A toddler held by her father swims underwater during a swimming class for babies at Lane Cove pool February 16, 2007 in Sydney, Australia. (Photo by Ian Waldie/Getty Images)

Luxury buildings are reflected in front of houses at a lake dwelling also known as or palafitte or “Palafito” in Recife, Brazil, March 1, 2016. Zika has spread most rapidly in the urban squalor of Brazil's northeastern coastal cities like Recife. (Photo by Ueslei Marcelino/Reuters)

Hindu devotees perform rituals during the Bol Bom pilgrimage, on the outskirts of Kathmandu, Nepal, Monday, August 8, 2016. During this pilgrimage, devotees walk miles barefooted before offering water collected from Bagmati river, at the Pashupatinath temple in Katmandu. Shravan Somwar or Monday of Hindu calendar month of Shravan is considered auspicious for offering prayers to Lord Shiva, the god of destruction. (Photo by Niranjan Shrestha/AP Photo)

Waves hit the seawall during heavy seas and high winds in Dawlish in south west Britain, February 2, 2017. (Photo by Toby Melville/Reuters)

Eritrean refugee children play at Mai-Aini refugee camp near the Eritrean boarder in the Tigrai region in Ethiopia February 10, 2016. Each month as many as 5,000 people flee Eritrea according to U.N. figures, estimates the Eritrean government disputes. The government puts the population at about 3.6 million, while other estimates suggest it could be almost double that. (Photo by Tiksa Negeri/Reuters)

Syrian refugees covered with dust arrive at the Trabeel border, after crossing into Jordanian territory with their families, near the northeastern Jordanian border with Syria, and Iraq, near the town of Ruwaished, east of Amman September 10, 2015. (Photo by Muhammad Hamed/Reuters)

Internally displaced Syrian children play inside a refugee camp in the Hama countryside, Syria January 1, 2016. (Photo by Ammar Abdullah/Reuters)

Internally displaced people who fled flooding of the overflowed Shabelle river rest after receiving relief assistance near Baledweyne town in central Somalia, June 22, 2016. (Photo by Feisal Omar/Reuters)