Pakistani schoolgirl Malala Yousafzai, the joint winner of the Nobel Peace Prize, speaks at Birmingham library in Birmingham, central England, in this October 10, 2014 file photo. (Photo by Darren Staples/Reuters)

A health worker wearing a protective suit stands near a window at an isolation ward on the sixth floor of Madrid's Carlos III Hospital, in this October 12, 2014 file photo. (Photo by Paul Hanna/Reuters)

Ultra-Orthodox Jewish boys climb down a wall near the scene of a suspected attack in Jerusalem, in this August 4, 2014 file photo. (Photo by Ammar Awad/Reuters)

Arthur Abele of Germany competes in the men's shot put decathlon during the European Athletics Championships at the Letzigrund Stadium in Zurich, in this August 12, 2014 file photo. (Photo by Phil Noble/Reuters)

Displaced people from the minority Yazidi sect, fleeing violence from forces loyal to the Islamic State in Sinjar town, walk towards the Syrian border, on the outskirts of Sinjar mountain, near the Syrian border town of Elierbeh of Al-Hasakah Governorate, in this August 11, 2014 file photo. (Photo by Rodi Said/Reuters)

A woman reacts near a damaged multi-storey block of flats following what locals say was recent shelling by Ukrainian forces in Donetsk, in this August 13, 2014 file photo. (Photo by Sergei Karpukhin/Reuters)

Men sleep covered with a mosquito net on a bridge above a train station outside Yangon, in this August 20, 2014 file photo. (Photo by Soe Zeya Tun/Reuters)

A man is doused with milk and sprayed with mist after being hit by an eye irritant from security forces trying to disperse demonstrators protesting against the shooting of unarmed black teen Michael Brown in Ferguson, Missouri, in this August 20, 2014 file photo. (Photo by Adrees Latif/Reuters)

Shi'ite volunteers, who have joined the Iraqi army to fight against militants of the Islamic State, formerly known as the Islamic State of Iraq and the Levant (ISIL), take part in field training in Najaf, in this August 20, 2014 file photo. (Photo by Ahmad Mousa/Reuters)

Health workers wearing protective clothing prepare to carry an abandoned dead body presenting with Ebola symptoms at Duwala market in Monrovia, Liberia, in this August 17, 2014 file photo. (Photo by Reuters/2Tango)

A Palestinian reacts during the funeral of three senior Hamas commanders, who were killed in an Israeli air strike, at a mosque in Rafah in the southern Gaza Strip, in this August 21, 2014 file photo. (Photo by Ibraheem Abu Mustafa/Reuters)

Kent Brantly, who contracted the deadly virus Ebola, looks at his wife Amber during a news conference at Emory University Hospital in Atlanta, Georgia, in this August 21, 2014 file photo. (Photo by Tami Chappell/Reuters)

Dawn Harper-Nelson (C) of the U.S. celebrates winning the women's 100m hurdles event of the Weltklasse Diamond League meeting at the Letzigrund stadium in Zurich, in this August 28, 2014 file photo. (Photo by Arnd Wiegmann/Reuters)

A grave cleaner holds the mummified body of a woman during exhumation works at the Verbena cemetery in Guatemala City, in this April 17, 2013 file photo. (Photo by Jorge Dan Lopez/Reuters)

A Pro-Russian separatist stands near the damaged war memorial at Savur-Mohyla, a hill east of the city of Donetsk, in this August 28, 2014 file photo. (Photo by Maxim Shemetov/Reuters)

A driver sits inside a bus during an exchange of prisoners-of-war (POWs) near Donetsk, eastern Ukraine, in this September 21, 2014 file photo. (Photo by Marko Djurica/Reuters)

Models, including Kendall Jenner, present creations from the Dolce & Gabbana Spring/Summer 2015 collection during Milan Fashion Week, in this September 21, 2014 file photo. (Photo by Stefano Rellandini/Reuters)

A school official takes a pupil's temperature using an infrared digital laser thermometer in front of the school premises, at the resumption of private schools, in Lagos, in this September 22, 2014 file photo. (Photo by Akintunde Akinleye/Reuters)

A protester (C) raises his umbrellas in front of tear gas fired by riot police to disperse protesters blocking the main street to the financial Central district outside the government headquarters in Hong Kong, in this September 28, 2014 file photo. (Photo by Tyrone Siu/Reuters)

Police officers sleep as protesters (not pictured) block the main street to the financial Central district outside the government headquarters in Hong Kong, in this September 29, 2014 file photo. (Photo by Carlos Barria/Reuters)

India's Prime Minister Narendra Modi gestures while speaking at Madison Square Garden in New York, during a visit to the United States, in this September 28, 2014 file photo. (Photo by Lucas Jackson/Reuters)

U.S. actor George Clooney and his wife Amal Alamuddin arrive at Venice city hall for a civil ceremony to formalise their wedding in Venice, in this September 29, 2014 file photo. (Photo by Alessandro Bianchi/Reuters)

Jiejin Qiu, who is six months pregnant with her first baby, poses underwater during a photo shoot at a local wedding photo studio in Shanghai, in this September 5, 2014 file photo. (Photo by Carlos Barria/Reuters)

Health workers attend a protest outside La Paz Hospital, calling for Spain's Health Minister Ana Mato to resign after a Spanish nurse contracted Ebola, in Madrid, in this October 7, 2014 file photo. (Photo by Andrea Comas/Reuters)

Neighbors watch a man in a hazardous material suit work on cleaning the apartment unit where a man diagnosed with the Ebola virus was staying in Dallas, Texas, in this October 6, 2014 file photo. (Photo by Jim Young/Reuters)