Sufferers queue for up to nine hours at Rio's hospitals
The total number of victims is believed to be about 430,000.
Hospital services are being stretched to the limit and health officials have warned that blood banks are running dry due to the increased demand for transfusions.
Dengue, while causing high fevers and severe head and muscle pains, is not usually fatal. But there has been a high incidence of haemorrhagic dengue, a more virulent strain which causes internal bleeding and can kill.
Experts are warning the worst is yet to come.
Thousands of soldiers and firemen have been sent to Rio, and Sao Paolo - where the disease has spread - to fumigate and clear up stagnant water after unusually heavy rains created perfect breeding grounds for the mosquito which carries the dengue virus.
"I felt like my eyeballs would explode. It was the worst pain I ever felt," said a musician, Roberto Pereira, who caught the disease.
Two pop singers had to cancel shows because of dengue and the illness has put almost the entire women's basketball team out of action.
A local newspaper runs daily columns naming celebrities who have been struck down with the disease.
A samba has even been written to teach the public how to ward against the epidemic.
Entitled "Get lost dengue," Telma Tavares' samba croons: "The mosquito bites and it can kill. Empty that bucket, show your will."
Some small companies are warning that, with their staff sick, they may have to stop production.
The outbreak could even have political consequences.
The government is worried that the epidemic could damage the credibility of their candidate for October's presidential election.
Jose Serra, who is the former health secretary and has been blamed by the public after cutting anti-dengue funds, has already been dubbed "presidengue" by the electorate.