90-Second Read: Is Hantavirus contagious? Here's how it spreads and why Andes virus is different

Countries around the world are preparing to deal with the more than 140 passengers and crew members on board a Hantavirus-stricken cruise ship. An outbreak aboard a cruise ship of a rare rodent-borne illness called Hantavirus has left three passengers dead and sickened others, but how dangerous is it? Typically, Hantavirus doesn't spread from human-to-human but in the case of this outbreak, health officials suspect it may be caused by the one strain that can. Hantavirus is usually spread by the inhalation of contaminated rodent droppings and isn't easily transmitted between people.

The Andes virus is a concerning member of the Hantavirus family. The only Hantavirus thought to spread human-to-human, it can cause a severe and often fatal lung disease called Hantavirus pulmonary syndrome. The passengers included a resident of the remote island of Tristan da Cunha who has been hospitalized with symptoms of Hantavirus, according to the British Foreign Office. But exactly how contagious is the virus and how does it spread?

A flight attendant who had contact with her has tested negative for Hantavirus after reporting symptoms. Hantavirus is mainly spread by contact with rodents or their urine, saliva or droppings, particularly when the material is disturbed and becomes airborne, posing a risk of inhalation. People are typically exposed to Hantavirus around their homes, cabins or sheds, especially when cleaning enclosed spaces with little ventilation or exploring areas with mouse droppings. Hantavirus pulmonary syndrome is fatal in about 35% of people infected, while the death rate for hemorrhagic fever with renal syndrome varies from 1% to 15% of patients, according to the CDC.

The other syndrome caused by Hantavirus, known as hemorrhagic fever with renal syndrome, which can cause bleeding, high fever, and kidney failure, usually develops within a week or two after exposure. Death rates vary by which Hantavirus causes the illness. At least seven Americans who were on the vessel are isolating at home across five states, and none show any symptoms of the virus, according to local health officials.