James Michael, 32, contracted schistosomiasis - also known as bilharzia - during his dream Africa trip.
James, who lives in Kensington in London, said: "When I look back at photos from my time in Africa, it's weird to think that's where the parasite crawled up my penis.
"It wasn't exactly how I imagined the trip of a lifetime to go...the whole experience was surreal and strange."
The 32-year-old had visited Africa with three friends in August 2017. They traveled from Zambia to Zimbabwe before visiting Malawi for five days.
The group swam and canoed every day on Lake Malawi, before flying back to the UK.
It was back in England that James' nightmare began.
In October last year, he started to notice a loss of feeling in both his legs - but initially put that down to fatigue from cycling.
But he checked himself into hospital when basic tasks like climbing the stairs to his flat became exhausting.
James was given antibiotics and sent home but, a week later, he felt even worse and so returned to Chelsea and Westminster Hospital.
"I explained to them that something serious was going on"
He said: "I explained to them that something serious was going on.
"I went to the neurology department and they did blood tests to see what was up. They determined quite quickly that my immune system was attacking my spine, leading to the loss of control of my legs.
"I was put on a six-month course of steroids to counter this...but they didn't actually know what had caused this."
Doctors from the Hospital for Tropical Diseases eventually told James a parasitic worm had crawled up his penis and laid eggs in his body.
A week before Christmas he was diagnosed with schistosomiasis, an infection that's caused by a parasitic worm that lives in fresh water in tropical regions. It's most commonly found throughout Africa.
Once in the body, the worms move through the blood to areas such as the liver and bowel. After a few weeks, they start to lay eggs.
Some eggs remain inside the body and are attacked by the immune system. If it's left untreated it could have severe consequences.
James was prescribed a medication called praziquantel that kills the worms.
He said: "That killed the infection but I was left basically debilitated. They told me there was a 30 percent chance I'd make a full recovery - 10 years from now.
"It was a horrible feeling - I felt completely helpless, and the odds weren't good. I couldn't wish what I've been through on anybody."
James spent a total of three months in the hospital using a wheelchair and then four months on crutches - until April this year.
He also had a breakout of extreme acne on his back and arms caused by steroids, as well as diarrhea.
He said: "The pain has been like nothing I've ever known.
"Early in my recovery, sometime in January, I had a really terrible acne outbreak that went all down my back and down my arms.
"I couldn't sleep for a month because lying on my back hurt. I couldn't really be under running water either, so I had to shower my front instead.
"The loss of feeling and use of my legs affected every part of my life. I wasn't able to exercise much because of the infection, which was hard.
This story was originally published by The Sun.