Viral Load Dynamics of Chikungunya Virus in Human Specimens - Foshan City, Guangdong Province, China, 2025.

What is already known about this topic?: Chikungunya virus (CHIKV) represents an Aedes-borne alphavirus that causes fever, rash, and severe arthralgia. Outbreaks have expanded across 119 countries, with sporadic imported cases documented in China. While serum has been regarded as the optimal diagnostic specimen, comprehensive data comparing multiple specimen types across all infection phases have remained lacking. What is added by this report?: Using 1,156 samples from the 2025 Foshan outbreak, we quantified CHIKV RNA levels from 6 days before to 12 days after symptom onset. Serum consistently yielded the highest viral loads, while saliva, urine, and throat swabs demonstrated inferior performance. Viral RNA detection was achievable as early as 1 day before symptom onset. Days 0-7 post-symptom onset constitute the phase of explosive viral replication, representing the optimal timeframe for specimen collection to minimize false-negative results. From Day 8 onward, antibody IgG testing should be incorporated to prevent diagnostic gaps. What are the implications for public health practice?: Pre-symptomatic polymerase chain reaction (PCR) testing of serum (day-1) enables interception of imported cases at ports of entry; days 0-7 represent the optimal clinical sampling window to minimize false negatives. After day 8, antibody testing must supplement molecular diagnostics. This systematic analysis of CHIKV viral-load kinetics provides critical evidence for calibrating quarantine duration, optimizing contact-tracing intensity, and allocating resources effectively, thereby reducing community transmission risk substantially.