England fans visiting Brazil for the World Cup next year have been warned of the risk of dengue fever by a health expert.
The disease, spread by mosquito bites, could be a problem in three of the 12 host cities next summer, Professor Simon Hay of Oxford University told the BBC.
He said there are no vaccines or drugs to prevent the disease but the best precaution is to avoid mosquito bites.
Fortaleza, Natal and Salvador are three of the host cities where dengue will be close to its peak.
Writing for Nature, Professor Hay says: "Like the weather, it is impossible to forecast the precise situation with regard to dengue in Brazil in 2014. We can, however, make informed guesses on the basis of averaged records of dengue in previous years.
"For the areas around nine of the World Cup stadiums, these records show that the main dengue season will have passed before the World Cup is held in June and July. Unfortunately, the risk remains high during these months in the northeast."
He advises: "Select accommodation with screened windows and doors and air conditioning; use insecticides indoors; wear clothing that covers the arms and legs, especially during early morning and late afternoon, when the chance of being bitten is greatest; and apply insect repellent to clothing and exposed skin.
Dengue is a tropical disease that can produce flu-like illness and hospitalise victims. Symptoms include fever, headache and muscle pains. In some cases the disease develops into deadly dengue haemorrhagic fever, which results in bleeding and blood plasma leakage, or dengue shock syndrome, which causes dangerously low blood pressure.
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