dr. besser on this again tonight. dr. besser, thank you. >>> we turn now to a health skarl out of texas we're following. an apparent gas leak at a middle school. more than 100 students and teachers evacuated. some taken out of stretchers, whisked to the hospital. abc's ryan owens in dallas tonight, where there were no warning signs until students and staff began falling ill. >> reporter: for more than 100 students and staff at this texas middle school, their school day ended at the hospital. being checked out for symptoms of carbon monoxide poisoning. >> showed symptoms of nausea and headache and some were vomiting and, of course, ems treated and took the appropriate medical action. >> reporter: some students left on stretchers. others loaded into buses to a local hospital. >> everyone didn't really know how to react to it, because this never happened before. >> reporter: the fire chief in the city of beaumont, east of houston, believes the gas was leaking from a boiler at marshall middle school. the leak was first reporte

((sot)) dr besser "now, take a look at this map. that mosquito is found in every country in the western hemisphere except for canada and chile." ((nat)) from brazil gov youtube clip with more than a million people been hit especially hard. in an effort to show how they're aggressively responding, the brazilian government posted this video on youtube showing workers spraying and fighting mosquitos carrying the virus. according to the c-d- c.. so far.. only a handful of cases have been identified in the u-s. ((sot)) dr besser "they say we're going to see small outbreaks due to people coming back from countries who are infected." the virus isn't known to spread from person to person.. and the symptoms for most people... fever, rash, joint pain and red eyes... are mild and pass without incident. but the virus could cause life-threatening brain damage in unborn babies?so u-s officials are urging expecting moms to stay away from countries where there are infections. ((sot)) dr besser "if you're pregnant the cdc says don't go. for other pe

dr besser: "now, take a look at this map. that mosquito is found in every country in the western hemisphere except for canada and chile." people infected, brazil has been hit especially hard. in an effort to show how they're aggressively responding, the posted this video on youtube showing workers spraying and fighting mosquitos carrying the virus. according to the c-d-c.. so far.. only a handful of cases have been identified in the u-s. dr besser: "they say we're going to see small outbreaks due to people coming back from countries who are infected." the virus isn't known to spread from person to person.. and the symptoms for most people... fever, rash, joint pain and red eyes... are mild and pass without incident. but the virus could babies?so u-s officials are urging expecting moms to stay away from countries where there are infections. dr besser: "if you're pregnant the cdc says don't go. for other people if you go, use repellant to reduce the chances you'll get bit." there is no vaccine or drugs to prevent or treat the i

((sot)) dr besser "now, take a look at this map. that mosquito is found in every country in the western hemisphere except for canada and chile." ((nat)) from brazil gov youtube clip with more than a million people infected, brazil has been hit especially hard. in an effort to show how they're aggressively responding, the brazilian government posted this video on so far.. only a handful of cases have been identified in the u-s. ((sot)) dr besser "they say we're going to see small outbreaks due to people coming back from countries who are infected." the virus isn't known to spread from person to eyes... are mild and pass without incident. but the virus could cause life- threatening brain damage in unborn babies?so u-s officials are urging expecting moms to stay away from countries where ((sot)) dr besser "if you're pregnant the cdc says don't go. for other people if you go, use repellant to reduce the chances you'll get bit." elizabeth tag: there is no vaccine or drugs to prevent or treat the infection.. so if you think you have any o

((sot)) dr besser "now, take a look at this map. that mosquito is found in every country in the western hemisphere except for canada and chile." ((nat)) from brazil gov youtube clip with more than a million people infected, brazil has been hit especially hard. in an effort to show how they're aggressively responding, the brazilian government posted this video on youtube showing workers spraying and fighting mosquitos carrying the virus. according to the c-d-c.. so far.. only a handful of cases have been identified in the u-s. ((sot)) dr besser "they say we're going to see small outbreaks due to people coming back from countries who are infected." the virus isn't known to spread from person to hout incident. but the virus could cause life- threatening brain damage in unborn babies?so u-s officials are urging expecting moms to stay away from countries where there are infections. ((sot)) dr besser "if you're pregnant the cdc says don't go. for other people if you go, use repellant to reduce the chances you'll get bit." elizabeth tag: t

dr. besser, with your questions answered. >>> two storms hitting this weekend. the dangerous moment on the highway already. >>> and the new headline coming out of the nfl tonight on concussions. coming amid a controversial claim about o.j. simpson. >>> good evening. we begin tonight with two major developments in the race for 2016. the two front runners on each side. three days to go now until iowa. hillary clinton, and the bombshell reveal from the statement department today. 22 e-mails from her private server have been labeled as top secret. and trump, a no-show last night. will he pay any price, or will >> reporter: tonight, ted cruz reeling after the debate, and donald trump trying to take him out, calling the canadian-born senator an "anchor baby." >> now ted cruz may not be a u.s. citizen, right? but, he's an anchor baby. no, he's an anchor baby. ted cruz is an anchor baby in canada. >> reporter: and cruz refusing to return fire. >> he's welcome to say whatever he likes. i like and respect him. >> reporter: but trump is a hard candidate to ignore. >> let's

dr. besser tonight, joining us from brazil. and first, rich, let's tackle what people back here in the u.s. are concerned about. if a neighbor comes home from one of these regions with the zika virus, can they then pass it to their neighbors? >> reporter: well, they can. if they come back and they're infected and a mosquito bites them, that mosquito can bite other people and infect them. if you have any symptoms when you return, see your doctor. >> and tell your family and the repellant, too. and you pointed out, rich, that pregnant women need to be most concerned. how long does the virus stay in the system and can it affect a future pregnancy? >> reporter: well, if you look at similar-type viruses, what they find is, when a person recovers from that infection, after about a week or so, and their symptoms are gone, the virus is out of their body. so, scientists don't believe that future pregnancies are going to be at any risk at all. just the current one, when you're infected. >> dr. besser on this again tonight. >>> we turn no

dr. besser, thank you. >>> to the economy back at home this evening. stocks roaring back, ending the week and the month with a rally. closing up near 400 points. but stocks still down for the month of january. >>> still much more ahead on "world news tonight." the major headline coming out of the nfl. it comes amid another controversial claim about o.j. simpson. >>> and also, two major systems we're watching this weekend. the danger on an american highway already. >>> dramatic video. the takedown at a cracker barrel. customers stunned as police storm in. >>> and the surprise behind the surprise. olympic hero michael phelps talking about why he showed up at a game to distract a player. and did it work? we'll be right back. what if one sit-up could prevent heart disease? one. wishful thinking, right? but there is one step you can take to help prevent another serious disease. pneumococcal pneumonia. if you are 50 or older, one dose of the prevnar 13® vaccine can help protect you from pneumococcal pneumonia, an illness that can cause coughing, chest pain,

dr besser: "now, take a look at this map. that mosquito is found in every country in the western hemisphere except for canada and chile." with more than a million people infected, brazil has been hit especially hard. in an effort to show how they're aggressively responding, the brazilian government posted this video on youtube showing workers spraying and fighting mosquitos according tohe c-d-c.. so far.. only a handful of cases have been identified in the u-s. dr besser: "they say we're going to see small outbreaks due to people coming back from countries who are infected." the virus isn't known to spread from person to person.. and the symptoms for most people... fever, rash, joint pain and red eyes... are mild and pass without incident. but the virus could cause life-threatening brain damage in unborn babies?so u-s officials are urging expecting moms to stay away from countries where there are infections. dr besser: "if you're pregnant the cdc says don't go. for other people if you go, use repellant to reduce the chances y

dr. richard besser is in rio de janeiro. dr. besser: so far, more than 1.5 million cases, more than 4000 babies on with severe brain damage. kenneth: pregnant women have been told to postpone travel to affected areas. zika is not contagious person to person, but there is still a risk. dr. besser: if someone is infected and comes back to the united states and is bit by a mosquito, that mosquito can bite other people and be infected. kenneth: in the u.s. territory of puerto rico, about 20 reported cases of zika. health officials are warning people to use bug repellant and mosquito nets over beds. dr. schuchat: mosquito control is pretty difficult. the mosquitoes that are the daytime, and they' re pretty aggressive biters. kenneth: more airlines and latin america are offering refunds to pregnant women. people who traveled to affected areas and have mild symptoms of s are being told to get checked immediately. kenneth moton, abc news, washington. erin: right now, police are connection to a shooting in manchester. considered armed and

dr. besser standing by. >>> and, will smith on his oscar boycott. great to have you with us. 75 million americans are under winter weather alerts. blizzard warnings already. and the first test in washington, d.c., a disaster on the road. just an inch of snow on the roads, the interstate turned into a parking lot.t. this i ibefore the next major storm, bringing two feet off snow in some places. here's the storm track. several states and major cities in the path. we begin with david kerley in washington, where it could be historic. >> reporter: tonight, with a major storm bearing down, a test failed. all the spinning, sliding, smashing, turning the nation's capital into a nigthmare. pedestrians too. watch this woman. highways became parking lots. sitting in his car, will lee is him. not once, but twice. now, up to two feet of snow and blinding winds are hours away. it was forecasted, but many local areas didn't salt the roads. >> there's just crashes all over the place. >> reporr: slick roads and not enough snow crews working. leading to an embarrasse

dr. besser. what's the risk of this spreading in the u.s. now? >> well, if someone is infected and then bitten by a mosquito, they need to be told to use repellents. there could be small clusters here. >> dr. besser, thank you. >>> and there's much more ahead on "world news tonight" this thursday. the deadly bank heist in the heartland. the gunman opening fire, taking a hostage, leading police on a wild chase. we'll tell you how it ended. >>> there's also news about a missing toddler, vanishing last week in the brutal cold. hundreds searching for the little boy. >>> and robin roberts with will smith. what he's now saying about hollywood, race, and his own wife's oscar boycott. that's all coming up tonight. one. wishful thinking, right? but there is one step you can take to help prevent another serious disease. pneumococcal pneumonia. if you are 50 or older, one dose of the prevnar 13 vaccine can help protect you from pneumococcal pneumonia, an illness that can cause coughing, chest pain, difficulty breathing, even if you have already been vaccina

dr. richard besser at ground hours north by plane. up to the place believed to have the highest concentration of zika cases in the world. we put on repellent to protect from mosquitos. here at the medical center, they're treating more and more patients. >> first, we were shocked to find babies born with micro microcephaly. it was a surprise not only for the doctors, but for the mothers. >> reporter: elena has difficulty hearing, but does well in vision tests. little is known about the zika virus. scientists trying to answer the big question here, how closely and babies linked? outside, soldiers are going door to door, trying to show brazilians how to get rid of mosquitos. crews straying in neighborhoods. >> so let's get right to dr. besser, joining us now from brazil. how long does the virus generally stay in your system? >> only for one or two weeks, and the infection is mind. but they'll be monitoring babyies to make sure they're developing normt normally. >>> and stocks ending with a rally, closing up near 400 points. but stocks st