Brasilia, Brazil: Some 220,000 soldiers will hand out leaflets door-to-door across Brazil on Saturday, ahead of a massive insecticide-spraying operation as the government tries to stem an outbreak of the mosquito-borne Zika virus.

‘We have to protect the population, especially pregnant women, athletes and tourists who will come for the Olympic Games’ in Rio de Janeiro in August, Defense Minister Aldo Rebelo said at a news conference on Thursday.

Troops will visit three million homes in 350 cities, handing out leaflets explaining that many mosquito breeding areas are found in homes.

For example, mosquito larvae can live in standing water in flower pots.

From Monday to Thursday, 50,000 soldiers accompanied by municipal health workers will spray homes with insecticides and larvicides to kill the Aedes aegypti mosquito which transmits not only Zika virus, but also dengue, chikungunya and yellow fever, Rebelo said.

Rebelo, formerly Brazil’s sports minister, said the government efforts, coupled with winter weather during the Olympics, will ensure that Zika will be not be a problem during the Games.

He added that the military has already sprayed tens of thousands of homes in Sao Paulo state, which has been the hardest-hit by dengue fever, an illness that killed 863 people in Brazil last year.

The South American country has suffered the most cases of Zika in the current outbreak, with 1.5 million people infected since early 2015. On Thursday, the government said it had identified a third death linked to the virus, but stressed it was impossible to say if it was the sole cause.

The vast majority of Zika cases are mild but it has been linked to a rapid rise in the number of children born with microcephaly—abnormally small heads and brains—to mothers infected during pregnancy.

The country has confirmed 404 cases of Zika-linked microcephaly and 3,670 others are under study.

There is currently no cure or vaccine for Zika.