Clinical and molecular analysis of a Chikungunya Virus outbreak in Southern Spain

Chikungunya Virus (CHIKV), primarily endemic to parts of Africa and Europe, has recently emerged as a public health concern in new geographic regions. This study reports the cases detected in Andalusia, southern Spain, during 2023. A multidisciplinary approach was employed, combining epidemiological investigations, virological diagnostic methods and viral genome sequencing and bioinformatic analysis to confirm the cases and identify transmission dynamics. During 2023, 32 probable or confirmed imported human cases of CHIKV infection were investigated in Andalusia. More than 90% of the cases were visiting friends and relatives and immigrants from Paraguay. Female gender, a subacute or chronic infection and arthritis and skin rash were the most frequent clinical-epidemiological characteristics. Serological and/or molecular testing confirmed CHIKV as the causative agent. Phylogenetic analysis of the viral genomes corresponding to four, out of the nine confirmed cases, suggested close relatedness to strains currently circulating in Brazil and Uruguay. This study highlights the geographic expansion of CHIKV and underscores the need for enhanced surveillance and vector control strategies in Spain. Public health interventions should focus on preventing further human especially in areas where imported cases are detected, based on a one health approach that includes vector control and mosquito populations monitoring.