90-Second Read: How worried should you be about Hantavirus?

News of a Hantavirus outbreak aboard an expedition cruise ship has put a spotlight on the rare but potentially deadly disease. Here's what she says the public needs to know about Hantaviruses, the ship outbreak, and how to protect against the rodent-borne disease: Hantaviruses are a broadly distributed group of viruses that have been found in Europe, Asia, and the Americas. Fatality rates for the more serious Hantavirus cardiopulmonary syndrome depend on the strain, and can be deadly in about 3 to 4 out of every 10 people. A researcher answers questions about the rare rodent-borne virus that caused a deadly cruise ship outbreak. As of May 6, three passengers have died from acute respiratory illness and several additional cases are suspected among the other passengers and crew.

Marieke Rosenbaum, assistant professor in the infectious disease and global health department at Cummings School of Veterinary Medicine at Tufts University, has been investigating whether rats in Boston carry Hantavirus. But one that does is the so-called Andes strain, which now has been identified as the Hantavirus behind the confirmed cases from the ship. Human cases of Hantavirus usually are the result of mouse infestations and human exposure to contaminated dust. The "new world" Hantaviruses, which were more recently discovered in the Americas, cause the deadliest form of the disease, the severe respiratory illness known as Hantavirus cardiopulmonary syndrome. Most strains of Hantavirus are not known to spread from person to person.

Health officials are investigating whether the virus, which is typically spread from rodents to humans, may in this case have spread between people on board the ship, a rare but concerning possibility. Hantavirus infections can start as a flu-like illness with fever. Human-to-human spread of Hantavirus is rare and typically requires very close contact. And as Hantaviruses continue to evolve, we need to better understand which genetic changes in the virus may lead to strains that spread more easily among humans or cause more severe symptoms. The type of disease caused by various strains of Hantaviruses typically depends on where you are in the world.

We know that there is genetic diversity within Hantavirus, for example, although the Andes strain can be transmitted from person to person, most Hantaviruses are unlikely to. Very little surveillance has been done on Hantaviruses in wild rats in the US, even though the brown, or Norway, rats common in cities are known to carry these viruses globally. There is no treatment for any form of disease caused by a Hantavirus other than to provide supportive care. People most often become infected with Hantavirus through contact with contaminated urine, droppings, or saliva from wild rodents, especially mouse urine. Common places for potential Hantavirus exposure include attics and basements, as well as sheds, garages, vehicles, and campsites.