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Months after it was first discovered, the new coronavirus — known only as 2019-nCoV — has infected more than 37,500 people and has killed more than 800.

As health authorities scramble to contain the virus, the spotlight has been put on cruise ships where a number of infections have been identified.

In Japan, 3,700 people — including 251 Canadians — have been quarantined aboard Princess Cruises’ Diamond Princess after a number of passengers tested positive for the virus last week.

READ MORE: ‘We do get fresh air’ — Edmonton couple trapped on ship quarantined over coronavirus

On Sunday, health authorities announced another six people had tested positive for the virus, bringing the total number of cases aboard to 70.

But, the Diamond Princess is not the only affected cruise ship that has been affected by the new coronavirus.

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4:08 Alberta couple under coronavirus quarantine on cruise ship Alberta couple under coronavirus quarantine on cruise ship

Concern over the virus prompted Royal Caribbean Cruises to announce it would ban all passengers with Chinese, Macau or Hong Kong passports from its trips last week.

On Wednesday, Taiwan’s health authority banned all international cruise ships from docking over the threat of coronavirus.

Late last week the Japanese government didn’t allow another cruise ship, Holland America Line’s Westerdam, to dock, even though no cases of the virus had been reported on board.

Over the weekend, two cruise ships — the SuperStar Aquarius and the Dream World — allowed 1,700 and 1,800 people respectively to disembark after each was quarantined temporarily over coronavirus fears.

Are these types of viral outbreaks commonplace on cruise ships? How can you protect yourself?

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Here’s what experts say.

A ‘perfect setup’ for infectious disease transmission

According to Dr. Isaac Bogoch, an infectious diseases faculty member at the University of Toronto, cruise ships, or any space where a large number of people are confined to small areas, are “the perfect setup for infectious disease transmission.”

“It’s not unheard of for infectious diseases to spread on cruise ships,” he said. “But I really think the key is anytime people are in close quarters with one another, it’s a perfect setup for not just gastrointestinal, but also respiratory tract infections to spread as well.“

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Bogoch said most often, norovirus or gastrointestinal (GI) bacterial infections are what spread on cruise ships.

“These are viruses that can cause primarily a gastrointestinal syndrome, nausea, vomiting, sometimes diarrhea,” he said.

According to Bogoch, people usually become infected by consuming contaminated food or water.

READ MORE: Vancouver couple on board cruise ship stranded outside Taiwan

Dr. Jason Kindrachuk, an assistant professor and Canada Research Chair in emerging viruses at the University of Manitoba, said these types of norovirus and GI tract bacteria outbreaks are often seen on cruises because of how they are transmitted.

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He said those types of pathogens often appear when people are sharing the same food source.

“When you have a lot of people that are in a confined vessel and they’re all sharing common food — and obviously, you have buffet-type food sources and stuff — it just it makes things a lot easier for being able to transmit those types of pathogens,” he said.

1:04 Health screening begin aboard quarantined Japanese cruise ship after positive coronavirus case Health screening begin aboard quarantined Japanese cruise ship after positive coronavirus case

According to the U.S. Centre for Disease Control and Prevention (CDC), in 2019 alone there were eight confirmed outbreaks of norovirus on seven different cruise ships.

The Royal Caribbean’s Oasis of the Seas cruise saw the worst norovirus outbreak in January of last year when 561 people on the ship became ill.

What’s more, the CDC said viral outbreaks on ships can be sustained for multiple voyages by transmission among crew members who remain onboard or by “persistent environmental contamination.”

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Sometimes, travellers can be exposed to local diseases when at port, which are then brought back on board.

How is coronavirus spreading on cruise ships?

According to Kindrachuk, health officials believe the main way coronavirus is spread is through droplets.

“If somebody coughs or sneezes in close proximity, you can pick up some of the droplets and obviously the virus that way,” he explained. “So on a cruise ship, arguably, there is a possibility that, I think, people could see the greater amount of transmission.“

READ MORE: 5 Canadians among 41 new cases of coronavirus on cruise ship docked in Japan

Kindrachuk said that is why officials have imposed the quarantine, to really “nail down” whether there are a number of “secondary transmission” cases on the affected cruise ships.

“Once you have one person that is showing signs or when a person tests positive, until you can basically distinguish that any of the people that are in close proximity or whether they’re negative or positive, you don’t want to release those people, and create a walking source of the virus,” he said.

2:11 Hundreds of Canadians under quarantine on cruise ships Hundreds of Canadians under quarantine on cruise ships

According to Bogoch, it’s “too soon to tell” if the virus is spreading faster than other more common types of infection found on a cruise ship would.

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He said, though, that evidence has shown the new coronavirus may able to survive on surfaces for a few hours, potentially up to “a day or so.”

“Certainly if this virus landed on a high contact surface and then someone touched that surface and picked up that virus on their hand and then maybe touched their mouth, they could certainly be infected,” he said.

How can you protect yourself?

According to the CDC, before leaving for a cruise, passengers should consult their healthcare providers and should evaluate the type and length of their planned cruise.

The centre says passengers should also check to see if any health notices or gastrointestinal outbreaks have been posted online before departing.

According to Bogoch, once on a cruise, the best way to prevent getting sick is by practising “impeccable hand hygiene.”

“Cough and sneeze into your arm and wash your hands are the best pieces of advice,” he said. “Of course those aren’t perfect, but they may reduce someone’s risk.”

However, Bogoch said that on a cruise or in another confined space, this still may not totally eliminate your risk of becoming sick.

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The CDC recommends travellers follow “safe food and water precautions” when eating off the ship.

1:02 Coronavirus outbreak: Seven Canadians have tested positive for virus aboard cruise ship in Japan Coronavirus outbreak: Seven Canadians have tested positive for virus aboard cruise ship in Japan

The centre says travellers should “maintain good fluid intake,” should avoid consuming excessive amounts of alcohol, and should avoid coming into contact with sick people.

Kindrachuk said if you are feeling unwell, the best thing you can do is self-report to healthcare professionals.

“We just need to do the very basic things that we can do to try and ensure that we’re not passing those [germs] on to other people or that we’re ensuring that we don’t pick them up,” he said.

—With files from The Associated Press and Reuters