Early warning system predicts dengue fever risk during the Brazil World Cup

University of Exeter scientists have helped develop an early-warning system to predict the risk of dengue fever outbreaks in Brazil during the forthcoming World Cup.

The study, developed by a team of European scientists, estimates the chances of outbreaks of the mosquito-borne infection disease in Brazil’s administrative areas – or microregions – during this summer’s festival of football.

The study, published in leading medical journal The Lancet Infectious Diseases, shows that there is a high enough risk to warrant a ‘high-alert’ warning  for the three north-eastern venues of Natal, Fortaleza and Recife – the latter of which will host England in their second round match if they top their opening group.

Dengue is a viral infection that is transmitted between humans by mosquitoes, and can cause life-threatening illnesses in some cases. There are currently no licensed vaccines or treatments available.

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 scientists, who include Professor David Stephenson, Professor Trevor Bailey and Dr Tim Jupp from Exeter’s College of Engineering, Mathematics and Physical Sciences, looked at rain and temperature data over a 30-year period, as well as population density and altitude data.

Professor David Stephenson, from Exeter’s Mathematics department said: “Similar to many infectious diseases, the risk of dengue dynamically depends on local climate and so varies in time and space. Our study uses a state-of-the-art statistical model to combine operational climate forecasts with socioeconomic factors to make probabilistic warnings of dengue.”

The researchers estimate that the risk of dengue fever outbreaks in the southern and central capitals of Brasília, Cuiabá, Curitiba, Porto Alegre, and São Paulo are low.

They also predict 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.

Dr Rachel Lowe from the Catalan Institute of Climate Sciences in Barcelona, Spain and lead author of the study 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.

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.

“The ability to provide early warnings of dengue epidemics at the microregion level, three months in advance, is invaluable for reducing or containing an epidemic and will give local authorities the time to combat mosquito populations in those cities with a greater chance of dengue outbreaks.”

The research was conducted by an international, multidisciplinary team of climate scientists, public health specialists and mathematical modellers from Spain, the UK and Brazil.

*Source: University of Exeter

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