More than 70 crew and passengers, mostly elderly, fell ill late Saturday as the cruise organized by a Swiss company headed for Breisach on the German river bank from Strasbourg.
Six of the more than 200 people on board were taken to hospital in Strasbourg.
According to France Bleu Alsace radio, quoting German river police, they were discharged on Sunday.
The cruise continued Sunday but nine other people were hospitalized when it reached Breisach, police said in a statement.
Police suspected a virus or food poisoning to have caused the incident.