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Yosemite Hantavirus Outbreak

by Daniel J. DeNoon

Some 3,000 families have now received emails or letters warning them that they might have caught deadly hantavirus disease while visiting Yosemite National Park this summer.

Six visitors have come down with hantavirus pulmonary syndrome. Two died. Symptoms may not appear for six weeks after infection — so the estimated 10,000 Yosemite visitors who received warnings are waiting anxiously for signs they might have to rush to a hospital.

All of the reported cases were among park visitors who stayed in the “Boystown Signature Tent Cabins,” numbered in the 900s. It’s a group of permanent tent structures in one corner of the Curry Village area of Yosemite.

So far, all the reported infections happened in mid-June. But notices have been sent to everyone who stayed in the Boystown area from June 10 to August 24.

The strain of hantavirus found in the Yosemite area is called Sin Nombre virus. It’s spread by deer mice. Mouse urine and droppings mix with dust, and when that dust gets stirred up and breathed in, the virus can infect the lungs.

The notices sent to Boystown visitors warn them to be on the alert for fever, aches, and flu-like symptoms. These symptoms can rapidly worsen, so people with possible hantavirus exposure should immediately seek care at the first sign of illness.

Yosemite officials note that there have been no hantavirus infections outside the Boystown Signature Tent area or before mid-June.

“Individuals who visited Yosemite outside of this area and time frame, but who are experiencing flu-like symptoms should use their own discretion regarding contacting their health care provider. Early medical attention is critical for individuals who contract hantavirus,” the Yosemite web site warns.


The opinions expressed in WebMD Second Opinion are solely those of the User, who may or may not have medical or scientific training. These opinions do not represent the opinions of WebMD. Second Opinion are... Expand


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