The San Diego cruise port has confirmed to 10news that some passengers onboard Azamara Quest were sick with the virus.
The vessel, owned by Royal Caribbean, is on its last stretch of a 14-day one-way voyage from Costa Rica to San Diego.
Currently, there are more than 1,000 people onboard including passengers and crew. In the tight quarters the illness may spread fast.
Azamara Quest carries up to 408 crew and 781 passengers, meaning a lot of people are exposed.
It is still unclear how the outbreak started and how many people are sick.
For other Azamara Quest accidents and incidents see at the ship's CruiseMinus page.