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Atlanta — From Miami, New York, Seattle and beyond, millions of Americans board cruise ships on vacation. But it’s not always smooth sailing when it comes to traveler health.
According to the U.S. Centers for Disease Control and Prevention, there have been 13 outbreaks of norovirus on cruise ships this year. This is the highest number of norovirus outbreaks on cruise ships recorded since 2012, with almost half the calendar year remaining.
The most recent norovirus outbreak occurred on a Viking cruise ship from Iceland that docked in New York City on June 20. About 13% of the passengers and several crew members fell ill on board.
“We believe the source of the gastrointestinal illness was a restaurant on the coast of Iceland where a group of guests were dining during their free time,” a Viking representative told CNN.
‘A virus with unusual infectivity’
Norovirus is a highly contagious virus that causes inflammation of the stomach and intestines, also known as acute gastroenteritis. Norovirus, often called the “stomach bug,” is the most common cause of nausea, vomiting, diarrhea and abdominal pain, according to the CDC.
People can become infected with norovirus through accidental ingestion of fine particles in feces or vomit. This can occur when you come into contact with an infected person, consume contaminated food or water, or touch contaminated surfaces. Symptoms usually last for only a few days, but can be contagious after 2 weeks or more.
“This is a highly contagious virus,” said Dr. William Schaffner, professor of infectious diseases at Vanderbilt University. “Only a few normal viral particles are enough for an exposed person to become infected. In other words, you don’t need a large dose. Just a little.”
There is no medicine to cure this disease, but most people recover completely without treatment. Rehydration therapy, which replaces fluids lost through vomiting and diarrhea, is standard treatment for symptoms.
Still, to help prevent the spread of norovirus, Schaffner recommends cruise passengers take extra precautions and wash their hands thoroughly with soap and warm water. Antiseptic gels and hand sanitizers are ineffective against viruses.
“When it comes to handwashing, we’ve all been doing it since we were kids,” says Jeffrey Fisher, associate professor of dietetics and dietetics at Central Michigan University. “But there are many studies that show that we don’t wash our hands often enough or not as often as we should, so we want to revisit the best handwashing practices. “
surge in cases
The exact cause of this year’s surge in cruise infections remains unclear, but experts suspect a surge in cruise demand and record passenger numbers are behind it.
The number of norovirus outbreaks on cruise ships docked at U.S. ports has been steadily declining for several years since 2015, according to data from the CDC’s Ship Sanitation Program. The overall incidence of acute gastroenteritis on US cruise ships also decreased from 2006 to 2019.
In response to the COVID-19 pandemic, the CDC has issued a travel health notice recommending travel by cruise ship due to safety concerns. CDC spokeswoman Kathleen Conley said cruises were restricted and there were few outbreaks due to reduced passenger numbers.
In fact, the program recorded no norovirus outbreaks in 2020 and 2021, likely due to restrictions on navigation and updates to sanitary protocols due to the COVID-19 pandemic. It is considered to be a thing.
But in March 2022, authorities lifted the risk advisory for cruise travel, and passengers are returning at a record pace.
With 31.5 million passengers expected to sail worldwide this year, surpassing pre-pandemic levels and creating a high-density environment ripe for infection.
The CDC releases outbreak information when more than 3% of passengers and crew report symptoms on cruises with 100 or more passengers traveling for 3 to 21 days.
These conditions have been met 13 times this year, up from two in 2022.
There have been four outbreaks of norovirus on Royal Caribbean ships this year, involving a total of 449 passengers and crew, the most by any individual cruise line, according to CDC data.
“The health and safety of our guests, crew and the communities we visit is our top priority,” a spokesperson for Royal Caribbean International told CNN in an email. “To maintain the highest levels of health onboard, we have implemented strict safety and cleaning procedures that far exceed public health guidelines.”
Compared to the general population, norovirus outbreaks on cruise ships are fairly rare. Between 19 and 21 million people in the U.S. are infected each year, according to the CDC, but thousands are infected on cruise ships.
Infections often occur in crowded environments where small particles are airborne, Schaffner said, and cruises could create the perfect environment for norovirus outbreaks. Having large groups living and eating nearby could be a breeding ground for the disease, he said.
“They are closed groups, very large, compact groups, often in very small spaces for long periods of time,” he said. “That’s why people meet so often that it’s relatively easy to get this virus.”
Norovirus symptoms can appear suddenly. Passengers may suddenly start throwing up while walking to their cabin or attending an event. The vomit is aerosolized, and fine airborne particles can infect nearby people.
“This highly contagious virus is being brought into the cruise ship environment, which is ideally designed for the rapid spread of epidemics,” Schaffner said.
Symptoms such as diarrhea and vomiting often go away in a few days, but they can also lead to dehydration. Schaffner warned that the cruise passenger base could be disproportionately made up of older people, but that rapid dehydration could create the risk of more serious illnesses. For diabetics, dehydration can derail treatment strategies.
Fisher attributes much of the problem to a “knowledge gap” about the virus among the public. As the COVID-19 pandemic appears to be winding down, “people are relaxing rather than staying alert to the spread of the disease.”
“I don’t think many people even understand norovirus, let alone how to protect themselves,” he said. “They are not taking precautions or appropriate protective actions that they have learned through the pandemic.”
Schaffner also suspects that people who felt sick before boarding are now more likely to leave. Many people longing for vacations after a two-and-a-half-year delay due to the pandemic could be bringing norovirus with them, he suggested.
“The first thing passengers can do is postpone their trip if they are not feeling well,” he recommended. “Try to limit other people’s exposure on the front end and take another cruise in a month.”
In addition to monitoring for disease outbreaks on board, the CDC’s ship health program mandates regular sick reporting from cruise ships, conducts regular spot checks, and implements public health guidelines for cruise ship employees. We also provide training for
As a precaution, the CDC advises passengers to wash their hands thoroughly, avoid contaminated food, and keep their hands away from their mouths. If a passenger becomes ill, both Schaffner and the CDC recommend that they remain in their cabins and notify the ship’s medical team immediately.
“Let them take over and take care of you,” says Schaffner. “Don’t go out and spread the virus.”