Gastrointestinal illness sickened more than 130 cruise ship passengers aboard a Royal Caribbean cruise earlier this month. The cause of the outbreak has not been determined.

An investigation has been launched after more than 140 people were hit with symptoms of illness while on board a Royal Caribbean ship. The US CDC is looking into what happened after passengers started showing signs of acute gastroenteritis (AGE), which is usually caused by norovirus.

The mystery gastrointestinal illness broke out onboard the Navigator of the Seas, a Royal Caribbean ship, on a round-trip to from the US to Mexico. Some 134 of the 3,914 guests fell ill, along with 11 crew members. Symptoms included sickness, abdominal cramps and diarrhoea.