In this July 24, 2016 photo, a pilgrim takes a bath in a sacred mud pool during the annual Voodoo celebration in Plaine-du-Nord, Haiti, Saturday, July 23, 2016. Pilgrims come to bathe in the mud and make offerings expecting a miracle. (Photo by Dieu Nalio Chery/AP Photo)

People look at a man, who residents said was killed by al Qaeda militants, hanging on a bridge in Yemen's southeastern city of Mukalla June 17, 2015. Al Qaeda militants in Yemen killed two alleged Saudi spies, residents said, accusing them of planting tracking devices which enabled the assassination of the group's leader in a suspected U.S. drone strike. (Photo by Reuters/Stringer)

The waning moon sets behind leafless sumac trees on a crisp, clear morning, Thursday, December 15, 2016, in Portland, Maine. Much of the northern Mid-Atlantic and Northeast will stay cold for the next couple of days as the arctic air remains stuck over the northern Appalachians, the National Weather Service said. (Photo by Robert F. Bukaty/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)

Almost two years old male baby orang-utan Dalai looks on in the zoo in Dresden, Germany, 30 March 2017. Dalai was born to mother Daisy in June 2016. (Photo by Filip Singer/EPA)

In this June 12, 2017 photo, a woman stands in front of a mural on the slope in Central district, Hong Kong. Once known as Victoria after the British queen, Hong Kong island's waterfront formed the core of the British settlement after Hong Kong island was handed over as a colony in 1842. Today as Hong Kong approaches the 20th anniversary of its return to China, it remains a bustling commercial and financial center as well as the location of the main government offices. However, along the streets that angle sharply upward toward the mountains above, a more relaxed pace of life endures. (AP Photo/Kin Cheung)

A mouse rides on the back of a frog in floodwaters in the northern Indian city Lucknow June 30, 2006. (Photo by Pawan Kumar/Reuters)

Archive: A group of people dressed as Santa Claus wait for the bus on December 1960, London, England. (Photo by Keystone-France/Gamma-Keystone via Getty Images) Modern Day: Passengers wait for busses in Holborn on November 24, 2017 in London, England. (Photo by Chris J. Ratcliffe/Getty Images)