A Belgian triathlete who fell ill, causing her team to withdraw from a mixed relay event at the Paris Olympics, said blood tests showed it was a virus that made her sick. Belgium’s Olympic committee announced on Sunday that it would withdraw from Monday’s triathlon mixed relay because Claire Michel was unable to compete.

Michel had competed a few days earlier in the women’s triathlon, which included a swim in the Seine River. Some news outlets had reported that Michel had been sickened by E coli and spent several days in the hospital.