10,000 Possibly Exposed to Hantavirus at Yosemite National Park

Posted on September 4, 2012

Sin Nombre Virus


As many as 10,000 people were exposed to hantavirus at Yosemite National Park. The virus is spread through contact with mouse droppings and urine. Early symptoms include fatigue, fever, muscle aches, headaches, dizziness, chills and abdominal issues. The more serious and potentially deadly respiratory problems associated with the illness develop about four to ten days after the initial onset of symptoms. The CDC lists the mortality rate as 38%. There is no cure.

Hantavirus is rare. CNN Senior Medical News Correspondent Elizabeth Cohen reports that there have been just 602 cases in the U.S. since 1993 according to CDC data.

The Yosemite hantavirus situation is a unique one where thousands of people were potentially exposed while staying at the Signature Tent Cabins in Curry Village at Yosemite National Park. CBS News reports that the people exposed stayed in the cabins between June and August. CBS News also reports that it is believed infected mice were living between the walls of these cabins.

Six people have been confirmed to have contracted hantavirus from Yosemite according to the latest figures. Two people have died. The L.A. Times says five of the six cases were linked to the tent cabins. CBS News reports that it can take as long as six weeks before people who come down with illness begin having respiratory problems. The CDC says the exact incubation period is "not positively known" but it is thought symptoms develop between 1 week and 5 weeks after exposure. The lack of precise information on the incubation period is due to the small number of Hantavirus Pulmonary Syndrome (HPS) cases.

WedMD is reporting that the particular strain of hantavirus at Yosemite is the Sin Nombre virus, which is spread by deer mice. WedMD says the hantavirus in mice droppings and urine gets mixed up with dust particles and can be inhaled when the dust is stirred up. This is why advisories for cleaning up after mice invasions into homes is very strict, such as not to use a vacuum or sweep because you could spread the potentially dangerous dust particles into the air where they could be more easily inhaled.

The image above shows a transmission electron micrograph (TEM) of the Sin Nombre virus (SNV) from the November 1993 Four Corners outbreak.

Photo: Cynthia Goldsmith/CDC