BackgroundChikungunya virus (CHIKV) is anAedesmosquito-borne
virus that has caused large epidemics linked to acute, chronic, and severe
clinical outcomes. Currently, Brazil has the highest number of chikungunya
cases in the Americas. We aimed to investigate the spatiotemporal dynamics
and recurrence pattern of chikungunya in Brazil since its introduction in
2013.MethodsIn this epidemiological study, we used CHIKV genomic sequencing data,
CHIKV vector information, and aggregate clinical data on chikungunya cases
from Brazil. The genomic data comprised 241 Brazilian CHIKV genome sequences
from GenBank (n=180) and the 2022 CHIKV outbreak in Ceará state
(n=61). The vector data (Breteau index and House index) were obtained from
the Brazilian Ministry of Health for all 184 municipalities in Ceará
state and 116 municipalities in Tocantins state in 2022. Epidemiological
data on laboratory-confirmed cases of chikungunya between 2013 and 2022 were
obtained from the Brazilian Ministry of Health and Laboratory of Public
Health of Ceará. We assessed the spatiotemporal dynamics of
chikungunya in Brazil via time series, mapping, age–sex distribution,
cumulative case-fatality, linear correlation, logistic regression, and
phylogenetic analyses.FindingsBetween March 3, 2013, and June 4, 2022, 253 545 laboratory-confirmed
chikungunya cases were reported in 3316 (59·5%) of 5570
municipalities, mainly distributed in seven epidemic waves from 2016 to
2022. To date, Ceará in the northeast has been the most affected
state, with 77 418 cases during the two largest epidemic waves in 2016 and
2017 and the third wave in 2022. From 2016 to 2022 in Ceará, the odds
of being CHIKV-positive were higher in females than in males (odds ratio
0·87, 95% CI 0·85–0·89, p<0·0001),
and the cumulative case-fatality ratio was 1·3 deaths per 1000 cases.
Chikungunya recurrences in the states of Ceará, Tocantins (recurrence
in 2022), and Pernambuco (recurrence in 2021) were limited to municipalities
with few or no previously reported cases in the previous epidemic waves. The
recurrence of chikungunya in Ceará in 2022 was associated with a new
East-Central-South-African lineage. Population density metrics of the main
CHIKV vector in Brazil,Aedes aegypti, were not correlated
spatially with locations of chikungunya recurrence in Ceará and
Tocantins.InterpretationSpatial heterogeneity of CHIKV spread and population immunity might
explain the recurrence pattern of chikungunya in Brazil. These results can
be used to inform public health interventions to prevent future chikungunya
epidemic waves in urban settings.FundingGlobal Virus Network, Burroughs Wellcome Fund, Wellcome Trust, US
National Institutes of Health, São Paulo Research Foundation, Brazil
Ministry of Education, UK Medical Research Council, Brazilian National
Council for Scientific and Technological Development, and UK Royal
Society.