Olympic Games triathlete Claire Michel from Belgium is being treated in hospital for the intestinal disease E.coli after swimming in the Seine, reports Aftonbladet.
Michel fell ill on Wednesday, the day after she participated in the individual triathlon event.
As a result, Belgium will not participate in Monday's mixed triathlon competition.
"The Belgian triathlon team is very upset because what everyone feared has now happened. The Belgian Olympic Committee has decided to withdraw after talks with the athletes and their team," writes the Belgian newspaper Standaard, according to Aftonbladet.
The French decision to hold the competition in the Seine has met with resistance. One of the critics is Swedish Tilda Månsson, who also swam in the Seine during the women's final in triathlon, where she finished 23rd.
You feel that it's not super quality. It's brown and it smells disgusting. We'll see if you get sick, said Tilda Månsson to TT after the race.