Emergence of Dengue Virus Serotype 2 Cosmopolitan Genotype in Costa Rica.

Dengue virus produces dengue fever, which can cause severe manifestations. Virus serotype and genotype may impact the epidemiology and severity of the disease. At the Hospital México (Costa Rica), dengue diagnosis and serotyping are performed with molecular tests, but selected samples are sequenced using Illumina technology. In May 2024, we analyzed two dengue-positive samples through genomic sequencing and detected dengue serotype 2, Cosmopolitan genotype. Phylogenetic comparisons revealed that the Costa Rican genomes are closely related to those from Brazil, Peru, and Colombia. Molecular dating estimated that the sequences from Costa Rica diverged in January 2024, suggesting that this genotype may already have been circulating in the country. The emergence of this genotype could impact the severity and epidemiology of dengue in Costa Rica. Therefore, genomic and epidemiological surveillance of dengue cases locally is important to better understand the public health impact of this new genotype in the country.