Plague in ground squirrel populations in the desert south of Boise continues to be a concern as schools in the Treasure Valley begin summer vacation this week. Public health officials are reminding people to be aware and to take precautions if they live in or are recreating in the affected area.
So far, there are no confirmed cases of the plague in people or pets. And we’d like to keep it that away for as long as possible. As Idahoans prepare for the first weekend that kids are out of school, please take a few moments to read up on the disease and review what you need to do to protect your family, yourself, and your pets.
Here are some frequently asked questions to get you started. You can read our previous blog post here, as well as see a map of the affected area here. This map is interactive; you can type in your address to see if your home is in the area where plague has been confirmed in the resident ground squirrels.
What causes plague and how is it transmitted?
Plague is a disease caused by the bacterium Yersinia pestis. The bacterium lives in several rodent species. When fleas feed on infected animals, the fleas become infected and spread the bacterium when they bite other animals and humans. When infected animals die, fleas will seek live animals, including humans, to feed on. With the current die-off of ground squirrels in the area, fleas from these animals will be hungry. Fleas can jump off of dead ground squirrels or from around abandoned burrows, and bite and potentially infect pets or people that get too close. Avoiding dead ground squirrels and their abandoned burrows is a good way to avoid exposure. Plague can also be transmitted when someone is exposed to tissue or body fluids of an infected animal. It also can be spread by droplets when an animal or person who has plague pneumonia coughs.
What are the symptoms of plague in people?
Plague is a life-threatening illness. It can cause three types of illness in people:
- Bubonic plague usually results from the bite of an infected flea. People ill with bubonic plague have sudden onset of fever, headache, chills, and weakness and one or more swollen, tender and painful lymph nodes (called buboes).
- Septicemic plague may result after handling an infected animal, the bite of an infected flea, or it may result from untreated bubonic plague. Infected people have fever, chills, extreme weakness, abdominal pain, shock, and possibly bleeding into the skin and other organs. Skin and other tissues may turn black and die, especially on fingers, toes, and the nose.
- Pneumonic plague occurs from septicemic plague or from inhaling infectious droplets from an animal or another person with pneumonic plague. Sick people have fever, headache, weakness, and a rapidly developing pneumonia with shortness of breath, chest pain, cough, and sometimes bloody or watery mucous.
What are the signs of plague in cats and dogs?
Plague can be life-threatening in pets. Cats generally get much sicker than dogs and are likely to die if they do not get veterinary care soon after they become ill. Cats can develop bubonic, septicemic, and pneumonic forms of plague, just like people. Cats can spread plague to people if they have the pneumonic form, by coughing.
Dogs usually have a mild illness, but they, too, can get seriously ill.
If your dog or cat has been to an area with dead ground squirrels and is not as active as usual, not eating, or has a fever, seek veterinary care for them immediately and tell the veterinarian that your pet was potentially exposed to plague.
What if I feel ill and was around dead ground squirrels or their fleas in an area where there are die-offs?
If you have recently been in a plague-infected area and have a fever or other signs or symptoms of plague within eight days, seek medical attention immediately.
What is a ground squirrel? What kinds of ground squirrel are currently affected?
A ground squirrel is a squirrel that lives in burrows underground. A tree squirrel lives in and builds nests in trees. Tree squirrels have not been identified with plague at this time. Some people call ground squirrels “whistle pigs,” but the term “whistle pig” is also used for other rodents such as marmots. The scientific name of the affected species is Urocitellus mollis. It is also known as the Piute ground squirrel.
What areas of Idaho are affected?
At this time, plague has been detected only in ground squirrels (NOT TREE SQUIRRELS) in central and southern areas of Ada County. For a map of the suspected area where plague may be present in wildlife, click here.
How do we know plague is present in the ground squirrels?
The Idaho Department of Fish and Game collected dead ground squirrels from several areas in Ada County and submitted them to public health laboratories for testing. The laboratory found the plague bacterium. Ground squirrel populations with plague can experience high mortality, sometimes evidenced by large numbers of carcasses.
Are you going to test more dead animals?
We do not need to test any more dead ground squirrels in the known die-off area for plague. Selective testing of a small number of dead ground squirrels in other areas may be done to determine the geographic range of the disease. Fill out a form at https://fishandgame.idaho.gov/content/plague to report animal die-offs or Contact your Idaho Department of Fish and Game office http://fishandgame.idaho.gov/public/about/offices/ (Southwest Regional Office,  465-8465).This will help determine the extent of the problem in the wildlife and help human health professionals target outreach and awareness efforts in appropriate areas.
How can I protect myself from plague?
- You and your pets should keep away from dead ground squirrels and their burrows because plague-carrying fleas might be present.
- Do NOT handle dead animals if you don’t have to.
- In public places, leave dead ground squirrels alone.
- If you have ground squirrels on your property, see disposal instructions below.
- If you enter an area posted for plague:
- Wear long-sleeved shirts and long pants.
- Use DEET on clothing in accordance with label instructions or wear clothing pre-treated with permethrin
- Use DEET on exposed skin, in accordance with label instructions.
What do I do if there are dead ground squirrels near my home?
Contact the Idaho Department of Fish and Game only (see contact information above) if there are several dead ground squirrels. This will help IDFG track the distribution of animal deaths. IDFG will let you know if they would like to collect the dead animals or if you should dispose of them.
How do I safely dispose of dead ground squirrels or other rodents or rabbits?
- Dispose of dead animals before pets have a chance to come into contact them.
- Use insect repellent to deter fleas, following label instructions.
- Wear long-sleeved shirts and long pants and apply DEET to your clothing or wear clothing pre-treated with permethrin.
- Apply DEET to your exposed skin.
- Put on disposable gloves (latex or rubber, for example)
- Spray the dead animal with a home insecticide that is labelled as effective in killing fleas. DO NOT spray live animals.
- Use a shovel to put the dead animal in a plastic garbage bag OR use a plastic bag with your gloved hand to pick up the dead animal, inverting the bag over the animal (like picking up dog poop).
- Close the bag and knot it tightly
- Put the bag with the dead animal into a second bag, close it, knot it tightly, and put it in the trash
- Put your gloves in the trash
What should I do about ground squirrel burrows near my home?
Plague easily kills ground squirrels. If ground squirrels near your home are alive, do not bother them and do not treat their burrows for fleas. If you notice several dead ground squirrels near your home, you can consider contacting a licensed pesticide applicator for assistance with flea control at burrows.