Brazilian teams are on alert because of a dengue fever outbreak that has already affected some of the country's top clubs. Three players were diagnosed with the mosquito-borne disease this week, including Corinthians striker Paolo Guerrero. Players have been forced to use insect repellent during practice sessions and clubs have asked health officials to check their training centres for mosquito breeding sites. Brazilian football clubs have been put on alert after a dengue fever outbreak . In addition to Guerrero, Palmeiras reserve goalkeeper Aranha and young Santos striker Leo Cittadini also have been diagnosed with the disease and won't be able to help their teams in the final stages of the Sao Paulo state championship this month. 'We have to find a way to stay away from this little mosquito,' Palmeiras midfielder Arouca said. Guerrero, Corinthians' top striker, will also miss his team's last two games in the group stage of the Copa Libertadores, Latin America's top club tournament. The Peruvian has been hospitalized since Saturday and there is no word on when he will be released. Corinthians striker Paolo Guerrero is one of three players that have already been diagnosed . The players affected will need about two weeks to fully recover from the disease, which causes extreme joint pain and headaches. There is no cure, but is rarely fatal. Cases of dengue fever have increased significantly across Brazil this year, with most of them reported in Sao Paulo state. Brazil's health ministry said there have been more than 460,000 cases of the disease in the country in 2015, which accounts for almost 5,000 cases a day. More than 130 people have died so far this year, the ministry said. Corinthians midfielder Renato Augusto said some players have been practicing with pants and long sleeves to try to avoid the mosquitoes. 'We are afraid, of course,' he said. 'It turns out it's not only the defenders we have to worry about these days.' Guerrero, who used to play for Bayern Munich, in action for Corinthians in a Copa Libertadores match . Another Corinthians player, defender Rodrigo Sam, was hospitalized for two weeks after getting the disease earlier this year. Health officials inspected Corinthians' training center this week and said there were no signs of breeding sites for mosquitoes carrying dengue. The popular Brazilian club said the players were likely infected while away from the team's premises. Still, doctor Ivan Grava said players would continue to use insect repellent and, when possible, the team would not practice during times mosquitoes were more likely to appear. Another top Brazilian club affected by dengue fever this year was Sao Paulo. One of the team's doctors had the disease, and players recently expressed their concern about having to play a match in a city where the disease had spread quickly.
Brazilian teams are on alert because of a dengue fever outbreak .
The mosquito-borne disease has already affected some top clubs .
Corinthians striker Paolo Guerrero one of three players diagnosed .