FILE - In a Tuesday Aug. 28, 2012 photo, Glenn Dean, a National Parks Occupational Safety and Health Specialist, inspects tent cabins for mice entry points at Curry Village at Yosemite National Park. Two more Yosemite National Park visitors have been found with a mouse-borne virus blamed for the deaths of two people, bringing the total number of infections to six, state health officials said. (AP Photo/San Francisco Chronicle, Michael Macor)

Photo by: Michael Macor

FILE - In a Tuesday Aug. 28, 2012 photo, Glenn Dean, a National Parks Occupational Safety and Health Specialist, inspects tent cabins for mice entry points at Curry Village at Yosemite National Park. Two more Yosemite National Park visitors have been found with a mouse-borne virus blamed for the deaths of two people, bringing the total number of infections to six, state health officials said. (AP Photo/San Francisco Chronicle, Michael Macor)