A brilliant marine biologist has told how she woke up an "entirely different person" with no memory of her previous life because of a rare condition that causes the body to attack its own brain cells.

Fran Geall, 25, from Falmouth, Cornwall, who has a masters degree, was struck down with the auto-immune condition encephalitis, which wiped all recollection of her £50,000 (approx. $66,000) five- year university education.

As well as forgetting her time in academia, Geall said she no longer knew some of her closest relatives and friends - including her niece and her partner's family, explaining: "With people I'm told I've known for years, it can be like meeting them for the first time, which is really sad. I also feel like I'm meeting myself again, because I have absolutely no idea who I was before all this was."

"People say there's a new Fran, that I'm a different person and they're having to accept that. I'm not so sure if I like the new Fran, though," she said. "All I want is to get back to the old me, who achieved so much and built so many loving relationships."

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As "old Fran," she completed an undergraduate degree in marine biology, before being awarded a Master of Science in sustainable agriculture from Plymouth University.

Keen to work in ethical agriculture in January 2018 she landed her "dream job" working as a business development manager for an oyster company in Whitstable, Kent.

In December 2015 she had also become engaged to marry the love of her life, teacher Stacey Tonkins, 29, who she had met at university in 2014.

But her happiness was shattered in March this year when she began suffering from migraines so crippling that she was forced to stay in bed for a week.

She saw her doctor and once visited the emergency room, but doctors thought she had pulled a muscle in her neck, as she could not put her chin to her chest.

Geall was struck down with encephalitis – a potentially deadly condition that causes swelling on the brain. (PA Real Life)

Then, one morning in March, she began having a seizure in bed and it became clear something was very wrong - prompting Tonkins to call an ambulance to rush her straight to Kent's Ashford Hospital, where she was immediately put into an induced coma.

Coming to a week later, she seemed like a completely different person.

Unable to read, walk or speak for several weeks, she is still having to relearn many basic life skills.

"Doing the simplest things, like using a computer or navigating around a supermarket have now become very difficult," said Geall. "But what is heartbreaking for me is that my intellect, which was like my superpower, is now gone, and all the years I spent learning facts and learning about the natural world has been wiped out like chalk on a blackboard."

Despite having scant memories of her life before her brain condition, fortunately, Geall said she still feels an instinctive emotional link to many of her loved ones, such as Tonkins her parents and her siblings.

But she has no recollection at all of her sisters-in-law or her niece and is now having to rebuild these relationships from scratch.

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"When Stacey and my family visited me in hospital, I knew instinctively that they were people I loved, but I couldn't remember anything about them, apart from very minimal, basic details," she said. "They would show me photos of old times together and it wouldn't jog anything - it's like looking at someone else's life. I couldn't speak, I couldn't walk and I had no idea who anyone around me was or what had happened to me."

Slowly, her faculties began to return, although Geall could write before she could talk.

"I don't know why, but the first thing I was able to write down was my mum's telephone number. I couldn't remember anything, but for some reason, I could remember that," she said. "The second thing I wrote was, 'things are a jumble.' My friends and family tried to communicate by speaking and writing things down, too, but I couldn't understand anything."

Things gradually improved when Geall was given a plasma exchange 10 days after being admitted to the hospital, a procedure which replaced the white blood cells in her system that had been attacking her brain.

After that, her speech recovered and she started writing a daily diary although, sadly, it did not trigger any memories.

Discharged from hospital after five weeks, determined to get back to normal, she returned to work.

Within a few days, however, it became clear it was not going to be possible for her to stay when she had a major seizure.

"I realized then that my recovery would take a lot longer than I had imagined," she explained. "The doctors have no idea if I will ever regain my memories, so I'm living with the prospect of potentially having to relearn everything I ever knew."

Now based in Falmouth, near Geall's family, who are helping to support her and her fiance, the marine biologist - who once spent a few years studying in the seaside town - is putting all her energy into her recovery

"When I'm out people will sometimes come up to me and say hello, as they recognize me from when I lived here before," she said. "Obviously, they don't know what I've been through. I have no idea who they are, but still smile and pretend to know them. We only have a brief conversation, so they're usually none the wiser. If I talk to anyone for longer, they can usually tell something isn't quite right, so I tell them what happened."

Luckily, Geall has not lost her hunger for knowledge and is now reading up on everything she learned at university, keen to retain it - although she can only study for short periods, as the mental exertion can trigger seizures.

As doctors have no idea what caused her encephalitis, a condition which still frequently baffles the medical profession, Geall often blames herself for what has happened.

"In a way, I feel like it's my fault," she said. "There's no logic to that whatsoever, but if I tell myself that it's just unfair, it puts me into a spiral of depression. Telling myself that there was some reason behind it lets me think that I can somehow get better and move on, even though no one seems to know if I'll ever have my memory back."

Although the future remains uncertain, Geall is delighted when people tell her they still see signs of the person she used to be.

"People say that I used to crack a lot of jokes, and I'm starting to do that again now," she said. "But I suppose when you're in a situation like mine, what else can you do?"