What is hantavirus, the deadly disease aboard a cruise ship?

STORY: Three people have died in an outbreak of a rat-borne disease on a luxury ship.

So what exactly is hantavirus, and should you be worried about it spreading?

:: How is hantavirus transmitted?

"They're relatively rare infections."

Daniel Bausch is a specialist in tropical diseases at the Geneva Graduate Institute in Switzerland.

He said the virus is only rarely passed between humans and is most commonly spread when people have contact with rodent droppings, urine, or saliva.

But a cruise ship might create the conditions person-to-person infection.

"We know that cruise ships and other events where we pack a lot of people into small places, that they always have the risk of human to human transmission of different pathogens."

:: What are the symptoms of hantavirus?

Hantavirus usually begins with flu-like symptoms, such as fatigue and fever.

Four to 10 days later, coughing, shortness of breath and fluid in the lungs appear.

"And so we can see in hantaviruses that people develop essentially a pneumonia or a consolidation of fluid filling up in their lungs. And that can happen very rapidly."

:: Is there a cure?

Bausch says there's no specific antiviral drug for hantaviruses. Treatment, he says, often requires hospitalization in an intensive care unit.

"It's not the sort of treatment that is generally available on a cruise ship."

:: What caused the outbreak?

The World Health Organization said it's been told there were no rats aboard the ship.

Its working assumption was that the cases originated in a Dutch couple, who joined the ship in Argentina. 

That couple may have been infected before joining the cruise.

"Hantaviruses have, or can have, at least, a relatively long incubation period. Incubation period is the time from when you get exposed to something to when you fall sick. And so in hantaviruses, that can be, in extreme cases, up to six weeks." 

:: Is there a risk of a wider outbreak?

The World Health Organization assesses the overall public risk from this current outbreak to be low. 

"This is not the next COVID-19. This is not going to be a big outbreak. This is not a reason for your average person in the world to panic at all." //  "If you had tickets for a cruise, I don't think you need to cancel it. And now that you know that it's possible because it's pretty rare."