August 23, 2017 – As a public safety precaution, the Army Corps of Engineers working in coordination with California Department of Public Health (CDPH) Vector-Borne Disease Section will be placing insecticide-treated rodent bait stations throughout the Alpine Meadows campground at Martis Creek Lake to control the elevated number of fleas observed on golden-mantled ground squirrels, chipmunks and Belding’s ground squirrels. Rodents that enter the tubes to feed on bait will come into contact with insecticide treated carpet. The treatment will help reduce the number of fleas on rodents and decrease the potential transmission of plague to humans. The Army Corps of Engineers will also be posting yellow Plague Warning Signs throughout the area.

Nevada County Environmental Health/Vector Control Staff were notified by the CDPH Vector-Borne Disease Section of an increased risk of plague in the Alpine Meadows campground area. Historically, plague is endemic in much of Sierra Nevada and rodent species have tested positive for plague in 2000, 2004, 2005 and 2012 in the Martis Creek Lake area. There have been no human plague cases associated with the Martis Creek Lake area.

Plague is an infectious disease caused by the bacterium Yersinia pestis. Today, plague in humans is rare in the United States and can be treated effectively with antibiotics if diagnosed early. Plague is most common in the foothills and mountainous areas of California. It is absent from the southeastern desert region and the San Joaquin Valley. Rodents and their fleas maintain plague bacteria in nature. The major threat of plague is from wild rodents, primarily chipmunks and ground squirrels, in rural recreational and wilderness areas.

People become infected with plague bacteria most commonly through the bite of an infected flea. Infection is also possible when the blood or other body fluids of an infected animal enter through cuts or breaks in the skin or mucous membranes (eyes, mouth, and nose). Cats are especially susceptible to plague and, if infected, represent a serious source of potential human exposure. Cats may also transport infected rodent fleas into a home or campsite.

As a health and safety precaution, the Nevada County Environmental Health Department recommends the following:

– Be aware of areas in which plague-infected rodents might exist.
– Follow the instructions on plague notices that are posted at the Martis Creek Lake camping and recreation areas.
– Avoid all contact with rodents and their fleas, especially sick or dead rodents.
– Store food and garbage in rodent-proof containers.
– Do not feed rodents in campgrounds and picnic areas.
– Do not place chairs, tents, or sleeping bags near rodent burrows.
– Wear long pants tucked into boots and use insect repellent to avoid flea exposure.
– Do not allow pets to approach sick or dead rodents, or to explore rodent burrows.
– Be cautious when handling ill cats that may have had contact with wild rodents; take ill cats to your veterinarian for examination.

The initial symptoms of plague develop two (2) to six (6) days after exposure and include nausea, vomiting, fever, chills, muscle aches, headache, and weakness. Three forms of plague are known: bubonic, septicemic, and pneumonic. Bubonic plague, the most common form, is characterized by swollen and tender lymph nodes (called “buboes”) in the groin, neck, or armpit. In septicemic plague, plague bacteria enter the bloodstream, causing high fever, fatigue, weakness, and bleeding disorders. Pneumonic plague is an infection of the lungs that can follow bubonic or septicemic plague, or occur directly from inhalation of plague bacteria. Patients with pneumonic plague have difficulty breathing, develop a cough, and may spit up blood-tinged saliva.

If you become ill within seven (7) days of being in a plague area with any of the symptoms listed above, contact your physician immediately.

Nevada County Environmental Health/Vector Control Staff will remain in contact with the CDPH Vector-Borne Disease Section for updates on CDPH surveillance conducted subsequent to the placement of the bait tube insecticide treatments throughout the campground and recreation areas.

For more information on plague, including risk assessment and risk reduction measures for recreational areas can be found at: