48 hours of symptoms is the ideal time to take those medications. >> sreenivasan: all right, stephen ferrara, columbia university, thanks so much. >> thank you. >> sreenivasan: there is progress in the fight against the zika virus. the virus can cause brain damage in newborn babies, whose mothers are infected by a mosquito bite while pregnant. now researchers in scotland say they have discovered a way to make mosquitoes incapable of transmitting zika and other diseases to humans. itn's peter smith reports. >> reporter: this is wolbachia we"u," a bacteria that could put a stop to the zika virus. it is naturally found in fruit flies, but scientists at glasgow university made an unprecedented discovery when they tried putting it into a mosquito. >> there is variation in efficiency of transmission between the strains but we found one that is more efficient than any we have seen before. >> reporter: how efficient are we talking here? >> we're talk 100% block of the virus getting into the saliva. complete blockage, yes. >> reporter: this 100% success rate is a major step in a fight against the vir

plus, stephen welcomes america ferrara david harbour and musical guest julien baker. featuring jon batiste and stay human. and now, live on tape from the ed sullivan theater in new york city, it's stephen colbert! ( cheers and applause ) ♪ ♪ >> stephen: anniversary nice. lovely. invigorating. hey, everybody! thanks so much. please sit down, folks. ladies and gentlemen, ladies and gentlemen welcome, welcome-- ( cheers and applause ) they're just-- they're just-- they're just screaming to keep warm, you realize. welcome to "the late show," everybody. i'm your host, stephen colbert. and it is great-- ( cheers and applause ) thank you very much. back at you. no, back at you for being here tonight. it's great to be with you, all of you here, together, physically intablght, skin still firmly on our faces. because i bring it up, only because it's a small story-- you may not have heard of it-- tonight we're closer to thermonuclear than last night, which is a fun fact. and it all started on-- new year's day? new year's day. when north korean leader and stackable dictator, kim j