IC3 scientists and partners 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, published in The Lancet Infectious Diseases, show that the chance of a dengue outbreak is likely to be generally low in all twelve host cities. However, there is enough of a possibility to warrant a high-alert warning in the three northeastern venues (Natal, Fortaleza, and Recife).
Dengue is a viral infection that is transmitted between humans by Aedes aegypti mosquitoes. In some cases, it causes life-threatening illness. There are currently no licensed vaccines or treatments against dengue. So far this century, Brazil has recorded more cases of dengue fever than anywhere else in the world, with more than 7 million cases reported between 2000 and 2013.
The research team developed a spatio-temporal statistical model to make dengue predictions for the 553 microregions of Brazil, based on multiple risk factors, including seasonal climate forecasts. They then used dengue severity thresholds, that are used by the Ministry of Health, to work out the chance of dengue cases exceeding medium and high levels.
By assessing the performance of the early warning system on past data, they devised optimum trigger thresholds to indicate whether low, medium or high warnings should be issued for the 12 host venues.
"Our model showed that the risk of dengue outbreaks for all twelve host venues was more likely to be low. However, in the northeastern cities of Natal and Fortaleza, followed by Recife, there was a greater chance of exceeding the high level threshold of 300 cases per 100,000 inhabitants. Therefore, these cities deserve more attention in terms of vector control. "
An effective early warning system for dengue that takes into account multiple factors, including real-time climate forecasts, allows the concentration of vector control efforts to those areas most at risk, three months in advance. This may be useful, not only ahead of major global events, but also before the peak dengue season each year, to control or contain potentially explosive dengue epidemics.
The research was conducted by an international, multidisciplinary team of climate scientists, public health specialists and mathematical modellers from Spain (Catalan Institute of Climate Sciences - IC3), the UK (Met Office, University of Exeter) and Brazil (Center for Weather Forecasting and Climate Research – CPTEC/INPE, Fiocruz, Ministry of Health, University of Brasilia).
Title: Dengue outlook for the World Cup in Brazil: an early warning model framework driven by real-time seasonal climate forecasts
Authors: Rachel Lowe, Christovam Barcellos, Caio A S Coelho, Trevor C Bailey, Giovanini Evelim Coelho, Richard Graham, Tim Jupp, Walter Massa Ramalho, Marilia Sá Carvalho, David B Stephenson and Xavier Rodó
Publisher: The Lancet Infectious Diseases Year: 2014