Brazil is to send more than 600 health workers to Rio de Janeiro state to assist hospitals overflowing with victims of dengue fever, which has killed 49 people in the state in 2008.
Jose Gomes Temporao, the Brazilian health minister, said that 300 additional workers and 15 insecticide spraying vehicles would also be sent to the region.
Dengue fever is spread by the Aedes aegpyti mosquito, which breeds in puddles of stagnant water.
More than 30,000 cases of dengue fever have been confirmed in Rio state this year, with 80 new cases reported every hour.
Patients' complaints
Officials have also opened a crisis centre for officials from the state and federal governments and the armed forces to co-ordinate prevention efforts.
Temporao said the armed forces are to set up field hospitals in the city to receive dengue patients, Reuters reported.
Three hydration tents have also been opened to help treat victims, who frequently suffer from dehydration, AP reported.
Dengue can incapacitate patients for over a week with severe headaches and joint pains, but is not usually fatal. There is no vaccine.
Several patients complained of having to wait in line for hours for treatment and said there weren't enough doctors to assist patients.
"It's absurd, many people are feeling terrible here and they do nothing for us," one patient told Reuters news agency.