The outbreak has sickened dozens of people in a number of states, and officials say it could spread to other states.
Agency officials said the outbreak has prompted a ban on outdoor food service at many restaurants and a temporary restriction of many outdoor festivals.
Officials also say they are trying to figure out how to combat the spread of the disease.
The California Department of Public Health says it has been overwhelmed by calls and emails about the outbreak.
Officials say that they are investigating more than 30 cases.
Officials are also warning that people should wear masks when outdoors and not let children play in the woods, because of the risk of catching the disease in the process.ABC News’ Jon Allen, Daniella Zaborek and Matt Parnes contributed to this report.