Two separate incidents on board two Royal Caribbean cruises led to more than 500 passengers falling sick, with five of them having to be hospitalized in one of the cases. The incidents took place in the Royal Caribbean International-owned luxury cruises Ovation of the Seas and Independence of the Seas, in November and December, respectively. 

Royal Caribbean Cruises Ltd, the parent of Royal Caribbean International, is a well-known global vacation company offering luxury travel from Europe, Asia, Oceania, the Pacific North-West and the Caribbean.

According to its website, its three major cruise brands — Royal Caribbean International, Celebrity Cruises and Azamara Club Cruises — operate a total of 49 ships to 535 destinations across the seven continents. The ships have a total passenger capacity of 92,000 and employ more than 60,000 employees, Cruise Deals reported. 

“At Royal Caribbean Cruises Ltd., excellence, innovation, and imagination reign supreme. It’s evident in the way our ships are designed, and in how we deliver world-class hospitality at sea," its website claimed. 

The Royal Caribbean International was launched by the company in 1969. According to its website, the cruise line was one of the first in the industry to offer its passengers adventure sports such as rock climbing, ice skating and surfing at sea.

The outbreak of illness in the cruises happened when 332 of the 5,547 guests aboard the Independence of the Seas complained of gastrointestinal illness after the cruise departed from Port Everglades in Florida on Dec. 11. A similar case was reported on the Ovation of the Seas last month after it departed from Singapore on Nov. 23, with 5,796 passengers. Two hundred and nine of them reportedly showed symptoms of stomach-related sickness.

Dr. Mark Veitch, director of public health at Royal Hobart Hospital, where five passengers aboard the Ovation of the Seas received treatment, said in a statement it was uncommon to see these types of outbreaks and requests for medical assistance for passengers in big cruises.

But such outbreaks are not entirely unheard of.  According to Centers for Disease Control database, a case of norovirus was recorded on the Anthem of the Seas — another Royal Caribbean cruise — in February 2016.

Dr Veitch said the cruises followed established protocols to manage the outbreaks and limit their spread. It was not immediately clear whether any of the passengers aboard the Independence of the Seas was hospitalized.

"Those affected by the short-lived illness were treated by our ship's doctors with over-the-counter medication," Cynthia Martinez, a Royal Caribbean International cruise line spokeswoman, said about the Ovation of the Seas outbreak, NBC reported.

The husband of one of the passengers admitted to the intensive care unit at the Hobart hospital said his wife consumed “uncooked chicken” on the cruise, which caused her health to deteriorate.

"Her condition continued to worsen and I thought she was going to die in front of me," he added, while speaking to the Associated Press on the condition of anonymity, due to privacy concerns.

The company, based in Miami, is listed on the New York Stock Exchange. The stock closed at $125.09 on Dec. 15, up by $3.40. Its stockholders include Caxton Associates LP, OxFORD Asset Management LLP, Axa and California Public Employees Retirement System.

Royal Caribbean Cruises generated revenues of an estimated $8.5 billion in 2016, a 2.4 percent jump since 2015. It also saw a significant spike in its profits in 2016 — generating a net profit of $1.28 billion, or $5.93 a share, as compared to $665.8 million, or $3.02 a share in 2015, the Sun-Sentinel reported.