France's prime minister said the symptomatic person was among five French nationals flown home on Sunday from the ship, now moored off Tenerife in Spain.
The case emerged during the evacuation of passengers from the Atlantic cruise vessel after a hantavirus outbreak linked to multiple confirmed and suspected infections.
Earlier reports said the Andes strain was involved, with three deaths reported, and health authorities treating all passengers as high risk for 42 days of monitoring.
A rare virus that jumps between humans has escaped a cruise ship. What happens next?
With an 8-week incubation period, how can officials be certain the cruise ship virus is truly contained?
Why do experts call the hantavirus risk 'extremely low' when its fatality rate is 38%?