Sao Paulo resident Juliana Matuoka always thought her stunning tropical flowers were something to appreciate from afar. Now, however, they are enemy territory.

"Here, I got one!" exclaimed Marcio Hoglhammer, a municipal health department worker who arrived along with colleagues and two young soldiers as part of Brazil's massive house-to-house effort to eradicate the Zika virus and dengue-carrying mosquitoes.

Hoglhammer reached into the huge leaves of the bromelia flowers and used a syringe to suck out water, then held it up triumphantly.

"I found larvae of the Aedes aegypti (mosquito)," he said. "This plant was a real incubator."

As Matuoka looked on in surprise, the health agent explained that mosquitoes are more likely to breed in certain plants than others. "They don't need a jungle for this, but they do need certain plants," he said.

"So I recommended that if they don't pay attention to this plant, then better to change it to something else."

The mosquito hunters were working their way through the upscale neighborhood of Alto Pinheiros in the west of Brazil's biggest city, stopping at Matuoka's house because she recently contracted dengue fever.

Checks have long been made in an effort to prevent dengue. But with national and international concern growing over the explosion in the region of Zika cases, the mosquito-checking program has taken on new urgency.

Matuoka, who has an art gallery, said she had no idea that bromelias could be part of a problem sending tremors across the continent.

Although nearly all Zika cases result in nothing more than the mildest symptoms, there are concerns that Zika can cause serious birth defects in babies born to infected mothers and also cause a rare, sometimes deadly disorder called Guillain-Barre syndrome in adults.

Brazil is pouring considerable resources into what President Dilma Rousseff calls a "war" against mosquitoes.

Officials say that simply ridding houses and public areas of standing water, where mosquitoes like to breed, will strike a major blow.

In some places, including future Olympic sites in Rio de Janeiro, heavy spraying and fumigating is planned.

The health ministry says more than 30 percent of Brazilian homes -- about 20.7 million in total -- have already been visited by soldiers and healthcare workers to make checks and inform residents.

In just one day, Hoglhammer recently managed to visit 300 houses, he said. But in a country of 204 million people at the height of Tropical summer, with mosquitoes everywhere, the end to the battle is not in view.

"I don't know if we're advancing much," he said.