It's a one-day battle in the fight against a tiny enemy: On Saturday, 220,000 Brazilian soldiers are fanning out across the country and knocking on doors to raise awareness about the Zika virus and the mosquito that carries it.

The "Zero Zika" campaign, which The Associated Press calls "unprecedented," aims to reach 3 million homes in 350 cities across Brazil.

Brazilian President Dilma Rousseff is also hitting the ground to spread information, and the AP reports that Rousseff was planning to send cabinet ministers to each of Brazil's 27 states as well.

Doctors and scientists suspect the mosquito-borne Zika virus may be linked to a serious birth defect, microcephaly, as well as a condition called Guillain-Barre syndrome, or GBS, which can cause muscle weakness and paralysis.

An ongoing outbreak of Zika in Latin America began in Brazil last spring. On Friday, Brazilian authorities announced they have confirmed 462 cases of microcephaly since October and they are continuing to examine more than 4,000 reported cases. Brazil usually reports about 150 such cases a year, the AP says.

On Saturday, the World Health Organization said that Brazil, Colombia, El Salvador, Suriname and Venezuela have all reported a rise in GBS "in the context of the Zika virus outbreak."

Links between Zika and microcephaly or Zika and GBS have not been proven. Scientists are racing to understand how Zika works and how it can be prevented or treated.

There is currently no vaccine or treatment.

But one form of prevention is available now: Mosquito control. Zika is carried by Aedes aegypti, the same mosquito that carries dengue, yellow fever and chikungunya.

All day Saturday, Brazil's soldiers will be distributing pamphlets about how to prevent mosquitoes, and the dangers of Zika and other mosquito-borne illnesses.

Brazil's health minister, Marcelo Castro, told the AP on Friday that the war on mosquito-borne illnesses was an old one in Brazil.

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