Spatial-temporal dynamics and recurrence of chikungunya virus in Brazil

Chikungunya virus (CHIKV) is an Aedes mosquito-borne virus that has caused explosive epidemics linked to acute, chronic, and severe clinical outcomes. Since 2014, Brazil has had the highest number of chikungunya fever (CHIKF) cases in the Americas. Here, we report and contextualize the spatiotemporal dynamic of CHIKF in Brazil and combine genomic, epidemiological, and vector analyses to investigate CHIKF recurrence in several Brazilian states. From 2013 to 2022, CHIKV caused seven epidemic waves across Brazil, affecting 59.5% (3,316 of 5,570) of the countrys municipalities. To date, Ceara State in the northeast has been the most affected, with 81,274 cases during the two largest epidemic waves in 2016 and 2017, and the ongoing third wave in 2022. The 2022 CHIKF recurrence was associated with a new introduction of an East/Central/South African strain. Also, the CHIKV recurrences in Ceara, Tocantins, and Pernambuco States were limited to municipalities with few or no prior reported cases in the previous epidemic waves, suggesting that spatial heterogeneity of CHIKV spread and population immunity may explain the recurrence pattern in the country. In addition, the population density metrics of main CHIKV vector in Brazil, Ae. aegypti, were not correlated spatially with locations of CHIKF recurrence in Ceara and Tocantins States. Also, we show that CHIKF disproportionally affected females, and we estimated the case-fatality ratio in Ceara at [~]1.3 deaths per 1,000 cases. These findings more comprehensively describe CHIKV epidemics in Brazil and contribute to understanding CHIKF recurrence in urban settings. Overall, this information may help guide public health policy to mitigate and reduce the burden of urban arboviruses.