Stomach bugs, not hantavirus, are a bigger threat on cruises

• Gastrointestinal illness outbreaks on cruise ships reached a nearly two-decade high in 2025, with 23 incidents reported, though 2026 data shows a sharp drop.
• Beyond stomach bugs, a deadly hantavirus outbreak killed three people on a ship in April. Experts warn cruises carry higher infection risks.
• Despite rising illnesses, the cruise industry is booming post-Covid, reaching record 37 million passengers in 2025, with strong demand expected.

WASHINGTON – Stomach bugs on cruise ships recently hit a nearly two-decade high as more people than ever board the vessels, underscoring how easily viruses spread on contained voyages.

While cruises are in a global spotlight after a rare hantavirus outbreak killed three people on an ocean liner since April, mild gastrointestinal illnesses are far more common on ships.

They have risen for the last four years to the highest since 2007, according to data from the Centers for Disease Control and Prevention’s (CDC) Vessel Sanitation Program. The data tracks ships with 13 or more passengers with foreign itineraries that dock at one or more American ports.

The Vessel Sanitation Program tracks the number of gastrointestinal outbreaks that cruise ships report every year, defined as situations when more than 3 per cent of people on board have some kind of stomach illness.

A new variant of the stealthy norovirus in 2006 led to a sharp increase in outbreaks on ships. They subsequently declined, but the number of such outbreaks has risen since the pandemic period and reached 23 in 2025, the highest number since 2007, according to CDC data.

A new strain was associated with outbreaks on land in 2025, according to a CDC spokesman. January through mid-May 2025 saw the number of stomach flu outbreaks reach 17 on cruise ships, but that number has fallen to four in that same period in 2026, the spokesman said.

Hantavirus shock

Passengers and crew from the MV Hondius are returning home throughout the world after the deadly outbreak of the Andes strain of hantavirus spread on the ship in April.

The ship did not dock at a US port but has caught the attention of Americans, as well as travellers globally. The incident brought back memories of the cruise ship quarantined off the coast of Japan in 2020 during the Covid-19 pandemic.

Most cruises halted voyages during the height of the Covid-19 pandemic, but since then the industry has been booming. Global cruise passenger volume reached a record 37 million in 2025, with demand expected to persist into 2026, according to the Cruise Lines International Association.

Health concerns in the past have not dented demand, and advance bookings in 2026 at Carnival and Royal Caribbean Cruises are holding up, said Ms Jaime Katz, an analyst at Morningstar.

“There’s an initial hesitation on booking until consumers are able to distil the magnitude of the impact of that outbreak,” she said.

Carnival and Royal Caribbean did not respond to requests for comment. Norwegian Cruise Line Holdings referred questions to the Cruise Lines International Association.

Cruise ships operate under strict mandatory reporting that makes outbreaks more visible, and illness rates on-board remain below hospitality settings on land, the association said in a statement.

“If you’re going on a cruise, you need to recognise the risk is higher,” said Mr Abraar Karan, an instructor in the division of infectious diseases at Stanford University.

Dense socialising spaces, as well as shared food and water systems, can accelerate the spread of diseases, while limited medical equipment and staffing make curbing infections harder, he said.

The average cruise-goer also is older and may be more likely to pick up infections, said Mr Karan, who recommends wearing a mask on ships where respiratory illness is found and washing your hands.

“Cruises are a lot of fun,” he said. “But that’s just part of the trade-off.” BLOOMBERG