# Diagnostic and genomic characterization of an imported chikungunya virus case in Ningxia Hui Autonomous Region, China, September 2025

## TL;DR

This paper reports the first imported case of chikungunya virus in Ningxia, China, and highlights the risk of local transmission due to a key mutation in the virus.

## Contribution

The study documents the first imported chikungunya case in Ningxia and identifies a mutation linked to increased transmission risk.

## Key findings

- The imported chikungunya case in Ningxia was linked to the ECSA Indian Ocean Lineage (ECSA2).
- The E1-A226V mutation was detected, which enhances transmission by Aedes albopictus mosquitoes.
- The strain showed 99.21% nucleotide identity with a 2025 Foshan outbreak isolate.

## Abstract

•First imported chikungunya case documented in Ningxia, China, September 2025.•Patient had recent travel history to Shandong Province before symptom onset.•Whole-genome sequencing identified ECSA Indian Ocean Lineage (ECSA2).•Key E1-A226V mutation enhancing Ae. albopictus transmission detected.•Strain shared 99.21% nucleotide identity with 2025 Foshan outbreak isolate.

First imported chikungunya case documented in Ningxia, China, September 2025.

Patient had recent travel history to Shandong Province before symptom onset.

Whole-genome sequencing identified ECSA Indian Ocean Lineage (ECSA2).

Key E1-A226V mutation enhancing Ae. albopictus transmission detected.

Strain shared 99.21% nucleotide identity with 2025 Foshan outbreak isolate.

To analyze the first imported case of chikungunya virus (CHIKV) in Ningxia Hui Autonomous Region (Ningxia), China, and to provide insights for the prevention and control of emerging infectious diseases. An epidemiological investigation and viral detection was performed via quantitative reverse transcription polymerase chain reaction (qRT-PCR). The virus was further characterized using whole-genome sequencing and phylogenetic analysis. A 26-year-old female was confirmed to be infected with CHIKV. Genotypic analysis identified the East/Central/South African (ECSA) Indian Ocean Lineage (IOL), specifically the ECSA2 sub-lineage. A key mutation (E1-A226V), known to enhance viral adaptability to Aedes albopictus, was identified. Phylogenetic analysis revealed 99.21% nucleotide similarity to a CHIKV strain isolated in Foshan City, Guangdong Province, in 2025. No Ae. aegypti or Ae. albopictus were found in Ningxia. This imported case of CHIKV in Ningxia, genetically linked to the ECSA-IOL lineage carrying the E1-A226V mutation, underscores the risk of introduction and potential local transmission of arboviruses via domestic travel. Enhanced surveillance, timely diagnosis, and effective management of imported cases are essential for preventing outbreaks.

Image, graphical abstract