The number of syphilis cases in the United States is the highest it's been since the 1950s, according to the Centers for Disease Control and Prevention. Dr. Philip Chan, chief medical officer for Open Door Health and an associate professor at Brown University, joins Ali Rogin to discuss what's behind the surge and what public health officials are doing about it. PBS NewsHour is supported by - https://www.pbs.org/newshour/about/funders