The dengue virus (DENV) is an arbovirus belonging to the Flaviviridae family; the species comprises four antigenically distinct serotypes (DENV–1, DENV–2, DENV–3, and DENV–4), which are further subdivided into genotypes. The virus is transmitted to humans through mosquito bites, primarily from the Aedes spp. genus. Dengue is endemic in various parts of the world, including tropical and subtropical regions of Asia, Latin America, Africa, and Oceania. In Brazil, the state of Tocantins, located in north-central Brazil, has experienced a significant number of arboviral disease cases, particularly dengue. This study aimed to monitor DENV circulation within the state by conducting full genome sequencing of viral genomes recovered from 61 patients between June 2021 and July 2022. During this period, both DENV-1 and DENV-2 serotypes were identified. Our findings confirm the circulation of DENV serotypes 1 and 2 in Tocantins, affecting males and females equally, with younger age groups (4 to 43 years old) being the most susceptible. Phylogenetic analysis revealed that the circulating viruses belong to DENV–1 genotype V American and DENV–2 genotype III Southeast Asian/American. The Bayesian analysis of DENV-1 Genotype V sequenced here is closely related to genomes previously sequenced in the state of São Paulo. Regarding DENV-2 genotype III genomes, these are clustered in a distinct, well-supported subclade, along with previously reported isolates from the states of Goiás and São Paulo. In both cases, our results suggest that multiple introductions of these genotypes occurred in the Tocantins state. This observation highlights the significant impact of major population centers in Brazil on virus dispersion, including other Latin-American countries and the USA. In the SNP analysis, DENV-1 displayed 122 distinct missense mutations, while DENV-2 had 44, with significant mutations predominantly occurring in the envelope and NS5 proteins. The analyses performed here reveal the concomitant circulation of distinct DENV-1 and -2 genotypes in some Brazilian states, underscoring the dynamic evolution of the DENV and the ongoing significance of surveillance efforts in supporting public health policies.

The Chikungunya virus (CHIKV) presents global health challenges, with Brazil witnessing out-breaks since its introduction in 2014. In 2023, Minas Gerais (MG) experienced a CHIKV outbreak, prompting entomological investigations to identify vectors, viral lineages, and assess insecticide resistance. This study utilized social media platforms and citizen science concept to conduct a comprehensive entomological survey. Following Instagram posts, residents with CHIKV sus-pected cases were able to schedule mosquito aspirations. During the aspirations, 421 mosquitoes (165 Aedes aegypti and 256 Culex quinquefasciatus) were captured from 40 households in Salinas city (MG) and tested for Dengue, Zika and Chikungunya viruses through RT-qPCR. Twelve out 57 pools (10 of Ae. aegypti and 2 of Cx. quinquefasciatus) tested positive for CHIKV RNA. Viral RNA was also detected in the heads of 9 Ae. aegypti individuals (but not in Cx. quinquefasciatus). Genome sequencing revealed that CHIKV belonged to the East-Central-South-Africa (ECSA) genotype. Additionally, genetic analyses revealed high frequencies of kdr alleles, suggesting resistant to pyrethroids insecticides in this Ae. aegypti population. These findings emphasize the urgent need for innovative vector study and control strategies to combat arbovirus transmission, and inter-disciplinary approaches in public health interventions.