Chikungunya virus dynamics and persistence in body fluids—Nanning, Guangxi Province, China, 2025

Abstract

In 2025, China experienced its largest outbreak of Chikungunya virus (CHIKV), an acute infectious disease transmitted by Aedes mosquitoes. This study aims to analyze the dynamic changes, developmental trends, and persistence of CHIKV in body fluids, based on infection data collected from Nanning, China. A total of 506 specimens were longitudinally obtained from 53 hospitalized patients in Nanning, China. Positivity rates among different specimen types were compared using the Chi-square test or Fisher’s exact test, while the Kruskal-Wallis test was applied to evaluate differences in cycle threshold (Ct) values. To estimate the probability of viral detection, generalized estimating equations (GEE) were employed, and parametric survival analysis was conducted to examine the duration of viral persistence in human body fluids. Serum had the highest positivity rate (81.20%), followed by plasma (72.50%), while urine (4.73%) and saliva (11.03%) were much lower. In the first four days following the onset of symptoms, the median Ct values for serum and plasma were lower compared to those for saliva and urine. According to GEE analysis, saliva showed the quickest decline in the likelihood of a positive test result, decreasing from 52.2% on day 1 to just 0.7% by day 7. Serum and plasma followed, with positivity rates dropping from over 85% on day 3 to around 30% by day 7. Urine consistently had low positivity rates and did not show a statistically significant relationship with the number of days since symptoms began. Parametric survival analysis indicated similar median durations of serum (5.8 days, 95% CI : 4.8–6.9) and plasma (5.8 days, 95% CI : 4.7–7.1), while saliva had a shorter median duration of 3.5 days (95% CI : 3.0–4.1). Urine was not included in this analysis due to an insufficient number of positive samples. Blood is the preferred sample for detecting the chikungunya virus and accurately assessing the duration of the virus in the body; additionally, compared to urine, saliva is more sensitive for detecting the virus during the acute phase of the disease, which is important for subsequent transmission and public health control measures.