A South Lake Tahoe resident has recently been tested positive for plague, marking the first human case in California in five years. The last case in California was seen in 2015.

According to a press release from the El Dorado County Health and Human Services Agency, health officials believe that the person may have been bitten by an infected flea while walking a dog in the area.

The infected person has been recovering at home under the supervision of a medical provider, according to the release.

Plague is an infectious disease caused by Yersinia pestis bacteria, usually found in small mammals and their fleas, according to the World Health Organization (WHO). The disease is transmitted between animals via their fleas and, as it is a zoonotic bacterium, it can also transmit from animals to humans.

The signs and symptoms of plague appear within a couple of weeks of exposure, which include fever, weakness, nausea, and swollen lymph nodes. The disease is treated with antibiotics when detected early enough.

The health officials are still investigating the circumstances of the case after the California Department of Public Health reported the positive test result.

El Dorado County Public Health Officer Dr. Nancy Williams said, “Human cases of plague are extremely rare but can be very serious,” adding that plague is naturally present in most parts of the state.

“It’s important that individuals take precautions for themselves and their pets when outdoors, especially while walking, hiking and/or camping in areas where wild rodents are present,” she added.

In California, the last confirmed case of plague was reported in 2015, when two people were exposed to infected rodents in Yosemite National Park. Both of them were treated and recovered. Prior to that, there had not been a plague case in California since 2006.

The United States has reported an average of seven cases of human plague each year in recent decades, with a range of one to 17 cases per year, according to the Centers for Disease Control and Prevention (CDC). Earlier in August, a New Mexico resident in his 20s died from the septicemic plague, the second confirmed case of 2020.