Scientists put together an analysis of the possibility of a dengue fever outbreak at the upcoming World Cup in Brazil and say that there is enough of a risk at three locations that there should be a high-alert warning.

They said that at three venues, Recife, Fortaleza and Natal, there should be high-alert warnings, they said in the analysis published in The Lancet Infectious Diseases, reports BBC News. Brazil has had over 7 million reported cases of the mosquito-borne disease since 2000, easily the highest in the world.

Combing through climate data, disease trends and population patterns, scientists predict that those three venues, which are all in the northeastern area of Brazil, will have about 300 cases per 100,000 people, according to CBC News.

University of Toronto infectious disease expert Dr. Jay Keystone said that about 45 out of 1,000 travelers returning from Brazil contract the disease. "Dengue is more common than malaria in Brazil. While we should be aware that there may be increasing rates of infection during FIFA, the endemic rate of infection is already a concern."

The World Cup is being held in June, which comes just after the tail end of the rainy season, which is when the disease is most common since standing water is where it reproduces. Symptoms of dengue fever include headache, fever, fatigue and muscle ache. The infectious disease tends to be more deadly for those who have already had it once.

Transmission of the disease is low though, with Keystone noting, "Only one-third of infected patients get sick. The other two-thirds won't actually have symptoms."

Since there isn't a vaccine or treatment for dengue, prevention is the best option, with it being suggested tourists to Brazil use mosquito repellent, stay in air-conditioned places as best as possible and wear loose clothing.