New early warning system to predict dengue risk during soccer World Cup in Brazil

Researchers have developed an early warning system to predict the risk of dengue infections for the 553 microregions of Brazil during the football World Cup.

The estimates show that the chance of a dengue outbreak is enough of a possibility to warrant a high-alert warning in the three northeastern venues (Natal, Fortaleza, and Recife) but is likely to be generally low in all 12 host cities.

Lead author Dr Rachel Lowe from the Catalan Institute of Climate Sciences in Barcelona, Spain, said recent concerns about dengue fever in Brazil during the World Cup have made dramatic headlines, but these estimates have been based solely on averages of past dengue cases.

She said that the possibility of a large dengue fever outbreak during the World Cup, capable of infecting visitors and spreading dengue back to their country of origin, depends on a combination of many factors, including large numbers of mosquitoes, a susceptible population, and a high rate of mosquito-human contact.

In particular, climate has an important effect on dengue transmission in epidemic-prone areas where temperature and rainfall drive both mosquito and virus transmission dynamics. The risk of an epidemic increases shortly after a season of heavy rainfall, as occurred in the Amazon during the summer in Brazil.

Dr Lowe said their aim was to take the available evidence on real-time seasonal rainfall and temperature forecasts, transmission dynamics, and social and environmental variables (e.g., urbanisation), and combine it with the latest in mapping and mathematical modelling to produce robust risk estimates for the 12 host cities where matches will be played.

The researchers estimate little risk of dengue outbreaks during the forthcoming World Cup period in the southern and central capitals of Brasilia, Cuiaba, Curitiba, Porto Alegre, and Sao Paulo. However, they predict that there is some chance of dengue risk exceeding medium levels in Rio de Janeiro, Belo Horizonte, Salvador and Manaus. The three cities with the highest risk are Natal, Fortaleza, and Recife, although the risk still remains relatively low.

The study has been published in The Lancet Infectious Diseases.