this is "nightline." >> tonight, medical miracle. the teenager from florida and the lethal brain-eating parasite that lurks in some lakes and water parks. the doctors turned detectives, the rescue. the bug that kills 90% of its victims. ? she was the woman behind the words of quhufwhitney houston's classic "i have nothing." that hardly describes her life. from early marriage to elvis, bruce jen exert secret he shared with her. >> he said, i am a woman. i would like to become female on the exterior. >> it's all in her memoir "a

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we start here tonight with what doctors are calling a medical miracle. sit a by turns horrifying and moving story that involves a 16-year-old boy infected with a rare brain-eating parasite. his doctor told the parents to say their final good-byes. but then a desperate phone call and a frantic 30-minute drive in pajamas may have saved the day. it's the classic stuff of summer. kids cooling off i lakes, streams. but beneath the surface of these idyllic scenes there can be something genuinely terrifying. a common parasite that's been called a brain-eating amoeba. infection is rare but 97% of people who get it die. >> he's currently walking, talking. it's a miracle. >> reporter: 16-year-old sebastian de leon beat the incredibly bad odds and survived.

this medical team and this hospital for having our son back. >> reporter: a few days after swimming in a body of water on a private property in southern florida, sebastian was rushed to the hospital on august 7th with an excruciating headache, squeeze queasy, sensitivity to light. doctors at florida hospital for children at first thought his symptoms looked like meningitis but tests revealed something much worse, a >> the family immediately within four hours i had to tell them to say their good-byes. i had to tell them, tell him everything you want to tell your child, because i don't know from the time i put him to sleep to the time i take the tube out will he wake up. >> reporter: doctors made a crucial phone call to father-son team todd and michael mclaughlin, who distribute a life-saving druggiveavido.

it to the hospital right away. >> reporter: michael was less than 30 minutes away from the hospital. >> my mind went into one fear. because i know how deadly the amoeba is. then excitement. i think my adrenaline just went pumping from there. i'd already picked up the keys, was in my car. >> reporter: he jumped into his car in pajamas, no time to waste, because the parasite eats away at the brain so quickly. >> by the time i dropped it off, it was just relief. i knew that this would definitely bene quickest times they'd received the drug. >> reporter: doctors administered the drug and then watched and waited as sebastian lay in a medically induced coma for three days. >> we woke him up. and we decided to take the breathing tube out. and within hours he spoke. >> reporter: the vast majority of people who get infected with this amoeba are not so fortunate. >> ponds are host to a deadly amoeba that claimed the life of

>> -- whose daughter was dead the minute she jumped in the water, she just didn't know it. >> looking into a deadly amoeba infection. >> reporter: out of the 138 known cases in the u.s. in the last 50 years or so, sebastian is only the fourth survivor. the third, kalie hardic. like sebastian, kalie's troubles began with a seemingly low-risk summer outing to a water park. >> they had swings in the water you could swing on. they had like this jungle gym thing. these square blocks you can jump around on them. >> reporter: a few days later kalie came down with headaches, vomiting, and a fever. >> all of a sudden the headache just started getting worse. >> reporter: when her eyes rolled back into her head, kalie was rushed to arkansas children's hospital. doctors warned kalie's parents that she may only have a few days left. without a proven treatment course, they tried something

hoping to slow the parasite which thrives in high temperatures, and they gave her a cocktail of drugs including impavido, similar to what ended up saving sebastian. a month later she was out of the coma with a long road ahead of her. with therapy she was able to relearn basic skills. she began to walk and talk, saying hello to her mom again. >> when i was able to first say that first word, i was so excited. i was just happy. parasite researcher who's been studying this bug since the early '80s. he says the parasite enters through the nose, crosses the nasal lining into the sinuses, and finally invades the front brain where it starts eating away at the tissue. >> it could be from swimming, dunking your head, ingesting water into your nose. >> reporter: however, there is a lot that scientists do not know. for example, why some people get sick and others don't.

is it the person's immune system? there's nothing that really ties a string between getting infected and not getting infected. >> reporter: one of the reasons why so many people do not survive this infection is because they are misdiagnosed and they simply run out of time. which is what happened with 11-year-old jordan snellski. >> he loved to make you laugh and smile. he had the most amazing smile. >> reporter: his parents, steve and shelley, say their son contracted this deadly parasite while staying at a five-star re >> by did horseback riding, zip lining. the next to last day, we swam in one of the pools at the resort. and the pool had water slides. and it was warm water. it was hot springwater. >> reporter: the next day jordan got a headache, then spiked a fever and started vomiting. he was diagnosed with meningitis and given antibiotics. >> he started having hallucinations. >> he didn't know who he was.

then he had a seizure. they brought in the icu team. they moved him downstairs. he never regained consciousness. they did some surgery. that's when they detected in a sample the amoeba. >> reporter: finally, the correct diagnosis. but it came too late. >> he died wednesday morning at 6:30 a.m., six days and 12 hours after swimming. >> today the snellskis are turning their own pain into awareness for other families. they've started a foundation in honor of their son with the hopes o and doctors about the disease. >> our fear is there may be more cases out there that are misdiagnosed or diagnosed as something else. >> the signs of this infection are the same as for meningitis. so headache, maybe confusion, stiff neck. >> reporter: medical experts agree parents should take children to the doctor if they see these strange symptoms, but they emphasize this deadly infection is exceedingly rare. >> should we be thinking at all about prevention? >> i used to say, it's like

but getting struck by lightning is 10 times more common than getting this infection. >> so i shouldn't be worried about letting my kids swim in these bodies of water or swimming in one myself? >> you should worry. you should worry, do they know how to swim? you should worry about e. coli which is common. >> reporter: as for sebastian, the 16-year-old in florida, he's still in the hospital but doctors say he's making progress and his family is hoping for a adventurous, wonderful teen. and we are so thankful for the gift of life. next, what do elvis presley and caitlyn jenner have in common? you're about to meet her and hear the extraordinary story she has to tell. life lessons for out in the wild from a little seal that could. ? there's no one road out there. no one surface...

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there is a revealing new memoir out tonight from a woman with an epic love life. linda thompson walked down the aisle with bruce jenner back in the day. and that's just part of her story. here's abc's chris connelly. >> ladies and gentlemen, elvis presley and bruce jenner have left the building. >> reporter: ah, but she's here. linda thompson. chronicling with empathy and deep feeling days with elvis presley and the person we now know as caitlyn jenner. >> i think more than anything

to be able to emerge as her true self. for the rest of us we love her, we honor her, we respect her. but when i first met her, she was in a bruce jenner body. he was just an incredible person. still is. >> reporter: wed in '81. by 1985, they were raising sons brandon and brody here in malibu. you say this was the happiest time of your life? >> the very happiest time of my life. my happiness was complete. until that day when my remarkable husband came to me one day and said, i need t >> reporter: linda feared it was an affair. it proved more consequential than that. >> he said, i identify as a woman. it was effort-shattering. it was devastating. people can't understand. you must have had some kind of idea. no, naud da, never, nothing. >> reporter: they had proclaimed the joys of their union to the world at large. at first linda says she couldn't help but cry out in shock and anguish. >> i said, have you look in the

because you're not only a man, you're the epitome of the ideal man. because in my ignorance and in my naivete, i thought maybe this is something we could fix. to say that i was a blithering, pathetic idiot at the time would not be an overstatement. >> reporter: they separated and would divorce. jenner began hormone and hair removal treatments. one day the boys came home from a visit to their father's house. >> mommy, we saw daddy get out of the shower and daddy has boobs. my heart stopped for a minute. and i said, well, daddy hasn't been working out as much as he used to. when you stop working out and you've developed a big muscle, muscles become flabby, so that's probably what you saw. >> reporter: later linda would wish jenner all the best with marriage to kris kardashian. >> i was so elated that bruce was going to be happy. i moved on with my life. >> reporter: yet linda says her sons felt neglected by their father, whom she says for years was not a presence in the lives

through what kind of turmoil you are experiencing in your life, if you have a child, be a parent. you know? so there's really no excuse for that. but it's still forgivable. >> reporter: jenner's rep told abc news caitlyn was unavailable for comment. >> i was there for the first gig. >> reporter: yet all of it possibly the backdrop for this exchange with brody, a reality star via "the hills" from "keeping up with the kardashians." >> it's interesting to watch how you are with the >> yeah. well. >> because it's something i'm not really used to. you weren't around. i was a kid. >> now's not the time to talk about it. >> reporter: it was 2012, linda writes, when she told brandon, who told brody, about their father's gender dysphoria. after so many years of silence. >> they have since said, mom, thank you for not telling us. because i think we needed time and experience and life to understand different circumstances.

vividly captured by linda in "a little thing called life." in her glowing youth, linda thompson was a college senior and pageant standout in memphis. where in 1972 she met elvis, then 37, at a movie theater. and you can't remember the movie? >> no, would you be able to if elvis presley were sitting next to you? >> reporter: right there as the film screened things progressed at the rapid rate in the elvis love with you." ? but i can't help falling in love with you ? >> if you want to know what it was like to kiss elvis presley, just take two big fluffy marshmallows out and with the sweetness and the softness, kiss those marshmallows. he had marshmallow lips. >> reporter: moving into graceland, linda was by his side

when the king of rock 'n' roll turned 40, he didn't like the view. >> he started to do what we all do when we're standing in front of a mirror. what if i just -- what about this? i said, honey, you're fine, you're gorgeous, are you kidding? but he would not be satisfied until he had talked someone into giving him a facelift. >> reporter: 24/7, 365, linda was elvis' lover, confidant, confessor, and his caregiver. >> he admit this once, but i have a self-destructive streak. it was evident in a lot of things that he did. but particularly in the way that he abused his body with prescription medication. >> reporter: it would all end sadly in san francisco during november 1976. his drug-induced spiral compounded by infidelities that he would not own up to. >> and he would get tears in his eyes and grit his teeth. i love you!

about anybody else that i'm with, just know, they don't mean anything, i love you, i don't love anybody else, you're my girl. >> reporter: the love poems she'd write for elvis' eyes only leading her two decades later to a successful career as a song lyricist. part of the inspiration for this oscar-nominated song from "the bodyguard." ? stay in my arms ? >> i drew upon my experience with elvis, who was the male diva of all-time, and thus the line "stay in my arms if you dare." because there's a challenge there. when you're with someone who is that famous. and i never knew love like i've known it with you, which i certainly had not known love like i knew it with elvis, before or since. >> reporter: now 66, still in her malibu home, linda finds the loves of her past still reverberating in her day to day. >> caitlyn and i have talked about had she revealed herself

surrounding the issue today. there would not have been the understanding and the tolerance. caitlyn is trying to do as much as she can to open people's eyes. her heart's in the right place. i have since said to her, you know, you've got to give yourself credit, you kicked manhood's butt. >> reporter: for "nightline," i'm chris connelly in malibu, california. up next, one little seal displaying life-saving ingenuity in the face of killer whales. at the the lincoln summer invitation sales event it's time to relax. from the moment you take your foot off the brake, the brake stays engaged and you stay put. taking the legwork out of stop and go traffic. and even hills. that's the more human side of engineering. hurry in for limited time offers during the final days of the lincoln summer invitation sales event.

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finally, the little seal who has quite justifiably i would say gone massively viral. >> the seal's right there. >> you br to witness a very close call for one very lucky seal. >> all right, come on. fatso, stay there. >> watch as this seemingly hungry pod of orcas surrounds a

a sudden a atlantic seal pulls himself out of the water. scrambling to safety. >> here's in the boat! >> the seal waits it out on deck until the orcas apparently lose interest. >> that guy deserves to live. come on. just stay there for a sec. >> he then returns to the sea, leaving behind a lesson for all of us in wily resilience. >> well done, bud, survive! >> thank you for watching "nightline" tonight. "gma" first thing in the morni and on our "nightline" facebook page. thanks again for watching, good

? it seems today that all you see ? ? is violence in movies and sex on tv ? ? but where are those good old-fashioned values ? ? on which we used to rely? ? ? lucky there's a family guy ? ? lucky there's a man who positively can do ?