Mosquito breeding grounds is front line in Zika fight

The Zika virus has been found in more than 25 countries and at least nine cases have been identified in Florida, prompting the governor to declare a health emergency in some areas. Mosquitoes are the main source, but officials say they are investigating a reported case of sexual transmission in Texas. Gwen Ifill talks to Michael Osterholm of the Center for Infectious Disease Research & Policy.