When national swimmer Nicholas Mahabir experienced fatigue and body aches in June 2023, the teenager brushed it off as “training effect”.

But when he started having fainting spells, he realised that it was something more serious.

The breaststroke specialist, who has not competed in seven months, told The Straits Times in an exclusive interview that his ordeal did not show any signs of easing.

“It continued to get harder,” the 18-year-old said. “The hardest part is the brain fog (memory problems, lack of mental clarity and an inability to focus).

“It’s like you want to do something but your mind cannot will your body to move.

“I was not able to train and simple tasks, like getting out of bed, were a struggle. I slept 12 to 16 hours every day for a few months, but it felt like a lot less.

“I grew up a very active outdoor kid but now, just going for a short walk would end up, on a few occasions, with me blacking out fully.”

Blood tests in August confirmed that he contracted the Epstein-Barr virus, which has no cure. It caused him to develop mononucleosis, a viral infection.

While the symptoms like fever can be treated, they may still be felt even for months or years. The virus can become dormant in the body, but may reactivate.

High-profile athletes who have the virus and continued their playing careers include tennis legend Roger Federer and American football’s Samuel Darnold, but two-time French Open finalist Robin Soderling stopped playing tour-level tennis at 26 due to lingering mononucleosis.

Despite his discomfort, Mahabir still set national breaststroke records in the 100m (59.96sec) and 200m (2min 11.87sec) at the TYR Pro Championships in California in July, coming within half a second of the Olympic qualifying time of 59.49 for the shorter event.

However, after his last race in the 200m breaststroke final at the US junior national championships in California on Aug 3, his condition deteriorated.

He missed the World Aquatics Junior Swimming Championships in Israel the following month, as well as the Asian Games and the recent world championships.

With the Paris 2024 swimming qualification window closing on June 23, his attempt to make his Olympic debut remains a major doubt.

Mahabir does not spend much time with people outside his family and coach, and remains baffled as he does not know how he caught the virus.

The California-based swimmer, who has an American father and a Singaporean mother, said: “It’s a terrible feeling. I had sacrificed my whole year and gone harder than ever, and was training better than ever.

“The fact that I was feeling 60 per cent energy-wise before I went 59 and 2:11 (for the national records) tells me that I would have been way faster had my health been 100 per cent.”

No Singaporean has won a world juniors medal, and his personal best in the 100m breaststroke is faster than American teenager Joshua Chen’s 1:00.70 winning effort in 2023, while his 200m record is just 0.03sec off Hongkong swimmer Adam Mak’s gold-medal time.

“Seeing a time slower than my personal best win at the world juniors was really disappointing. Letting down my team was the worst part, and not getting to hear the national anthem in Israel got to me,” added Mahabir, who won three individual silver medals and two golds in the 4x100m medley for the men’s and mixed teams at the 2023 SEA Games in May.

Motivated by his Olympic dream, he returned to the pool for light sessions in November after feeling better.

But the comeback was shortlived as the symptoms came back the following month.

His father then engaged a specialist who speculated that Mahabir’s mononucleosis could have been triggered by another viral infection. They are waiting on further test results to see if there is any way to alleviate his condition.

While he is frustrated because the Olympics are fast approaching, he also felt the timeout has helped him become mentally stronger.

After overcoming negative thoughts, he has occupied himself by working with a sports psychologist and studying swim techniques.

If he does not make it to Paris 2024, he hopes to bounce back for the 2025 world championships on home soil and then the 2028 Los Angeles Olympics.

Mahabir said: “No one knows what the future holds. All I can do is look after me, my health, be mindful of my choices that support that, and work on the things I can that will have me ready to take on the training when I can return to it.”

Singapore Aquatics’ swimming technical director Sonya Porter was sympathetic towards Mahabir’s plight, adding that they are providing emotional support while staying in close communication with his family and coach Peter Linn.

Porter, who had been to the US to meet Mahabir and Linn to discuss ways to support the swimmer, said: “The plan will be to target 2025 to provide a longer run-up, allowing his health to stabilise without external pressure to get ready on a faster trajectory than he is physically ready to.

“The immediate goal is health. Once established, there is no ceiling for possibilities.”

This article was first published in The Straits Times. Permission required for reproduction.