RIO DE JANEIRO, Brazil. A deadly dengue fever epidemic has sickened tens of thousands and claimed at least 80 lives since the start of the year, and it shows no signs of slowing.

Fear of infection has forced thousands of tourists to cancel vacations to the city of Rio de Janeiro and pushed many residents indoors rather than risk being bitten by the striped Aedes aegypti mosquito that transmits the disease.

The epidemic also has collapsed public health services, which are overwhelmed by the crush of patients seeking aid, sparking widespread criticism that government officials were caught unprepared by the outbreak. Last week, the government of Rio de Janeiro state, with a population of 15 million, asked Brazil's military to open three field hospitals.

"There's been a total lack of attention," said Gabriel Fonseca, 41, an electrician who suffers the disease's most serious form, dengue hemorrhagic fever, which can be fatal. Fonseca said he had to wait all night at a city clinic over the weekend to receive hydration treatment that would boost his resistance to the virus.

It has been an embarrassing episode for this city known for its bustling beaches and sporty lifestyle. Now, street vendors sell electrified mosquito racquets - which pop and flash when swatted against a mosquito - instead of soccer jerseys. Gossip columns, instead of listing marriages and break-ups, announce the latest celebrity to be struck by the disease.

The U.S. and other embassies have alerted citizens to take precaution when coming to Rio, and planes proceeding abroad are being sprayed with insecticide.

Children under the age of 16 have been hit hardest by the outbreak, making up nearly half of the state's fatalities. Health officials are investigating 79 more deaths possibly linked to the dengue outbreak.

Dengue fever, which infects about 50 million people around the world a year, has proliferated in dense, growing cities, where sanitation is poor and public health services often have deteriorated, said Josh Ruxin, an assistant clinical professor of public health at Columbia University.

The number of people infected by dengue in Brazil quadrupled from 2004 to 2007, when 560,000 people came down with the disease, according to the Pan American Health Organization.

The details of dengue

- HOW: Transmitted by the bite of a mosquito.

- WHERE: Tropical and subtropical areas.

- WHO: Infants, young children and adults.
- WHAT: Symptoms range from a mild fever to incapacitating high fever, with severe headache, pain behind the eyes, muscle and joint pain, and rash.

Dengue hemorrhagic fever (fever, abdominal pain, vomiting, bleeding) is a potentially lethal complication, affecting mainly children. Early clinical diagnosis and careful clinical management by experienced physicians and nurses increase survival of patients.

- TREATMENT: There is no specific treatment.

World Health Organization