YOSEMITE, Calif. (KSEE/KGPE) – Posters warning visitors about the plague have been catching the eye of Yosemite National Park visitors - but, rangers say the signs are merely cautionary. In the photo below, a plague notice posted in the Mariposa Grove Welcome Plaza (spotted at the end of December) advises visitors on how to avoid being infected. Why Yosemite visitors need to be careful of the 600-year-old plague Park service says there have been no recent plague incidents and the poster is one of the routine "safety messages posted around the park." The California Department of Public Health (CDPH) says that posters are intended to communicate that plague could be circulating as the bacteria that cause the disease are widespread in much of the state, including in the Sierra Nevada mountains and foothills; the messages do not indicate plague activity. ‘A very gratifying experience’: Yosemite meadow thriving after years of restoration Although the plague is rare and is treatable with antibiotics, the CDPH warns that it is a serious bacterial disease and can progress to a fatal illness if diagnosis and treatment are delayed. Plague bacteria is transmitted through physical contact with an infected animal. Although usually transmitted through rodents or fleas, cats and dogs can also become infected and transmit the disease to their owners.