Fever, arthralgia and rash were the three core symptoms, with incidence rates of 87.5% (492/562), 88.4%(497/562) and 69.6%(391/562), respectively. At discharge, only 54.1%(304/562) of patients achieved complete symptom resolution, while 26.5%(149/562) still had arthralgia and 36.1%(203/562) had residual rash. Significant differences were observed among age groups in the incidence of fever ( χ2=9.43, P=0.024), peak body temperature ( F=6.54, P<0.001), incidence of arthralgia ( χ2=26.89, P<0.001), duration of arthralgia ( F=12.68, P=0.001), incidence of rash ( χ2=68.99, P<0.001), rate of residual rash at discharge ( χ2=32.37, P<0.001), lymphocyte count ( F=12.94, P<0.001), platelet count ( F=14.95, P<0.001), and C-reactive protein levels (CRP) ( H=94.18, P<0.001). Further pairwise comparisons revealed that compared to the middle-aged and elderly groups, the minor group had a higher incidence of fever and a lower incidence of arthralgia, and the duration of arthralgia was shorter than the elderly group (all P<0.008 3). Compared with the other three groups, the elderly group had lower incidence and residual rate of rash, and lower platelet counts (all P<0.008 3), and higher levels of CRP (all P<0.05). The elderly group had lower lymphocyte counts compared to the minor and young adult groups (both P<0.05). Significant differences were found among age groups in the time to viral RNA clearance ( F=5.77, P=0.003) and length of hospital stay ( F=11.64, P<0.001), with the elderly group having significantly longer duration for both compared to the other three groups (all P<0.05). Multivariate analysis showed that advanced age (odds ratio ( OR)=1.049, 95% confidence interval ( CI) 1.015 to 1.083), longer duration of fever ( OR=1.529, 95% CI 1.086 to 2.155) and longer duration of arthralgia ( OR=1.927, 95% CI 1.318 to 2.817) were independent risk factors for delayed viral RNA clearance (all P<0.05). Conclusions:Patients with Chikungunya fever in Shunde District primarily present with fever, arthralgia and rash. The incidence and characteristics of these three core symptoms show age-related variations. Elderly patients and those with longer durations of fever or arthralgia are more likely to experience delayed viral clearance.

Objective:To analyze the clinical characteristics of the Chikungunya fever outbreak in Shunde District, Foshan City, Guangdong Province in July 2025 and the risk factors associated with delayed viral RNA clearance.Methods:A total of 562 patients with Chikungunya fever admitted to three designated hospitals in Shunde District from July 10 to 30, 2025 were enrolled. Demographic data, clinical manifestations, and laboratory findings were collected. Patients were categorized into four age groups including minors (<18 years), young adults (18 to 39 years), middle-aged adults (40 to 64 years) and elderly adults (≥65 years). The differences of clinical characteristics among these age groups were analyzed. Intergroup comparisons were performed using chi-square test, one-way analysis of variance, or Kruskal-Wallis H test. Pairwise comparisons between groups were conducted using the Bonferroni or Games-Howell or Dunn method. Binary logistic regression was employed to analyze risk factors associated with delayed viral RNA clearance (>7 days). Results:The mean age of the 562 enrolled Chikungunya fever patients was (44.8±21.3) years. Fever, arthralgia and rash were the three core symptoms, with incidence rates of 87.5% (492/562), 88.4%(497/562) and 69.6%(391/562), respectively. At discharge, only 54.1%(304/562) of patients achieved complete symptom resolution, while 26.5%(149/562) still had arthralgia and 36.1%(203/562) had residual rash. Significant differences were observed among age groups in the incidence of fever ( χ2=9.43, P=0.024), peak body temperature ( F=6.54, P<0.001), incidence of arthralgia ( χ2=26.89, P<0.001), duration of arthralgia ( F=12.68, P=0.001), incidence of rash ( χ2=68.99, P<0.001), rate of residual rash at discharge ( χ2=32.37, P<0.001), lymphocyte count ( F=12.94, P<0.001), platelet count ( F=14.95, P<0.001), and C-reactive protein levels (CRP) ( H=94.18, P<0.001). Further pairwise comparisons revealed that compared to the middle-aged and elderly groups, the minor group had a higher incidence of fever and a lower incidence of arthralgia, and the duration of arthralgia was shorter than the elderly group (all P<0.008 3). Compared with the other three groups, the elderly group had lower incidence and residual rate of rash, and lower platelet counts (all P<0.008 3), and higher levels of CRP (all P<0.05). The elderly group had lower lymphocyte counts compared to the minor and young adult groups (both P<0.05). Significant differences were found among age groups in the time to viral RNA clearance ( F=5.77, P=0.003) and length of hospital stay ( F=11.64, P<0.001), with the elderly group having significantly longer duration for both compared to the other three groups (all P<0.05). Multivariate analysis showed that advanced age (odds ratio ( OR)=1.049, 95% confidence interval ( CI) 1.015 to 1.083), longer duration of fever ( OR=1.529, 95% CI 1.086 to 2.155) and longer duration of arthralgia ( OR=1.927, 95% CI 1.318 to 2.817) were independent risk factors for delayed viral RNA clearance (all P<0.05). Conclusions:Patients with Chikungunya fever in Shunde District primarily present with fever, arthralgia and rash. The incidence and characteristics of these three core symptoms show age-related variations. Elderly patients and those with longer durations of fever or arthralgia are more likely to experience delayed viral clearance.