Only 10 outbreaks were recorded by the CDC in 2018, down from 11 in 2017 and 13 in 2016, according to data posted at the CDC's Vessel Sanitation Program website.
It's the second lowest number since 2001, with only 2013 and 2014 showing lower numbers, with 9 outbreaks recorded.
Most gastro outbreaks are caused by norovirus, a common stomach bug that is highly contagious with a short incubation period, causing diarrhea and vomiting that typically lasts one to three days.
It's usually brought on board cruise ships by passengers at embarkation, USA Today reports. Five out of 10 of the outbreaks recorded were caused by norovirus, while one outbreak on a Cunard Line ship was the result of E. coli bacteria. The cause of the other four outbreaks was unknown.
Cruise ships are required to report cases of gastrointestinal illness to the CDC if they approach a US port after visiting a foreign port. When the number of cases exceeds 3 per cent of the passengers and crew on board, it is considered an outbreak, which is posted publicly on the CDC's website.
The data only covers ships that touch US ports and contain 100 or more passengers.
Numbers of gastrointestinal illness outbreaks recorded by the CDC rose in the 2000s, with numbers over 20 for several years – with a peak of 37 outbreaks in 2006. This was blamed on a new strain of norovirus.
Following the increase in outbreaks, cruise ships stepped up sanitation efforts, encouraging passengers to wash their hands frequently and use sanitising gel, while also adopting rigourous cleaning regimes.
The Crystal Symphony cruise ship was one of the vessels which experienced an outbreak of gastrointestinal illness last year. Photo / 123RF
Crystal Cruises' Crystal Symphony, Regent Seven Seas Cruises' Seven Seas Mariner and Silversea Cruises' Silver Shadow were among the cruise ships that experienced gastro outbreaks in 2018, according to the CDC's data.
Holland America's Volendam and Zaandam ships also recorded outbreaks and vessels operated by Princess Cruises, Azamara Club Cruises and Celebrity Cruises were also on the list.
