Around 140 people have fallen sick with a gastrointestinal illness onboard the Cunard Queen Victoria cruise ship that docked in Fort Lauderdale, Florida, on Jan. 22 when the CDC began monitoring the outbreak.
According to the U.S. Centers for Disease Control and Prevention, 123 passengers and 16 crew members have reported being ill during a three-week leg of the voyage as of Thursday. Around 1,800 passengers and 960 crew members are onboard the ship in total.
The predominant symptoms of the gastrointestinal illness include diarrhea and vomiting. The cause of the outbreak remains unknown, according to the CDC.
The Queen Victoria is on a 107-night world voyage. The cruise ship is scheduled to stop in San Francisco on Feb. 6 and Honolulu on Feb. 12 before sailing to countries in Oceania, according to the Cunard website.
In response to the outbreak, the Queen Victoria crew has reportedly "increased cleaning and disinfection procedures" and "isolated ill passengers and crew."
"Cunard confirms that a small number of guests had reported symptoms of gastrointestinal illness on board Queen Victoria, Cunard Cruise Line told NBC News in a statement.
"They immediately activated their enhanced health and safety protocols to ensure the well-being of all guests and crew on board. Measures have been effective,” Cunard added.
The CDC's Vessel Sanitation Program continues to remotely monitor the situation, including "reviewing the ship's outbreak response and sanitation procedures."
Medical staff on cruise ships under U.S. jurisdiction are required to report gastrointestinal illness cases to the Vessel Sanitation Program when at least two percent of people onboard are infected.