Chikungunya virus in Europe: A retrospective epidemiology study from 2007 to 2023

Background Chikungunya virus (CHIKV), a mosquito-borne alphavirus, is responsible for disease outbreaks worldwide. However, systematic knowledge of spatiotemporal distribution and risk patterns of CHIKV in mainland Europe remains unclear. Our aim was to decipher the epidemiological characteristics, diversity, and clinical manifestations of CHIKV.Methods In this retrospective study, we retrieved the surveillance bulletins of chikungunya infections reported in Europe during 2007-2023 to depict the epidemiological characteristics. We performed genotyping and phylogenetic analyses to examine the evolution and mutation. We also searched PubMed, Web of Science, and Google Scholar to conduct meta-analyses of clinical manifestations.Results 4730 chikungunya cases across twenty-two countries were documented in mainland Europe from 2007-2022, with no cases reported in 2023. The age-standardized incidence rate was highest in 2014 (0.31), with significant variations observed in each country per year. Although autochthonous outbreaks occurred in several countries, the majority of cases were travel-related, with individuals mainly getting infected during summer vacation. Most travel-related cases were reported as being acquired in India (11.7%), followed by Dominican Republic (9.0%), Guadeloupe (8.7%), and Thailand (7.8%). Genotyping of genome sequences identified two genotypes, with the majority belonging to II-ECSA. The E1 A226V mutation was detected from autochthonous outbreaks, including Italy in 2007 and France in 2014 and 2017. The most common symptoms reported were fever (97.6%), joint pain (94.3%), fatigue (63.5%), and skin rash (52.3%).Conclusion The suitable niches for CHIKV are expanding due to climate change and global travel. With the absence of specific antiviral treatments and vaccines still in development, surveillance and vector control are essential in suppressing the re-emergence and epidemics of CHIKV.