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Dengue fever has swept across Brazil, reaching epidemic proportions in at least nine states, with São Paulo the worst affected by far. Officials say nearly 746,000 cases of the deadly virus were confirmed as of April 18, 2015.

Over half of confirmed cases were recorded in São Paulo state, the country's most populous, which registered 402,000 cases — almost three times as many cases as last year.

São Paulo is also leading in fatalities, recording 169 of the 229 dengue-related deaths in the first four months of the year. In 2014, the country saw 158 deaths in the same period.

The severe hemorrhagic form of dengue fever decimates the level of platelets in the bloodstream. The illness can cause blood to seep from the body, blood pressure to drop, and breathing to become difficult.

The number of cases in Brazil is now 367.8 per 100,000 inhabitants. The epidemic threshold set by the World Health Organization is 300 cases per 100,000 residents.

'In my house alone, both my mother and brother have dengue, and it's the second time my brother has caught it.'

Some officials played down the idea of a nationwide epidemic, blaming municipalities with extreme levels of dengue — such as Brasilândia in São Paulo, which has seen 1,880 cases per 100,000 inhabitants — for pushing up averages.

But Health Minister Arthur Chioro said the whole country was battling dengue. "We have 745,957 cases to April 18. We know this number will increase," Chioro was quoted by Agência Brasil news agency as saying."Brazil is living an epidemic situation focused in nine states." He added that a lower number of cases in 2014 led to officials taking an "overly relaxed" approach for this season.

The result is being felt in hospitals throughout the country, and many have been bursting with patients displaying classic dengue symptoms — severe fevers, headaches, pain behind the eyes and in the joints, and abdominal cramps.

"In my house alone, both my mother and brother have dengue, and it's the second time my brother has caught it," Leonardo Almeida Oliveira, a 20-year-old student from Embu das Artes in São Paulo, told VICE News. "He went to the local public hospital and waited over four hours to be seen. Many waited longer and gave up, going home untreated."

Bronislawa Ciotek de Castro, who coordinates São Paulo's fight against dengue at the Secretary of Health, said a team of 2,500 dengue inspectors are working alongside biologists and hospital staff to combat dengue.

"As most cases of dengue occur inside people's houses, this has to be a joint effort and we have to rely on the public's help," she told VICE News.

A government poster campaign in the São Paulo subway gives Brazilians a checklist to see if there house is at risk of hosting dengue-carrying mosquitoes. (Photo by Ben Tavener)

The government has worked to inform people how to reduce potential breeding grounds for the Aedes aegypti mosquito, which transmits the virus.

The government has launched a public education campaign, turning to TV and radio channels, public buildings, social media, and public transport in and around São Paulo to raise awareness about the epidemic. Some municipalities have even given vendors special aprons to wear featuring slogans urging locals to fight dengue.

The messages concentrate on reducing accumulations clean, stagnant water, which are the key breeding grounds for the mosquito: "Remove the saucer under that flowerpot!" — "Make sure that water tank is covered!" — "Drill holes in any unused tires!"

Brazilians are even taught to recognize the offending species of mosquito by the white patches on its legs.

But despite the government's efforts, many reports have surfaced of inspectors being hampered from conducting crucial house-to-house inspections.

Oliveira said that inspectors don't get access to everyone's home.

"People are often out at work or some outright refuse to let the inspectors in or just pretend to be out, fearful something will be found that is wrong and that they'll be fined," he told VICE News, adding that the teams who are meant to follow up with insecticides have rarely been seen in his area.

In April, the army was also called in to accompany dengue inspectors as they attempted to rid some of São Paulo's more violent areas of potential breeding grounds for mosquitoes.

Experts say the explosion of the dengue-carrying insects is the result of extremely hot temperatures over the last two years and Brazilians beginning to store water in any way they can due to the ongoing drought, particularly the populous southeast.

"There are huge swathes of the population storing water at homes, creating more breeding grounds," Jan Carlo Delorenzi, professor of immunology and public health at São Paulo's Mackenzie Presbyterian University, told VICE News.

"But the government's response also has been sluggish. They waited until the problem was already here before launching their major information campaign," he said. "Really, they should be doing that in the cooler seasons, so that the breeding grounds are already dealt with when summer arrives."

Delorenzi called the scale of the epidemic "simply unacceptable in 2015" given the country has seen epidemics and endemics of dengue since the second half of the 19th century.

"It makes you ask the question: 'What are we missing?' We've eradicated dengue before, so we can do it again. We just need there to be a concerted effort between both the population and the authorities," he said.

Scientists and government authorities are developing other innovative techniques to tackle dengue.

One technique introduces transgenic mosquitoes, which breed a "genetic timebomb" into the males, which kills their offspring to die before reaching maturity. Another uses a bacteria, Wolbachia, which prevents mosquitoes from becoming infected in the first place.

However, higher hopes are pinned on inoculating the population: Scientists in Brazil are in the final stages of developing a dengue vaccine that could immunize humansagainst the four strains commonly found in the country.

Indeed, São Paulo state health secretary David Uip told the Folha de S.Paulo that Brazil's best bet lay with a new vaccine, although it would be ready "at best in 2016".

"The only way to control dengue will be with the vaccine," Uip said."The municipalities have worked very hard, but sometimes you do all you can and it's still not enough."

With winter temperatures now arriving in São Paulo and other parts of Brazil, the number of new dengue cases should now start to fall away — but, many fear, only until the heat and rain of the Brazilian summer return.