Arbovirus Outbreak Reveals Co-Infection of Dengue and Chikungunya Viruses at Zona da Mata Region in Minas Gerais, Brazil, During 2024.

OBJECTIVES

To characterise the recent circulation of dengue and chikungunya viruses in the Zona da Mata region of Minas Gerais, Brazil, during the major arbovirus epidemic of 2024, using publicly available RT-qPCR test results.

METHODS

We analysed data from DATASUS obtained by RT-qPCR tests for dengue, Zika and chikungunya viruses reported between January and September 2024 across 41 municipalities. Demographic and epidemiological patterns were assessed, including virus-specific incidence, re-infection, sequential infection and co-infection events, and associations with testing effort.

RESULTS

The investigation of DATASUS data showed that 5583 patients were tested by RT-qPCR, and 1663 dengue virus cases and 1756 chikungunya virus cases were detected, with most detections between March and April. Different co-infections were detected in 278 patients, and sequential and re-infections in two and five individuals, respectively. Most cases clustered temporally between March and April, coinciding with the rainy season. Dengue was more common among adolescents and young adults, while chikungunya predominated in individuals over 40. Higher detection rates were observed in females. No Zika virus cases were identified. The number of confirmed cases was strongly correlated with the number of samples tested but not with municipality population size, underscoring the limitations of passive surveillance.

CONCLUSIONS

Our findings highlight dengue and chikungunya viruses' intense transmission and co-circulation in a historically understudied region. The high frequency of co-infections, age-specific risks and testing-dependent incidence patterns reinforce the importance of expanding molecular diagnostic capacity and strengthening surveillance networks in the face of increasingly severe arbovirus epidemics.