Norovirus linked to gastrointestinal illness outbreak on Viking Polaris cruise ship

CANADA – The Viking Polaris cruise ship completed its two-week voyage from Toronto to New York City on April 23, 2025, amid a norovirus outbreak that affected more than 30 individuals, including 28 passengers and 4 crew members. 

Predominantly characterized by vomiting and diarrhoea, the gastrointestinal illness was reported to the Centers for Disease Control and Prevention (CDC) Vessel Sanitation Program (VSP) on April 18, 2025, seven days after the cruise began.

VSP officials remotely monitored the situation, reviewing the ship’s outbreak response measures and sanitation procedures.

As part of the ship’s outbreak prevention and response efforts, Viking Expedition Operations and the crew increased cleaning and disinfection procedures.

They also collected stool specimens from gastrointestinal illness cases for testing, isolated ill passengers and crew, and consulted with VSP about sanitation procedures and illness reporting.

This outbreak marks the 13th gastrointestinal illness incident reported to the CDC from a cruise ship in 2025.

Ten out of the 12 previous outbreaks were confirmed to be caused by norovirus. The CDC’s VSP continues to support cruise ships in monitoring, preventing, and responding to such outbreaks.

Norovirus transmission risks on cruise ships and beyond

Traveling on cruise ships exposes people to new environments and high volumes of people, creating the risk for illness from contaminated food, or water or, more commonly, through person-to-person contact.

According to the CDC, Norovirus is the most frequent cause of outbreaks of diarrheal disease on cruise ships, at over 90%, but they account for only 1% of all reported norovirus outbreaks. 

When the ship docks, norovirus can be brought on board in contaminated food, water, or by passengers who were infected while ashore. 

Repeated outbreaks on consecutive cruises may also result from infected crew or environmental contamination, as norovirus can persist on surfaces for days or weeks, while being resistant to many common disinfectants.

In addition to posing a risk of continued transmission aboard the ship, infected individuals may also spread the virus to the general public after disembarking, particularly if they return home or travel while still contagious.

Norovirus at a glance

It is sometimes called the “stomach flu” or the “stomach bug” and causes acute gastroenteritis, an inflammation of the stomach or intestines. 

While there is no specific medicine to treat norovirus illness, most affected individuals are likely to recover within 1 to 3 days. However, they can continue to spread the virus for two weeks or more after recovering. Antibiotic drugs are not effective as they target bacteria, not viruses.

Norovirus symptoms typically appear 12 to 48 hours after exposure, with the most common being stomach ache, diarrhoea, vomiting and nausea, which may lead to dehydration. Other symptoms may include fever, headache, and body aches.

The virus spreads through direct contact with infected individuals, contaminated food, utensils or contaminated surfaces.

Sign up HERE to receive our email newsletters with the latest news and insights from Africa and around the world, and follow us on our WhatsApp channel for updates.