The Zika virus is spreading "explosively" across Latin America and the Caribbean, and the city of Recife in northeastern Brazil remains a hotbed. The city's slums are particularly vulnerable to the mosquito-borne disease. There, the lack of screens and air condtioning puts the poorest residents at greater risk of encountering a Zika-carrying pest.

About 80 percent of Zika victims show no symptoms at all, but that's little consolation for Brazil's estimated 400,000 pregnant women, as health officials believe Zika could be responsible for birth defects.

"Many pregnant women are scared," says Brazilian photojournalist Felipe Dana, who took these photos.

Those who do give birth to disabled children often "really struggle," Dana adds. Because of the amount of care the infants need, the women often can't return to work. That can cause severe financial strain.

In response to the emerging threat of Zika, Brazil's health minister, Marcelo Castro, has ordered nearly 220,000 members of the country's military to go door-to-door in mosquito eradication efforts.

Still, the country is "badly losing the battle" against the Aedes aegypti mosquito—which also spreads dengue, chikungunya, and yellow fevers—says Castro. Researchers have also reported one case of Zika they believe was sexually transmitted.