The source of the norovirus outbreak remains unknown, but sick hikers on the Pacific Crest Trail were observed near a shared water cache last week.
FILE: Hikers heading south descend from Mather Pass on the Pacific Crest Trail in Kings Canyon National Park, Calif.
David Madison/Getty Images
An outbreak of the highly contagious norovirus seemi… [+8732 chars]
David Madison/Getty Images
An outbreak of the highly contagious norovirus seemi… [+8732 chars]