A Los Angeles County child became ill with human plague and was hospitalized after visiting the Stanislaus National Forest and camping in Yosemite National Park in mid-July, according to state health officials. The child is recovering.
It's California's first case of human plague since 2006.
State health officials are investigating the case and conducting an environmental evaluation in the forest, the national park and the surrounding areas.
They are working with the L.A. County Department of Public Health, the Centers for Disease Control and Prevention, the U.S. Forest Service and the national park to investigate the source of the infection, and the patient's travel history and activities during the incubation period.
Plague is an infectious bacterial disease that is carried by squirrels, chipmunks and other rodents and their fleas, according to health officials. When an infected rodent becomes sick and dies, its fleas can carry the infection to other warm-blooded animals or humans.
In California, these animals are most likely to be found in the foothills and mountains and, to a lesser extent, along the coast. In 2014, non-human plague activity was detected in animals in seven counties, including San Diego and Santa Barbara counties, according to the state health department.
Plague is not transmitted from human to human, unless someone sickened with plague also has a lung infection and is coughing. There have been no known cases of human-to-human infection of plague in California sine 1924. State and county officials say they believe the risk in this case is similarly low.
The disease has been around for centuries: A plague pandemic, widely known as the Black Death, originated in China in 1334 and spread along trade routes to Europe, where it claimed an estimated 60 percent of the European population, according to the CDC.
But don't expect this case to spur another huge outbreak. The pandemics of the past resulted from rodents living in urban dwellings; there was also significant human-to-human transmission.
Today, plague is a rural disease that is readily treated with antibiotics, says Vicki Kramer, chief of the state health department's vector borne disease section. It's also rare: Since 1970, the state has reported 42 human cases, nine of which were fatal.
"The risk of getting plague in California is very low," Kramer says. "But despite that low risk, we still recommend that people take precautions to avoid rodents and their fleas."
Those precautions include:
- Never feed squirrels, chipmunks or other rodents
- Never touch sick or dead rodents
- Avoid walking, hiking or camping near rodent burrows
- Wear long pants tucked into socks or boot tops to reduce exposure to fleas
- Spray insect repellent containing DEET on socks and pant cuffs to reduce exposure to fleas
- Keep wild rodents out of homes, trailers and outbuildings, and away from pets
Early symptoms of plague include high fever, chills, nausea, weakness and swollen lymph nodes in the neck, armpit or groin. While treatable in its early stages, the disease can be fatal if left untreated.
If you develop these symptoms, you should seek immediate medical attention. Be sure to notify your health care provider if you've been camping or out in the wilderness, and have been exposed to rodents and fleas.