U.S. swim star Katie Ledecky on mystery illness: “I’m not lying when I say I almost got out at the 1,100 mark.”

STANFORD — Swimming superstar Katie Ledecky says she got so sick at the World Championships last month in South Korea that she almost quit in the middle of a race.

That would have been a first.

“I’m not lying when I say I almost got out at the 1,100 mark,” said Ledecky, who was swimming the 1,500-meter freestyle, a new event for the Olympic Games next summer in Tokyo. “I’ve never felt like that before in the 1,500. I’ve had a lot of 1,500s that have hurt and I put myself through a lot in some of those races, but never have I gotten to the point where I felt I was going to have to get out.”

Ledecky finished that race, but withdrew from the 1,500 final and also withdrew from the 200 freestyle preliminaries. Despite the stomach virus she’d contracted, she still came home from Gwangju, South Korea with three medals.

Ledecky, 22, recounted the ordeal this weekend during the Phillips 66 national championships being held in her home pool at Stanford University. Taking a two-week break from competition, she attended as a spectator.

A five-time Olympic gold-medal winner with world records in the 400, 800 and 1,500 freestyle events, Ledecky still isn’t sure what happened to her in South Korea. She said she didn’t feel well at the start of the meet. Her symptoms included weight-loss, headaches, an elevated heart rate and sleeplessness.

After fighting to finish the 1,500 prelim, she requested medical care. She sat in ice packs for almost 30 minutes to decrease her body temperature. Ledecky said she has undergone medical tests in the Bay Area to ensure she is OK.

South Korean organizers housed the swimmers in a village as host cities do during the Olympics. That meant athletes from around the world ate in the same dining halls. Ledecky said she used hand sanitizer offered in the cafeteria before eating.

“But I can’t control if there is something in the food if the food wasn’t being cooked properly,” she said. “I couldn’t control if other people were (not) using the hand sanitizer. I couldn’t control whether people were grabbing the dinner rolls with their hands and infecting things.”

Despite lingering effects of the illness, Ledecky returned to competition to help the United States finish second in the 800-meter freestyle relay. She said she still didn’t feel well when racing in the 800 freestyle last Sunday.

Ledecky suffered from nausea just before climbing onto the starting blocks. Then she found herself in a duel with Italy’s Simona Quadarella, who took the lead in the second half of the race. But Ledecky out-sprinted Quadarella in the final half lap to win her only world title of the meet.

“It was a race that was different from any other race I’ve probably ever swum where I did kind of have to assess how I was feeling and adjust on the fly,” she said. “It was good racing. That’s what it was – it was racing. I didn’t care about time at that point.”

Ledecky often is so far ahead of competitors in the distance events that time becomes the focus. The question often is whether Ledecky will shatter her world record.

She won four gold medals at the 2013 World Championships a year after winning the 800 freestyle at the London Games at age 15.

Then Ledecky took over women’s swimming. At the 2015 World Championships, she won every freestyle event from the 200 meters to 1,500 meters while also setting two world records. Ledecky won four gold medals and one silver medal at the Rio Games in ‘16.

The plan is to add to the medal haul with the addition of the 1,500-meters event in Tokyo.

But Ledecky has been careful about using the virus as an excuse for failing to win the 400 meters freestyle in South Korea. Ariarne Titmus, 18, of Australia, won the event with Ledecky finishing second.

Ledecky said her competitors are catching up to her, regardless of her health. But the swimmer also felt confident about her training at Stanford heading into the World Championships. She said it was as good as it ever had been.

“That should have shown in Gwangju,” Ledecky said. “It’s not like that training goes away.”

In other words, wait until next year.