The California Department of Public Health announced "a presumptive positive case of plague" involving someone from Georgia who had spent time in early August in the state.
Before feeling sick, this person visited Yosemite, the Sierra National Forest and nearby areas. No other details were given, including who the person is, their current medical condition, and where exactly he or she stayed overnight. Nor is it certain this person contracted the plague while in California.
Still, the report suggests that two people recently in California have a disease best known for killing millions centuries ago that -- despite all the advances of modern science -- remains a real present-day problem.
In addition to the California cases, two people contracted the plague this year in Colorado. Both of them, a teenager in Larimer County and the other an adult in Pueblo County
, died of the disease.
Pair of Yosemite campgrounds treated
News of the latest probable plague case in California comes just after Yosemite National Park shut down its Tuolumne Meadows Campground after authorities determined two dead squirrels had the plague.
The campground will be closed from Monday through Friday. It is one of 13 around Yosemite, which with about 4 million visitors is the third most visited U.S. national park.
Staff will treat the Tuolumne Meadows site with deltamethrin, a chemical that kills fleas that spread the plague, according to the park.
The first Yosemite campground to get the once over was Crane Flat, which is where a child -- after visiting nearby Stanislaus National Forest -- had stayed in mid-July. In that case, an insecticide that contained deltamethrin was used on rodent burrows on August 10 and 11.
That child is recovering from the plague, and no other members of the camping party have reported any related symptoms, according to authorities.
Teen, adult with plague die in Colorado
Medicine has come a long way since the the Black Death during the Middle Ages, with antibiotics and antimicrobial medicines among the tools to aid those with the plague. But it hasn't eliminated the disease entirely, including in developed countries like the United States.
The Centers for Disease Control and Prevention reports that the United States has about seven annual cases, over 80% of which have been in the bubonic form
Thus, the four human cases reported so far in 2015 appears to be in line with those numbers.
Until now, California hadn't had an instance of human plague since 2006, when there were three cases in Mono, Los Angeles and Kern counties, according to state health officer Dr. Karen Smith. There have been 42 cases in the state since 1970, of which nine proved fatal.
"Although this is a rare disease, people should protect themselves from infection by avoiding any contact with wild rodents," Smith said.