Sao Paulo: Three Brazilian host cities Fortaleza, Natal and Recife are at higher risk than the other nine of a dengue fever outbreak during the World Cup, scientists said on Saturday.
In absolute terms, the risk is low in all Cup venues, but comparatively greater in the three northeastern cities and authorities should beef up steps to prevent an outbreak, they said.
A potentially dangerous fever caused by a virus for which there is no vaccine or cure, dengue is transmitted by the Aedes aegypti mosquito when it takes a blood meal.
Doctors last year sounded the alarm over dengue at the June 12-July 13 tournament. The disease is endemic in Brazil, which is expected to lure hundreds of thousands of football visitors.
Writing in the journal The Lancet Infectious Diseases, a team of European and Brazilian experts crunched the numbers to pinpoint areas of risk.
They looked at real-time weather patterns provided by four meteorological agencies, particular rainfall which affects mosquito breeding.
They matched these against 13 years of data from prior dengue outbreaks in the month of June in 553 “microregions” of Brazil, including the 12 tournament host cities.
The researchers factored in the dynamics of how a dengue outbreak builds up.
It takes between seven and 14 days for a mosquito to become infectious with the virus it has picked up from a human. And when the insect bites another human, the virus needs four to seven days to incubate.
Visitors are not expected to stay in the same city for more than two or three weeks, which means an epidemic must already be well underway for large numbers to be vulnerable in June.