A hantavirus outbreak on a cruise ship has raised concerns.

The ship docked in Spain, and passengers went home.

Four Canadians are self-isolating in B.C. after the outbreak.

Send your hantavirus questions to ask@cbc.ca.

Six Canadians are self-isolating due to possible contact with hantavirus cases.

None of the Canadians have been tested or show symptoms.

Experts answer questions about hantavirus.

The most common hantavirus strain in Canada is Sin Nombre.

The Andes strain hasn't circulated in Canada, says Dr. Safronetz.

Canada's cold winters prevent the Andes virus from establishing roots.

The Sin Nombre strain causes severe respiratory illness.

What is hantavirus?

Hantavirus has a high death rate of 30-40%.

The overall risk in Canada is low, with 170 cases reported.

Three rodents in Canada carry hantavirus: deer mouse, white-footed mouse, and red-backed vole.

Many hantavirus cases were in the Prairies, with Alberta reporting the most.

Clean and disinfect areas contaminated with rodent droppings.

It's not fully known how the Andes hantavirus spreads between people.

The virus spreads between people in close and prolonged contact.

The World Health Organization suggests a distance of 2 meters for 10-15 minutes.

Hantavirus spread: Doctor explains what you need to know

People infected with the Andes strain spread it through close contact.

The virus spreads through speaking, singing, coughing, and oral secretion sharing.

Close contact is needed for the virus to spread, unlike measles or influenza.

Someone with high amounts of the virus in their saliva can spread it more easily.

Four Canadians will begin a three-week isolation period in B.C.

Their self-isolation started on the ship after the outbreak was confirmed.

Isolation guidance is based on when public health officials believe they were first exposed.

Most people will show symptoms within a 30-day window.

The decision to send people home was likely due to a lack of medical resources on the ship.

Isolating on a cruise ship doesn't fit with the severity of the disease.

If someone tests positive and is asymptomatic, they might spread the virus, but it's unlikely.

If you're healthy and don't have symptoms, the risk is low.

Transmission can happen 48 hours before someone shows symptoms.

The risk increases when someone starts showing symptoms.

Health officials in Canada aren't testing passengers without symptoms.

Some countries are testing on a case-by-case basis.

One asymptomatic American has tested positive.

There are two ways to test for hantavirus: PCR or serology.

A positive serology test indicates an immune response to the virus.

A positive PCR test suggests the person currently has the illness.

If someone has a confirmed case, they probably had a positive test.

If your pet is a rodent, it can carry hantavirus.

There have been cases where people with pet rodents were infected with hantavirus.

You can't get hantavirus from your cat or dog, but beware if they hunt rodents.

If you have a pet that hunts rodents, be cautious when disposing of them.

Cleaning up dead rodents can present a risk, so take proper precautions.