Is It Safe to Go on a Cruise This Summer?

People around the world have watched this month as the hantavirus outbreak on the cruise ship MV Hondius unfolds. And for good reason—it calls to mind the early days of the COVID-19 pandemic, when an outbreak on the Diamond Princess ship was an early harbinger of things to come. 

While this outbreak of hantavirus does not have the same pandemic potential, and risk to the public is very low, it does beg the question: Why do cruise ships seem especially vulnerable to disease outbreaks? 

“You can think of cruise ships as disease sensors,” says Ben Lopman, PhD, professor of epidemiology at Emory University’s Rollins School of Public Health. “They travel around the world and pick up the viruses that are transmitting on land, which can then be amplified on a cruise ship. They’re a reflection of what's going on in the outside world.”

Cruises Are the Perfect Environment for Disease Spread

Cruise ships, from their close quarters to their buffet dining, create an ideal environment for spreading diseases.

“On a cruise, you have hundreds or thousands of people in very close, confined spaces, with small cabins and lots of shared meals,” says Elizabeth Rogawski McQuade, PhD, associate professor of epidemiology at Rollins. “People come from all over the world, so it's just a big mixing pot where diseases from diverse places can be transmitted.”

The high level of interaction between people on a cruise makes infectious illnesses spread easily. Large groups of people breathing recirculated air, touching the same surfaces, and impeding their immune systems with alcohol makes them vulnerable.

One common cruise disease is norovirus, an extremely contagious virus often called the “stomach flu.” After exposure, people start to experience symptoms and expose others in as little as 12 hours. Even on short cruises, norovirus can spread quickly through the passengers.

Outbreaks of diseases like norovirus also seem so common on cruises because they are easier to detect than they are on land.

“People are on a cruise long enough for transmission to occur and then to recognize that the cases are linked,” says Lopman. “If those same cases had occurred on land, say at a restaurant where people were all exposed to the same contaminated food, they would all go off in different directions and most of the time we wouldn't even know there was an outbreak.”

Hantavirus Is Not a Typical Cruise Concern

Some may have concerns about cruising in the wake of the hantavirus outbreak. It is important to note that hantavirus is rare, usually not transmissible from person to person, and not typically found on cruise ships. 

The current outbreak of hantavirus was, however, recognized and contained thanks in large part to it happening on a cruise.
“Hantavirus has an extremely long incubation period, up to about six weeks,” says Lopman. “The reason that this outbreak was recognized as effectively as it was is because this was a long cruise. Someone got exposed, transmission occurred on board, and it was enough time to see the cases develop.”

Many sources say that hantavirus spread on this cruise due to “close contact.” That term usually means 15 minutes or more of close interaction with someone. During the COVID-19 pandemic, less than six feet was often cited as the distance for close contact.

Lopman warns against relying on the term close contact to guide our understanding of how hantavirus spreads.

“I think we should be careful until we have full data on understanding the transmission of hantavirus,” he says. “We have a lot to learn still. It's a rare virus, and only this one strain is transmitted person to person, but the limited evidence that we do have from an outbreak several years ago and what happened on the cruise ship now is that it seems transmission can occur through more casual contact. How frequent that is, I think that is still uncertain.”

How to Stay Healthy on a Cruise

Even though there is no need to panic about contracting hantavirus on your cruise this summer, there are still precautions everyone should take to avoid contracting norovirus, a cold, or other illnesses.

“The best prevention is hand hygiene,” says Rogawski McQuade. “That means washing your hands with soap and water whenever possible and, if there's not soap and water, using hand sanitizer. It could also mean potentially avoiding buffet items that seem to have been left out for a long time or using alternative dining options besides the buffet.”

“Do all the things you would normally do on land but maybe be a little extra cautious on a cruise ship,” says Lopman. “And if you have signs of respiratory illness, runny nose, cough, or sneezing, wear a mask or isolate to the extent possible.”