Paris, France - When Leanne Smith suffered a partially collapsed lung in June 2022, the idea of winning a Paralympics swimming gold medal, let alone returning to the pool one day, seemed impossible.

But on Tuesday, the 36-year-old American did just that.

Smith went one better than at the Tokyo Games three years ago to clinch the 100m freestyle S3, the category for swimmers without use of trunk or legs and partial functioning of their arms and hands.

"If you would have told me I would be a gold medalist in this race 18 months ago when I was just getting back into the water, I would have told you you were crazy," a grinning Smith told AFP.

"It's just another testament to the inner determination I have and people placing limitations and then me just saying, 'OK, well, just watch me, I'll make it back,'" she added.

Months before the setback of the vicious respiratory infection which led to her spending two months in hospital, Smith was on cloud nine having just claimed seven gold medals at the world championships in Portugal.

The success was just a decade after being diagnosed with dystonia, a progressive disease which affects all four of her limbs, her vocal cords and her trunk.

Smith's crowing moment, 11 years after starting the sport, came in front of thousands of fans at a packed La Defense Arena in Paris.

"It's kind of our redemption swim from the silver in Tokyo," Smith said. "It's definitely nice to have achieved that upgrade."

"We called it that (redemption) jokingly."

"And then as we started to see how pieces would fall as far as regarding the pretty major setback after Madeira in 2022, we didn't really know what life would be like... swimming wasn't even on the table after that day,” she added.

Smith is from Massachusetts, and a Paralympic Games on US home water in Los Angeles in four years' time remains an option.

"I haven't really thought about it too much,” Smith said.

"I know it's coming up but again, just making it here is such a huge accomplishment that I really just want to relish and take in the moments and the swims that I'm having here.

“It's not off the table," she said. "But at this time, we're just enjoying where we're at."

"Four years is a long way away, so maybe some time off where it's not in the hospital or in the swimming pool is my next step."

"I think that's a good way to go," she added.