breaking public health scare. a confirmed case of mad cow disease in california has the agriculture department here in washington on full alert. the fatal brain disease not only can be passed among cattle, scientists think an equally deadly variation can be transmitted to humans who eat contaminated beef or dairy products. the first confirmed case here in the united states in six years. elizabeth cohen joins us from the cnn center in atlanta. elizabeth, one of the reasons people get so scared is the potential. what does this mean for the food supply? >> you know, for this one cow that really -- this one cow doesn't have that much importance for our food supply. the usda doesn't appear to be panicked, even critics of the usda don't appear to be tank panicked. the reason why is this cow was never going to be eaten, it was a dairy cow. and experts say milk of an infected cow is not infectious. you can't get the disease from drinking the milk. john. >> how did they find out that this cow was sick? >>y don't know in this case but usually a cow stumbles around and so they examine the cow and find out they're sick or perhaps the cow has died unexpectedly and they find out upon examination that the cow is sick. >> and you know firsthand what can happen if, a big if, eats infected meat and gets the human form of mad cow disease. tell us about the woman you interviewed. >> in 2006 i entered a woman named charlene who contracted mad cow disease in the united kingdom but didn't know it. she didn't get sick immediately. she came to this country. you can see she was incredibly ill and died just a few months after she did that story. the median incubation period for this disease is 15 years, so you eat the infected meat and 15 years pass until you have your symptoms. then once you're sick, there is really nothing that doctors can do. it was devastating to see this woman, john. >> elizabeth cohen, thanks so much. in about ten minutes we'll have an exclusive conversation with thing a -- ag secretary, tom vilsack, here in just a few moments. now to other news breaking, still more resignations in the secret service prostitution scandal. dana bash has the latest on that. >> reporter: that's right, john. tonight two more secret service members have been forced to resign. one had his security clearance permanently revoked, which effectively means that his career would ultimately be over if that stays. and two were cleared of serious charges. so what this means is that the secret service investigation of the 12 members of its organization that were a part of the initial investigation, they have all been dealt with. let me give you a broad pick tut -- picture of the secret service scandal. 12 of been investigated. eight have been forced out. one is in the process of being forced out. that's what was when you lose your security clearance, although he could appeal. three all told have been cleared of serious charges but they could face -- two of them could face lesser sanctions or punishment. so they certainly move swiftly inside the secret service to deal with. this maybe not as swifty as some would have liked but it is not a good day or couple of weeks for this agency. >> the follow-up question to that point, the congressional hearings are coming pretty soon. has the swiftness of the investigation convinced people that the management of the agency, the secret service, has its act together? >> so far the answer is yes. being in washington for a long time as you have as well, it's stunning. usually the way scandals work here in washington is people here in congress immediately call for somebody at the helm of the agency to go. not in the case of secret service director mark sullivan. i've talked to democrats and republicans at the top of the key committees, house and senate. they say for right now they feel confident that he is the right person to stay in this job, but the investigations here in congress, they're just starting, john. >> congressional correspondent dana bash with more breaking details. thanks. we'll have more at the bottom of the hour. moving on to stinging new testimony in the trial of john edwards. he's accused of illegally using campaign money to hide his mistre mistress's pregnancy. a former aide took the stand recount the moment john edwards found out about the pregnancy. that witness, andrew young, excuse my language, says his boss called the mistress a quote, crazy slut and said there was just a one in three chance the child was his. joe johns was in the courtroom in greensboro today. as you listen to andrew young's testimony, what was the most damaging part? >> reporter: well, that certainly was the most memorable, i think, from the entire day. because it shows a callous side of john edwards, but on the other hand there was some testimony from andrew young that really sort of suggested john edwards was living in a dream world, believing that all of this information about, you know, his girlfriend, the baby and so on was just going to blow over, if you will. a good example of that came around december 14th. this is something andrew young testified to. he said that when he was asked if john edwards was kept apprised of all the money that was coming in to pay to cover up this affair, he said no, we sort of talked in code. edwards really didn't want to know about it in case he had to be sworn in as attorney general. so that sort of shows you the state of mind, if you believe andrew young, that john edwards was in at the time leading right up to the 2008 primary in iowa, you know, the caucuses in iowa and the primaries, john. >> that's stunning testimony. joe, thanks so much. we once had tonight circled as a major showdown night in the republican race. republicans, mitt romney, rick santorum, facing off in santorum's home state of pennsylvania. senator santorum now gone from the race so, yes, there is less drama. it's nonetheless a major turning point in the race. five states are voting today, pennsylvania, delaware, new york, connecticut and rhode island. here's why it matters. let's look up here. let's take a look at this. governor romney enters the night by our estimate at cnn, 695 delegates. needs to get to 1144. if you notice, speaker gingrich is still in the race. he's in the 140s somewhere. ron paul is only half that. santorum now out of the race. so governor romney with appear overwhelming lead. we are assuming governor romney will win roughly two-thirds of the delegates tonight. if he wins all five states, he gets to 875. not all the way to the finish line but look how much ahead of speaker gingrich and congressman paul. so much ahead that speaker gingrich is now saying if he doesn't win delaware or do very, very well, he will reassess his candidacy. speaker gingrich now talking about getting out. a quick point, governor romney can't get to this magic number until the end of may. since he can get so close, let's bring in gloeria borger. if any republicans doubt the inevitability, they will wake up tomorrow morning with not much of an answer. >> right. i think it won't be a surprise to wake up and say mitt romney did very well. he is the presumptive republican nominee, although newt gingrich doesn't like when we use that word. but also i think when we look at the results tonight, we can also see among republicans whether there still remains kind of a hard core, anti-romney constituency out there. let's see if he gets real super majorities out there, because that would be one way to say, okay, the party may indeed be starting to unite around mitt romney and look towards the general election. >> and the fact that he is in new hampshire. a small state when it comes to the electoral college, but i can give you a scenario in which a new hampshire or iowa or state of that size could decide the election. governor romney essentially trying to start again. to go back to the big first primary he won and frame the general election with a message of jobs, jobs, jobs, no more obama. >> we've been talking a lot about the pivot this week that. seems to be our favorite phrase. and, yes, he's pivoting. to the general election, to talking about women, for example, where he's not doing well, hispanic voters not doing well, young voters on the student loan issue today where romney is not doing well. so, you know, he is kind of moving to say, okay, these are where i need to shore up my support. we've also learned today that sometime in early may, mitt romney is going to meet with rick santorum. hopefully he can shore up his support within his own party and get the base enthusiastic. >> delicate balance. work on your right to shore up the issues while also trying to get a little more support in the center. >> and seeming authentic at the same time. right? >> if you don't think there's drama, it's very much worth listening to governor romney just because of the tone. gloria, thank you. in a moment we'll return to the breaking news and ask the agriculture secretary, tom vilsa vilsack, about the first case of mad cow disease in six years. later, a top republican senator unhappy with the investigation, declared white house aides of wrongdoing in that secret service sex scandal. 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you just have to eat it as part of your heart healthy diet. step 1. eat the soup. all those veggies and beans, that's what may help lower your cholesterol and -- well that's easy [ male announcer ] progresso. you gotta taste this soup. more now on a breaking public health story we told you about at the top of the hour. the u.s. agriculture department confirms a case of mad cow disease in central california, the first case here in the united states in six years. secretary of agriculture tom vilsack is with us exclusively. how did you find this cow? >> basically tests were run. we confirmed tests and this was a cow not going in the food system. we basically took it out of the food system and made sure that it was going to go to rendering. so very rare circumstance. i can assure you and everyone who's watching this tonight that our food supply is safe and will continue to be safe. >> now, people hear mad cow disease and get a bit of fear and justifiably so. this was one cow not going to be slaughtered for meat purposes, it's one. but if there's one, does that mean there's two or do you not know the answer to that? >> the reason i'm certain is we've taken steps since 2004 to ensure that the types of products from animals that could potentially be the cause of mad cow disease in humans are not in the food system to begin w we've taken out the brain, the spinal column. none of that goes into the food system, so i'm very, very confident that we have a very safe supply of food here in the united states. >> what do we know about how and where? >> california dairy operation. this is an atypical case, which means it's not connected in any way, shape or form to feed. we have a feed band, so that's reassuring. a very rare circumstance and situation. it can just sort of come up and pop up. sometimes it's genetic. but in any event this particular animal is contained and will be destroyed. >> help somebody watching who might not understand the science. this is a dairy cow so it was not in the meat supply. but if somebody out there says why, why should i trust you when you say the food supply, how do you know? how do you know? >> we know because of taking out of the feed and out of the food supply those parts of the animal that could potentially cause the mad cow disease in humans. it's taken out to begin with. it's not put into the slaughter process, it's taken out. the same thing is true with dairy products. we know that those are safe as well. people need to be reassured, john. every time i hear one of these stories, i obviously think of an american family sitting down and we want them to continue to be safe and secure about their food supply. i also think about the farm family who has to have the backing of the american public. they know their job and responsibility is to make sure the food is safe. >> as you know both from your current job and your prior job as a governor, when these things have come up in the past, sometimes our trading partners in the view of the united states and in the view of farmers have overreacted by putting bans on u.s. meat and the like. what communications are happening to make sure if you're right about this, that it's a small, isolated case, that there's not a panic in the market, if you will? >> first of all, this is only the fourth case reported worldwide and we've seen a substantial reduction in the number of cases. we've taken the steps of notifying our canadian and mexican partners in north america and also taken the step of looking at our top 20 trading partners and reassuring them that this is the way the system is supposed to work. we're supposed to identify the circumstances and make sure they don't get in the food supply. so our trading partners should be reassured. the domestic markets were reassured. the markets rebounded an i think we'll be in good shape tomorrow. >> was this cow tested as part of a government program or did the dairy operator say i think i have a problem? >> this cow probably evidenced indications or signs that gave people a sense of concern and the testing went into place. we routinely test throughout the country and the results obviously indicated the possibility. we then went through two confirmatory tests. we're also going to send the results to the international oie as part of our agreement with international processes to make sure that everybody understands it's a very transparent process and we're doing what we are supposed to do. >> but as we speak tonight, you are 100% certain, no threat to the food supply? >> i am going home and i am having beef for dinner and that's no lie. >> mr. secretary, i appreciate your time on this important day. thank you, sir. tomorrow brings another major showdown in the u.s. supreme court. we'll preview the fight over arizona's crackdown on illegal immigration. first, pictures you won't want to miss. a baby girl grows up right before your eyes. man: 1939 -- my parents ran across an ad for a hot dog cart. my mother said, "well, maybe we ought to buy this hot dog cart and set it up someplace." so my parents went to bank of america. they met with the branch manager and they said, "look, we've got this little hot dog cart, and it's on a really good corner. let's see if we can buy the property." and the branch manager said, "all right, i will take a chance with the two of you." and we've been loyal to bank of america for the last 71 years. let's start with car insurance x. this one does save people a lot of money and it's very affordable. it was very delicious. could you please taste car insurance y? this one is much more expensive. ugh. it's really bad. let's see what you picked. oh, geico! over their competitor. you are a magician right? no., oh. you're not?, no., oh, well, give it a shot. i am so, so sorry. it was this close. welcome back. here's kate bolduan with the latest news. we are following some news of a death just in from the kennedy space center. a custodian's body was found on a launch pad this afternoon. the man hasn't been identified. he was found near a liquid oxygen tank and paramedics were unable to revival him. no word yet on the cause of death, though. we'll be following up on that. and federal officials made their first arrest today in the 2010 gulf oil spill. former bp engineer kurt mix is accused of destroying evidence by deleting hundreds of text messages about how much oil was leaking into the gulf. some of those texts allegedly say more oil was leaking than bp had let on. mix is facing up to 20 years in prison if convicted on two counts of obstruction of justice. apple products rarely disappoint and neither do their earnings reports. the company's profits nearly doubled to almost $12 billion, more than exceeding wall street expectations. apple also reports $39 billion in sales, up 60% from last year. pretty impressive. better hold on to that stock, though. it climbed 6% in the first minutes after the news broke. some good advice for you there. and they grow up too fast, some parents say. in one father's case, it only took about three minutes. take a look at this video. the dutch filmmaker compiled video of his daughter over the past 12 years of her life. we sped it up even a little more to get it in. he posted the 2 minute, 45 second video and it's already gotten three million views. it fittingly ends with the caption "to be continued." that's a really amazing thing. >> it's really fun but trust me, as the parent of a teenage daughter, the to be continued part will be harder. daddy, no. daddy, no. not that, daddy, no. no, daddy. >> i don't like that picture. yeah. at least for the first 12 years it was fun. >> that is fun. a lot of parents are going to think i'm going to try that. >> it's a really fun idea. >> there will be a caught of copy cats to that. >> copy away. nine of the 12 secret service members implicated in the sex scandal being forced out of the agency. coming up, a senator that's not happy with a separate investigation that found no wrongdoing by white house aides. plus explosive allegations. the new orleans saints bugged the opponents' locker room. what happens when classroom teachers get the training... ...and support they need? 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