(San Bernardino, CA) -- Dozens of hikers have gotten sick on the California section of the Pacific Crest Trail stretching from Mexico through Oregon and into Canada. The Pacific Crest Trail Association says it knows about reports of stomach illness in the Wrightwood area of San Bernardino County. Seven to twelve cases have been confirmed as norovirus. Norovirus, also referred to as the stomach flu, causes vomiting and diarrhea. The first reports of illness on the trail came in early May. The hiking trail runs along the west coast's highest mountain ranges through California, Oregon, and Washington.