Zoonotic Diseases & Rodents

A zoonotic disease is a disease that can be passed from animals to humans. These diseases can be caused by viruses, bacteria, parasites, and fungi. Humans can contract zoonotic or vector-borne diseases through contact with an animal, its bodily fluids, its infected waste or its living environment, or through vectors—such from infected animals to humans via mosquitoes, fleas or ticks. 

While the diseases mentioned below generally affect wild rodents, such as rats or mice, regular veterinary care is important for the health of pet rodents. Because pet rodents such as mice, rats, guinea pigs, and hamsters can become sick, an annual veterinary exam is recommended.

Following are some zoonoses related to wild rodents:

Hantavirus

Hantavirus cases are rare in this country, but, since 1993, there have been 18 cases in Oregon. The state’s first case, reported in 1994, was a northwestern Oregon man who died from the disease.

According to the CDC, hantavirus pulmonary syndrome is a rare but serious respiratory infection that can be life threatening. Humans can become infected by inhaling dust contaminated by droppings, urine or saliva from infected rodents. Hantavirus can also be transmitted through bites from infected rodents or from direct contact with rodent excretions, followed by touching the mouth or nose prior to hand washing. It takes approximately two weeks for symptoms to appear, but can range from a few days to six weeks. Symptoms can be similar to some types of pneumonia or common respiratory viruses like influenza, and may include fever, headache, muscle aches, nausea and vomiting.

The deer mouse is the most common rodent carrier of hantavirus. Rodents that carry hantavirus are generally found in rural and sometimes suburban areas. The common house mouse does not spread the virus. The deer mouse is tan or brown in color with white hair on the underbelly, while the typical house mouse is gray.

Since 1994, over 850 cases of hantavirus have been reported in the US. Cases often occur in the spring after spring-cleaning in homes and businesses. Hantavirus is not spread from person-to-person, nor is it spread among domesticated animals, nor from domesticated animals to humans.

To minimize the risk of hantavirus you should:

• Avoid contact with wild rodents.
• Keep rodents away from buildings by keeping lawns mowed and homes free of debris and trash. Wood piles should be at least 12 inches off the ground.
• Make sure rodents don’t have access to food, water or nesting sites.
• Keep food scraps and garbage in rodent-proof metal or thick plastic containers with tight-fitting lids. Do not allow pet or animal food to sit out.
• Keep rodents out of buildings by using steel screens, caulk or weather stripping to seal holes or gaps around the house and garage doors. If openings near pipes and electrical wiring are present, seal with steel wool.
• If rodents are present, use snap traps with peanut butter mixed with oats as effective bait.
• Air out rodent infested places at least 30 minutes before clean-up.

Consider the following preventive steps before cleaning out possible rodent-infested areas:

• Do not sweep, brush or vacuum which will stir up dust.
• Protect yourself by wearing a particulate respirator face mask and use rubber, latex, vinyl, or nitrile disposable gloves.
• Spray the droppings or nests with a bleach solution or household disinfectant. (Mix 1.5 cups of household bleach in 1 gallon of water.) Leave solution on area for about 10 minutes. Once everything is wet, wipe up the debris with a damp paper towel, and then mop the area with the bleach solution.
• Thoroughly wash your hands with soap and water (or waterless alcohol-based hand cleaners when soap and water is not available).
• Seal all refuse in double plastic bags, and dispose of this, and personal protection equipment, in an appropriate waste disposal system.

Plague

While rare, there have been cases of plague in humans in Oregon. A cat in Crook County tested positive in 2011. And, in 2012, a Crook County man contracted the plague from a stray cat or mouse (that the cat had in its mouth). Plague can be passed from fleas feeding on infected wild mammals to pets such as cats and to their human owners. People can protect themselves, their family members and their pets by using flea treatments on your pets to prevent them from bringing fleas into your home.

Symptoms of plague typically develop within one to four days after exposure and include fever, chills, headache, weakness and a bloody or watery cough due to infection. Three clinical syndromes have been described: bubonic (lymph node infection), septicemic (blood infection), and pneumonic (lung infection). Bubonic plague is the most common form and is characterized by high temperatures, lethargy and swollen lymph nodes, most commonly in the neck and under the jaw. Infected lymph nodes may spontaneously abscess and drain.

People should contact their health care provider if plague is suspected and a veterinarian if pets or other animals exhibit symptoms consistent with the plague. Early treatment for pets and people with appropriate antibiotics is essential to curing plague infections. Untreated plague can be fatal for animals and people. Antibiotics to prevent or treat plague should be used only under the direction of a health care provider.

Health authorities offer the following recommendations to prevent plague:

• Avoid sick or dead rodents, rabbits and squirrels, and their nests and burrows.
• Keep your pets from roaming and hunting.
• Talk to your veterinarian about using an appropriate flea control product on your pets.
• Clean up areas near the house where rodents could live, such as woodpiles, brush piles, junk and abandoned vehicles.
• Sick pets should be examined promptly by a veterinarian.
• See your doctor about any unexplained illness involving a sudden and severe fever.
• Put hay, wood, and compost piles as far as possible from your home.
• Don’t leave your pet’s food and water where mice can get to it.
• Veterinarians and their staff are at higher risk and should take precautions when seeing suspect animal plague cases.

Prevention

• While the diseases mentioned above generally affect wild rodents, such as rats or mice, regular veterinary care is important for the health of every animal. Because pet rodents such as mice, rats, guinea pigs, and hamsters can become sick, an annual veterinary exam is recommended.
• One of the best ways to prevent zoonotic diseases is to promptly clean up pet waste. Many parasites or bacteria are not infectious in fresh pet waste, but become infectious over time if allowed to sit. Wash your hands thoroughly with hot, soapy water after playing with your pet rodent or handling its waste.
• If you have any questions about these diseases or concerns about your rodent's health, please consult your veterinarian. If you have concerns about your health, please seek medical attention from your health care provider.