Sanjay Gupta

That's a remote island in the South Atlantic Ocean.

This was part of a scheduled disembarkment before hantavirus was confirmed aboard the ship.

So yes, people had gotten sick, but they weren't sure what it was at the time these passengers disembarked.

Those passengers live in several states, Arizona, California, Georgia, Texas, and Virginia, as well as other countries.

What's happening now is public health officials have been working to track them down for testing and monitoring.

This is a group of viruses that are spread mainly by rodents through their bodily fluids and their feces.

How does infection happen?

Well, humans often become infected when they inhale particles from dry rodent droppings.

I know, it's kind of gross.

Typically, it happens when someone tries to dispose of rodent droppings by sweeping them up.

that may cause the particles to become airborne.

And the most common hantavirus in the United States is spread by the deer mouse.

Humans can also become infected by touching contaminated objects and then touching their mouth or nose.

Hantavirus can also spread through rodent bites or scratches, though that is actually pretty rare.

Now, one Hantavirus strain, the Andy strain, is native to South America.

It was first discovered in 1995, and it's really the only one known to spread from person to person.

Again, rarely.

This is the strain that scientists believe might be responsible for the outbreak on the cruise ship.

In fact, what we know now is that four of the five sick cruise ship patients are confirmed to be infected with the Andy strain of the virus.

Again, what makes this outbreak unique is that the evidence points to it being caused by this particular strain of hantavirus, which is known to have had limited spread between people in the past.