The last thing anyone wants on holiday is a stomach virus: having to spend their days off huddled above a toilet.
But a food safety expert told DailyMail.com this could be the reality for hundreds of people getting away on cruise ships.
Dr. Darin Detwiler, a leading food safety expert in the US, told DailyMail.com that viruses such as E.coli, salmonella and norovirus are common on cruise ships due to the cramped quarters, the thousands of people on board and the large amount of communal food.
The highly contagious infections are spread through contaminated food, water or improper food handling and cause abdominal cramps, vomiting, diarrhea, fever, chills and fatigue.
In severe cases, sick people may become dehydrated or develop organ failure and require hospitalization.
Dr. Darin Detwiler, a leading US food safety expert, told DailyMail.com that norovirus is the most common stomach illness on the high seas.
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The CDC’s Vessel Sanitation Program (VSP) tracks and inspects outbreaks of gastrointestinal illness on cruise ships, and in 2024 the agency has recorded 10 incidents involving 1,040 passengers.
Of these outbreaks, seven were caused by norovirus, while three were caused by salmonella or E. Coli.
These viruses are usually caused by ingesting water or food contaminated with feces, or by consuming undercooked food, such as meat, eggs, or fish. The viruses can then spread when someone comes into contact with an infected person or a surface that a sick person has touched.
Overall, the CDC estimates that between two and four percent of cruise passengers experience these diseases each year.
And with an estimated 31.7 million people sailing worldwide, more than 500,000 people could become ill.
Cruise ships face “unique challenges” when it comes to food safety, Dr. Detwiler notes, “particularly because they serve large numbers of passengers in enclosed spaces where diseases can spread quickly.” They’re like floating cities.’
He added: “Cruise ships also typically source food internationally and stop at various ports to replenish supplies. This can result in varying safety standards, especially when it comes to fresh produce, meat and seafood.”
While most gastrointestinal diseases cause mild symptoms, vulnerable populations – such as young children, the elderly and pregnant women – may experience more serious complications, such as severe dehydration, organ failure, “or in extreme cases, death.”
To reduce the risk of illness at sea, the university professor shared his seven safety measures on this website.
WASH HANDS OFTEN, THE OLD FASHIONED WAY
The most effective way to prevent infections on cruise ships, Dr. Detwiler said, is to regularly wash your hands with soap and water for 20 seconds, or the length of two happy birthday songs.
He noted that this is especially important to do before meals.
While alcohol-based hand sanitizers are “helpful,” they “may be less effective against norovirus, so prioritize hand washing.”
In an effort to get young children into the habit of washing their hands, Dr. Detwiler recommended educating them about stomach flu and the possibility of getting sick.
AVOID THE BUFFET AT PEAK TIMES
Dr. Detwiler recommends dining during off-peak hours, when food turnover at the buffet is higher, or opting for made-to-order items
Buffets are known to be a source of contamination, especially if food is left outside for a long time.
To minimize risk, Dr. Detwiler recommends dining outside of peak hours, “when food turnover is higher, or opting for made-to-order items.”
During peak times there is a greater risk of contamination as people crowd around the food stations.
The CDC emphasizes that hot foods should be “steaming,” while cold foods should be visibly chilled.
The agency said, “Germs that cause food poisoning grow rapidly when food is in the danger zone, between 40 degrees Fahrenheit and 140 degrees Fahrenheit.”
These temperatures allow bacteria to multiply more quickly, with norovirus and E. Coli germs flourishing.
Norovirus is the most common type of stomach flu and usually occurs when a sick person touches food before it is served. However, foods such as fish and seafood can be naturally contaminated with it.
Although most people recover without complications, severe vomiting and diarrhea can lead to dehydration, requiring medical care.
E.coli is a bacteria that causes similar symptoms. It can also be found in raw and undercooked meat. Most strains are mild, but some can cause severe cramps and bloody diarrhea.
OBSERVE HOW THE FOOD IS PREPARED
When visiting buffet stations on the ship or other dining areas, Dr. Detwiler told DailyMail.com that it is important to watch how the food and drinks are prepared.
Some of his biggest pet peeves include servers not wearing gloves, unclean serving spoons, and food stored at the wrong temperature.
Meanwhile, in cruise ship bars, he said drink garnishes should be avoided.
A 2007 study published in the Journal of Environmental Health found that nearly 70 percent of lemon slices used as bar garnishes were contaminated with bacteria.
Dr. Detwiler says that if you notice unsanitary activity while boating, “it’s very important to speak up and say something.”
SKIP THE OYSTERS AND STEAK TARTARE
“Raw seafood and undercooked meats, such as steak tartare or ribeyes cooked rare, are more likely to carry pathogens,” says Dr. Detwiler.
Although raw bars, filled with everything from oysters to mussels, are considered an extravagant dining experience at sea, Dr. Detwiler recommends avoiding them.
In fact, he recommends skipping raw or undercooked foods altogether due to possible contamination.
He explained: ‘Raw seafood and undercooked meats, such as steak tartare or raw ribeyes, are more likely to carry pathogens. Even with runny eggs you run a risk.
‘Choose well-prepared dishes to reduce the chance of exposure to salmonella or listeria.’
People with salmonella develop stomach problems and fever, which can become severe and require hospitalization.
Many of these foods may also contain Listeria Usually found in unpasteurized milk, soft cheeses, prepared foods, fish, cured meats and pre-cut fruits.
Most people with listeria will not become seriously ill. But in some cases it can cause confusion and seizures, miscarriage in pregnant women, and even death.
STICK TO BOTTLED WATER AND BE AWARE OF ICE
Although cruise ships purify their water, Dr. Detwiler says bottled water is “a much safer option and worth paying a little extra for.”
This is because cruise ship water can be contaminated with enterotoxigenic Escherichia coli (ETEC), a type of E. coli bacteria that can cause diarrhea. It can also be the source of legionella, a bacterium that can cause Legionnaires’ disease.
Legionnaires’ disease is a serious form of pneumonia that can cause shortness of breath and gastrointestinal symptoms. About 10 percent of people who contract the disease die.
For this reason, you should also consider not putting ice in your drinks if possible, Dr. Detwiler to DailyMail.com.
He added: ‘Be careful about drinking tap water or using ice, especially when docking at foreign ports where water quality can vary.’
CUT AND PEEL YOUR OWN FRUIT
Instead of sliced fruit, Dr. Detwiler recommends selecting whole fruit from the dining areas and ‘cutting or peeling it yourself to prevent contamination’
While slices of melon and chunks of pineapple may look appealing on the buffets, Dr. Detwiler reveals that “pre-cut fruit carries a risk of being exposed to bacteria.”
In recent years there have been several outbreaks of bacteria linked to fruit. Most recently, in 2023, there was a nationwide outbreak of salmonella linked to melons, which sickened 407 people and killed six.
For this reason, Dr. Detwiler says he will “always avoid cantaloupe, as it often becomes contaminated and causes illness and death.”
Instead of cut fruit, he recommends selecting whole fruit from the eating area and “cutting or peeling it yourself to avoid contamination.”
SKIP STREET FOOD ON COUNTRY
The risk of stomach illness on cruises extends beyond the ship.
Most cruise lines offer shore excursions, where vacationers leave the ship and explore an area for a day, giving people a chance to sample the local cuisine.
But Dr. Detwiler warned against street food, especially when high temperatures can serve as a breeding ground for harmful bacteria.
He says: ‘When exploring port stops, be aware of food safety standards at local markets.
‘Stick to reputable restaurants and avoid street food that may not meet the same level of hygiene as the cruise.’