Aedes aegypti mosquitoes are seen at the Laboratory of Entomology and Ecology of the Dengue Branch of the U.S. Centers for Disease Control and Prevention in San Juan, Puerto Rico, March 6, 2016. REUTERS/Alvin Baez/File Photo

An airplane carrying a banner asking people to use insect repellent to avoid the Zika virus, flies over Miami, Florida, U.S., September 13, 2016. REUTERS/Carlo Allegri

A civil defence member carries an injured girl at a site hit by airstrikes in the rebel-controlled area of Maaret al-Numan town in Idlib province, Syria. REUTERS/Khalil Ashawi

Syrian army soldiers stand at the entrance of the besieged Damascus suburb of Daraya, before the start of evacuation of residents and insurgents of Daraya, Syria August 26, 2016. The Arabic on the wall reads, "Assad's men passed from here". REUTERS/Omar Sanadiki

Musician Keith Richards arrives on the red carpet for the film "The Rolling Stones Ole Ole Ole! : A Trip Across Latin America" during the 41st Toronto International Film Festival (TIFF), in Toronto, Canada, September 16, 2016. REUTERS/Mark Blinch

Musician Keith Richards arrives with his wife Patti Hansen on the red carpet for the film "The Rolling Stones Ole Ole Ole! : A Trip Across Latin America" during the 41st Toronto International Film Festival (TIFF), in Toronto, Canada, September 16, 2016. REUTERS/Mark Blinch

Keith Richards (R) greets fellow bandmate Ronnie Wood on the red carpet for the film "The Rolling Stones Ole Ole Ole! : A Trip Across Latin America" during the 41st Toronto International Film Festival (TIFF), in Toronto, Canada, September 16, 2016. REUTERS/Mark Blinch

Musician Keith Richards arrives with his wife Patti Hansen on the red carpet for the film "The Rolling Stones Ole Ole Ole! : A Trip Across Latin America" during the 41st Toronto International Film Festival (TIFF), in Toronto, Canada, September 16, 2016. REUTERS/Mark Blinch