Hantavirus Dispatch: Yosemite 'tent cabin' design may have allowed scat accumulation, protected it from deactivating UV rays

January 12th, 2015

Prior to 2012, only 2 cases of hantavirus infection had been identified in visitors to California’s Yosemite National Park – one in 2000 and another in 2010. Both infections were acquired in the Tuolomne Meadows area, miles distant from the iconic Yosemite Valley. Things changed this summer with 9 new cases identified as of September 13, only one of which was associated with visiting the High Sierra Camps of Tuolomne.

The other 8 had stayed in the Curry Village area of the Yosemite Valley, all in “Signature Tent Cabins”. These 91 relatively new cabins set off to one side of Curry Village have double-walls, which provides an element of insulation – but also presumably provides a site for rodent excreta to accumulate, while also possibly reducing ambient air exchange. Hantavirus, which may survive for as long as 13 days in the environment, would be protected from inactivating UV rays at this site.

The first case occurred in a visitor who stayed in Curry Village from June 10-12 and became ill on June 26. The Signature Tent Cabins were closed on August 28. Seven of the patients were residents of California, while one each was from Pennsylvania and West Virginia. Three of the 9 have died. Initial notifications were made in August to 30,000 visitors and on September 12th email notifications were sent to 230,000 overnight visitors. Approximately one-tenth of visitors are international and public health officials of 39 countries have also been notified of the outbreak and its consequences.

-- Stan Deresinski, MD, professor of infectious diseases, Stanford University