The state’s Department of Public Health said Thursday that the family from Los Angeles County camped at Yosemite’s Crane Flat Campground in mid-July and visited other places in the Stanislaus National Forest. No other family members became sick, and the child is recovering.
Plague is carried by rodents such as squirrels and spread when fleas carry the disease from a dead rodent to other animals or people.
Officials say it is not transmitted between humans, except in the rare cases. Plague can be fatal if left untreated.
Symptoms include fever, chills, nausea and swollen lymph nodes.
Since 1970, 42 people in California have contracted plague resulting in nine deaths.